Heavy Duty Oil Flooded Twin Screw Rotary ... - Ariel Corporation

ARIEL 

Heavy Duty 

Oil Flooded Twin Screw 

Rotary Compressors 

TECHNICAL MANUAL 

For Models: 

AR166, AR208, AR260K & AR260 

ARIEL CORPORATION 

35 BLACKJACK ROAD, MOUNT VERNON, OHIO 43050 

TELEPHONE: 740-397-0311 FAX: 740-397-3856 

(For additional contact information, see PAGE 7 - 10) 

VISIT OUR WEB SITE: www.arielcorp.com 

REV: 3/02

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 

! 

CAUTION 

GAS COMPRESSOR UNITS ARE COMPLICATED AND DANGEROUS 

PIECES OF EQUIPMENT. THOROUGH TRAINING AND 

FAMILIARIZATION WITH THE EQUIPMENT IS REQUIRED. 

BEFORE STARTING THIS UNIT: 

FAMILIARIZE YOURSELF WITH THE UNIT. 

READ AND STUDY START-UP AND SHUT-DOWN INFORMATION FOR 

BOTH PACKAGE AND COMPRESSOR CAREFULLY! 

A GAS/AIR MIXTURE UNDER PRESSURE CAN EXPLODE! YOU CAN 

BE SEVERELY INJURED OR KILLED. MAKE SURE THE 

COMPRESSOR IS SUFFICIENTLY PURGED OF ANY EXPLOSIVE 

MIXTURE BEFORE LOADING. 

AFTER COMPLETING THE ABOVE, BEGIN PROPER STARTING 

PROCEDURE. 

CAUTION 

DO NOT ATTEMPT TO START-UP UNIT WITHOUT REFER- 

RING TO THIS MANUAL SECTION 3: START-UP. IT IS ALSO 

ESSENTIAL TO REFER TO THE PACKAGER’S OPERATING 

MANUAL. 

! 

! 

CAUTION 

THIS MANUAL EDITION IS BASED ON THE CURRENT 

DESIGN, BUILD AND PRACTICES. THIS MANUAL MAY NOT 

BE APPLICABLE TO EQUIPMENT BUILT PRIOR TO THE 

DATE ON FRONT COVER AND IS SUBJECT TO CHANGE 

WITHOUT NOTICE. CONTACT ARIEL WITH ANY QUESTIONS, 

SEE PAGE 7 - 10. 

3/02

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 TABLE OF CONTENTS 

TABLE OF CONTENTS 

Design Specifications & Data .............................................................. 1-1 

General ................................................................................................................... 1-1 

Operating Theory .................................................................................................... 1-3 

Specifications ......................................................................................................... 1-5 

................................................................................................................................ 1-5 

Product Information and Safety Plates ................................................................... 1-8 

Important Safety Information ............................................................................. 1-9 

Fastener Tightening Torque ................................................................................. 1-10 

Tightening Torque Procedures ........................................................................ 1-11 

Ariel Bolting .......................................................................................................... 1-12 

Alarm & Shutdown (also see Section 4) ............................................................... 1-13 

Gas Discharge High Temperature Settings .................................................... 1-13 

Storage and Transportation of Compressor ......................................................... 1-13 

Installation ............................................................................................. 2-1 

General ................................................................................................................... 2-1 

Procedure For Setting and Aligning ........................................................................ 2-1 

Setting ............................................................................................................... 2-1 

Alignment .......................................................................................................... 2-1 

Vents and Drains .................................................................................................... 2-2 

Inlet Gas Debris Screens ........................................................................................ 2-3 

Inlet Gas Liquids ..................................................................................................... 2-3 

Start Up .................................................................................................. 3-1 

General ................................................................................................................... 3-1 

Start Up Check List ................................................................................................. 3-2 

Maximum Allowable Working Pressure .................................................................. 3-7 

Relief Valve Settings .............................................................................................. 3-7 

Filling and Priming an Oil Lube Oil System - Before Starting ................................. 3-7 

Filling The System ............................................................................................. 3-7 

Slide Valve Positioning - Hydraulic ......................................................................... 3-8 

Theory of Operation .......................................................................................... 3-8 

Visual Position Indicator (Yellow Pointer), Internally Changeable Models ........ 3-9 

Visual Position Indicator (Yellow Pointer), Externally Changeable Models ....... 3-9 

Slide Valve Positioning at Start-up .................................................................. 3-10 

Slide Valve Positioning - Hand Wheel .................................................................. 3-10 

Theory of Operation ........................................................................................ 3-11 

Slide Valve Positioning at Start-up .................................................................. 3-12 

Balance Oil Connection ................................................................................... 3-12 

Built In Volume Ratio Changes - Internally Changeable Vi .................................. 3-13 

Built In Volume Ratio Changes - Externally Changeable Vi ................................. 3-14 

Thrust Balance System ........................................................................................ 3-14 

Thrust Balance Pressure Adjustment .............................................................. 3-14 

3/02 i


Gas/Oil Separator Coalescing Filter - Scavenged Oil Line Flow Adjustment .......3-15 

Sour Gas Service with over 100 ppm to 2% H2S or Other Dangerous Gases .....3-15 

Compressor Re-Application ..................................................................................3-16 

Oil System, Lubrication & Venting ...................................................... 4-1 

General ...................................................................................................................4-1 

Lubricants ...............................................................................................................4-2 

Petroleum Based Oils - also referred to as mineral oils: ...................................4-5 

Synthetic Lubricants ..........................................................................................4-5 

Auxiliary Equipment ................................................................................................4-6 

Lube Oil Strainer ................................................................................................4-6 

Oil Cooler ...........................................................................................................4-6 

Temperature Control Valve ...............................................................................4-6 

Cold Ambient Temperatures ..............................................................................4-6 

Prelube Pump ....................................................................................................4-7 

Oil Pressure Regulating Valves .........................................................................4-7 

Oil Filters ...........................................................................................................4-7 

Liquids and Contaminants in Gas ......................................................................4-8 

Compressor Oil Pump .............................................................................................4-8 

Compressor Oil Supply Pressure Calculations .......................................................4-9 

Gas Balance Line Pressure (GBLP) Calculation ..................................................4-10 

Compressor Re-Application ..................................................................................4-10 

Warranty ...............................................................................................................4-10 

Lube Oil Shutdowns ..............................................................................................4-10 

Pressure: .........................................................................................................4-11 

Temperature: ...................................................................................................4-12 

Rotor Injection Flow ..............................................................................................4-12 

Flushing Requirements .........................................................................................4-12 

Maintenance .......................................................................................... 5-1 

General Introduction ...............................................................................................5-1 

Mechanical Seal ......................................................................................................5-2 

Replacing the Mechanical Seal .........................................................................5-3 

Optional Collared Retaining Bolts ......................................................................5-4 

Slide Valve Replacement - Internally Changeable Vi .............................................5-6 

Compressors with Individual Cover Plates ........................................................5-7 

Replacement .....................................................................................................5-7 

Slide Valve Cylinder Reassembly Into Compressor ..........................................5-7 

Slide Valve Axial Position Indicator Transducer .....................................................5-8 

Externally Changeable Slide Valve .......................................................................5-10 

Slide Valve Volume Ratio (Vi) Change - Externally Changeable Vi ................5-10 

Vi Spacer Adjustments - Externally Changeable Vi .............................................5-12 

Slide Valve Inspection/Replacement - Externally Changeable Vi .........................5-12 

Removal ..........................................................................................................5-12 

Replacement ...................................................................................................5-13 

Slide Valve Cylinder Assembly Into Compressor ............................................5-13 

Oil Pump and Geared Tooth Coupling ..................................................................5-14 

ii 3/02


Oil Pump Replacement ................................................................................... 5-14 

Coupling Replacement .................................................................................... 5-15 

Ethylene Glycol Contamination ............................................................................ 5-16 

Mineral Deposit Build-Up in Low Pressure Natural Gas Applications .................. 5-16 

Technical Assistance ........................................................................... 6-1 

Recommended Maintenance Intervals ................................................................... 6-1 

Daily .................................................................................................................. 6-1 

Monthly (in addition to Daily Requirements) ..................................................... 6-2 

Every 6 Months or 4,000 Hours (plus Daily/Monthly) ........................................ 6-2 

Yearly or every 8,000 Hours (plus Daily/Monthly/6 Months) ............................. 6-2 

Trouble Shooting .................................................................................................... 6-2 

Appendices ............................................................................................ 7-1 

Ariel Tools ............................................................................................................... 7-1 

Ariel Furnished Tools ........................................................................................ 7-1 

Minimum Hand Tools Required .............................................................................. 7-3 

Terms, Abbreviations and Conversion to SI Metric ................................................ 7-4 

Area ................................................................................................................... 7-4 

Flow - Gas ......................................................................................................... 7-4 

Flow - Liquid ...................................................................................................... 7-4 

Force ................................................................................................................. 7-4 

Heat ................................................................................................................... 7-4 

Length ............................................................................................................... 7-4 

Mass .................................................................................................................. 7-4 

Moment or Torque ............................................................................................. 7-5 

Power ................................................................................................................ 7-5 

Pressure or Stress ............................................................................................ 7-5 

Speed ................................................................................................................ 7-5 

Temperature ...................................................................................................... 7-5 

Time .................................................................................................................. 7-5 

Viscosity ............................................................................................................ 7-6 

Volume .............................................................................................................. 7-6 

Other Abbreviations .......................................................................................... 7-6 

Gas Analysis Common Abbreviations .................................................................... 7-8 

Metric Factors ......................................................................................................... 7-9 

Technical and Service Schools on Ariel Compressors ........................................... 7-9 

Ariel Customer Technical Bulletins (Formerly Ariel Newsletters) ........................... 7-9 

Vendor Literature .................................................................................................... 7-9 

Ariel Contact Information ...................................................................................... 7-10 

3/02 iii


NOTES 

iv 3/02


SECTION 1 - DESIGN SPECIFICATIONS & DATA 

General 

Ariel compressors are designed for ease of operation and maintenance. Experience has 

shown that an Ariel compressor will normally provide years of satisfactory performance with 

minimal proper maintenance. 

While Ariel rotary compressors share many similarities, each model has aspects that are 

unique to the particular model type. If you, as an operator, are familiar with Ariel reciprocating 

compressors, it is still important to review this rotary manual to determine the differences. 

If you are new to Ariel rotary compressors, it is critical that you become very familiar 

with this manual prior to operating the compressor. Rotary compressors are precision rotating 

equipment, requiring knowledgeable operation and maintenance. 

FIGURE 1-1: SIDE VIEW - ARIEL ROTARY COMPRESSOR WITH INTEGRAL OIL PUMP - TYPICAL 

Ariel rotary compressors feature positive displacement, single stage operation using oilflooded 

twin screw rotors. The compressors are designed primarily for natural gas but have 

applications for other gases, such as propane. Heavy duty babbitted journal bearings, antifriction 

rolling element thrust bearings, and a variable capacity, field changeable volume 

ratio (V i) allow rotary compressors to operate in a wide variety of gas applications. Internally 

or externally changeable volume ratio (V i ) slide valves are available. 

�� Г �� Г �� 

�� 

�� Г �� Г 

�� 

Vs Vi = 

----- 

Vd �� Г �� ) 

3/02 PAGE 1 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 1 - DESIGN SPECIFICATIONS & DATA 

Rotary compressors have few moving parts, can run at high speeds, can accommodate a 

wide range of compression ratios and operate with minimum pressure pulsations. They are 

generally applied in low suction pressure applications, discharging into medium pressure 

lines. To maintain high compression efficiency, care should be taken to operate the compressors 

as close to the installed slide valve volume ratio (V i) as possible. 

Flute 

Female 

(Driven) 

Rotor 

Male 

(Drive) 

Rotor 

FIGURE 1-2: MALE/FEMALE ROTOR PAIR (5/7 LOBE/FLUTE RATIO) 

Oil is the lifeblood of rotary screw compressors. Catastrophic damage can occur to rotors, 

bearings and mechanical seal without adequate oil quality, volume and viscosity. Oil selection 

is based on process gas composition, operating temperatures and pressures. If gas 

composition or operating conditions change, lubrication selection, gas/oil separator operating 

temperature and counter thrust balance pressure must be re-evaluated. 

During compressor operation, process gas will dilute the oil, reducing viscosity. Liquid and 

solid contaminants in the suction gas stream must be effectively removed to minimize the 

detrimental affects on the compressor and its oil system. Pressurized oil viscosity should 

never be allowed to drop below the minimum requirement. Ariel rotary screw compressors 

are designed for oil flooding of the compression chamber, with oil separation and recirculation, 

at minimal oil loss. Packager design and oil selection determines the amount of oil carryover 

(loss) downstream of the gas/oil separator. 

This manual is designed to provide information on installation, start up, operation, maintenance 

and trouble shooting of an AR166, AR208, AR260 or AR260K compressor. If you 

have any questions please contact your packager. If they are unable to provide resolution, 

they will refer your questions to Ariel Corporation. If you prefer, you may always contact Ariel 

directly (refer to “Ariel Contact Information” on page 7-10). 

This manual provides design specifications for standard current production equipment at 

publication date. Do not exceed information plates ratings for a particular compressor. 

PAGE 1 - 2 3/02 

Lobe


The data shown on the Information Plates is very important when communicating questions 

concerning an Ariel compressor. (Refer to Figure 1-3: on page 1-3) 

NOTE: USE SERIAL NUMBERS IN ALL CORRESPONDENCE. 

NOTE: THE CURRENT DESIGN OF THE ARIEL ROTARY COMPRESSORS FEATURES 

AN INTEGRAL OIL PUMP, MULTIPLE END COVERS, ANSI FLANGES AND 

INCH NPT EXTERNAL CONNECTIONS. 

NOTE: INTERNALLY CHANGEABLE Vi MODELS REQUIRE CHANGE OUT OF THE 

SLIDE VALVE TO CHANGE THE Vi OF THE UNIT. EXTERNALLY CHANGEABLE 

Vi MODELS REQUIRE CHANGE OUT OF A SPACER ONLY. 

NOTE: THE ROTARY COMPRESSORS OFFER TWO OPTIONS FOR LOADING AND 

UNLOADING: HYDRAULIC AND HANDWHEEL. 

The various rotary compressor configurations are shown in Figure 1-4:, Figure 1-5: and Figure 

1-6:. 

Operating Theory 

Information 

Plate 

Multiple End Covers - ‘N’ Version 

FIGURE 1-3: AUXILIARY END VIEW SHOWING TYPICAL INFORMATION PLATE LOCATION 

The rotary compressor’s oil-flooded, twin screw design consists of a male rotor which 

directly drives the female rotor. The male rotor lobes drive the female rotor flutes, as in a 

“spiral gear” motion. The male rotor is driven by a prime mover (engine or motor), which can 

be a direct drive or thru a speed increasing gear set. The female rotor is driven at a lesser 

speed; 5/7 times male rotor speed. Rotor tip speeds are generally between 49 to 164 feet/ 

second (15 to 50 m/s). 

The rotor length, diameter, lobe/flute and speed design determines compressor full load 

capacity. The selected slide valve determines internal compression ratio. Slide valve axial 

positioning control provides variable partial load capacities. Several slide valve/volume ratio 

(V i ) choices are available for each compressor model. Depending upon the option chosen, 

the volume ratio (V i) is field internally-changeable by changing the slide valve or field externally-changeable 

using spacers provided with the unit. 

3/02 PAGE 1 - 3


The internally changeable method requires changeout of the slide valve (refer to Figure 1-5: 

on page 1-6) and the externally changeable method requires changeout of a spacer only 

(refer to Figure 1-4: on page 1-6 and Figure 1-6: on page 1-7). 

As the compressor’s twin rotors un-mesh, at the top, the flutes and lobe voids are exposed 

to the suction gas stream and fill with gas. As the rotors turn out, the flutes and lobe voids 

are closed and sealed by the rotor housing, creating spiral segmental compression chambers 

which move gas axially toward discharge. Oil is injected into the compression chambers 

after they close off from the suction pressure, to provide sealing, cooling and 

lubrication. Rotor meshing, at the bottom, progressively reduces compression chambers volumes 

axially, to compress the gas/oil mixture. Rotor rotation exposes the compression 

chambers to the (radial/axial) discharge port, moving the compressed gas/oil mixture out of 

the compressor. 

Discharge piping carries the compressed gas/oil mixture to a coalescing filter-separator 

where the oil is separated from the process gas. The oil is piped to a cooler and re-circulated 

to the compressor. Refer to Figure 4-1: on page 4-3 or Figure 4-2: on page 4-4. 

PAGE 1 - 4 3/02


Specifications 

TABLE 1-1: BASIC SPECIFICATIONS 

MODEL AR166 AR208 AR260K AR260 

Male Rotor Diameter, in. (mm) 6.54 (166) 8.19 (208) 10.24 (260) 

Number of Male Rotor Lobes 5 

Number of Female Rotor Flutes 7 

L/D Ratio 1.6 1.2 1.6 

Operating Speed, RPM 1148 To 5739 918 To 4591 735 To 3673 

Inlet Volume, CFM (m 3 /h) To 600 (1019) To 950 (1614) To 1080 

(1835) 

To 1450 

(2464) 

Horsepower (kW) To 530 (394) To 820 (612) To 950 (708) To 1270 (947) 

Suction Pressure, psig (barg) To 115 (7.93) 

Discharge Pressure, psig (barg) To 362 (25.00) 

Maximum Discharge Temperature 248°F (120°C) 

Height - Mounting Feet to Rotors 6, in. (mm) 8.661 (220) 10.827 (275) 13.386 (340) 

Maximum Width, in. (m) 19.7 (0.5) 23.6 (0.6) 28.3 (0.72) 

Maximum Length, in. (m) 41.9 (1.1) 50.1 (1.3) 55 (1.4) 59 (1.5) 

Approximate Weight without Oil Pump, lb. (kg) 1050 (470) 1800 (820) 3100 (1400) 3300 (1500) 

Slide Valve Options a - Volume Ratio, Vi 2.0, 2.2, 2.6, 3.5, 4.8 

Oil Filter - Bearing, Seal & Control Cylinder, nominal 3 - 7 micron @ 98.7% Efficiency 

Oil Filter - Rotor Injection, nominal 15 - 16 micron @ 98.7% Efficiency 

Recommended Oil Retention in Gas/Oil Separatorb 2 minutes 

a. 2.0 Vi minimum, internally changeable slide valve only; 2.2 Vi minimum, externally changeable slide valve only. 

b. Recommended time depends on separator design. 

3/02 PAGE 1 - 5


Slide Valve 

Position Indicator 

FIGURE 1-4: TYPICAL SIDE VIEW CROSS-SECTION ANSI (HYDRAULICALLY CONTROLLED, EXTER- 

NALLY CHANGEABLE [SPACER] V i ) 

Slide Valve 

Position Indicator 

Hydraulic 

Control Piston 

Hydraulic 

Control Piston 

Vi Spacer 

Suction 

Internal 

By Pass 

Suction 

Internal By Pass 

Slide 

Valve 

Slide Valve 

Discharge 

FIGURE 1-5: TYPICAL SIDE VIEW CROSS-SECTION ANSI (HYDRAULICALLY CONTROLLED, INTER- 

NALLY CHANGEABLE [SLIDE VALVE] V i) 

PAGE 1 - 6 3/02 

Rotor 

Discharge 

Mechanical 

Seal 

Rotor 

Mechanical 

Seal


FIGURE 1-6: TYPICAL SIDE VIEW CROSS-SECTION ANSI (HAND WHEEL CONTROLLED, EXTERNALLY 

CHANGEABLE [SPACER] V i ) 

Table 1-2: HAND WHEEL TURNS VS. SLIDE VALVE TRAVEL (20 a TO 100% AXIAL POSITION) 

SLIDE 

VALVE b 

V i 

Hand Wheel 

V i Spacer 

NO. OF 

TURNS 

Rotor 

AR166 AR208 AR260K AR260 

TRAVEL 

IN. (cm) 

Internal Bypass 

NO. OF 

TURNS 

Suction 

Slide Valve 

TRAVEL 

IN. (cm) 

NO. OF 

TURNS 

a. 20% position is against stop. 

b. This table applies for externally changeable slide valves only. 

Discharge 

TRAVEL 

IN. (cm) 

Mechanical 

Seal 

NO. OF 

TURNS 

TRAVEL 

IN. (cm) 

4.8 25 2.5 (6.4) 34 3.4 (8.6) 44 4.4 (11.2) 39 3.9 (9.9) 

3.5 33 3.3 (8.4) 44 4.4 (11.2) 53 5.3 (13.5) 52 5.2 (13.2) 

2.6 43 4.3 (11.0) 56 5.2 (13.2) 65 6.5 (16.5) 68 6.8 (17.3) 

2.2 50 5.0 (12.7) 66 5.3 (13.5) 74 7.4 (18.8) 78 7.8 (19.8) 

3/02 PAGE 1 - 7


Product Information and Safety Plates 

Unit Information plate: Ariel Corporation 

address, Model number, Serial number, 

Maximum Rated Speed, Maximum Suction 

Pressure, Maximum Discharge Pressure, 

original furnished Oil Pump Model 

and Ariel shipping date. Safety Information. 

Inspectors tag. 

AUXILARY END VIEW 

SIDE VIEW 

Use suction flange tapped 

holes to install two (2) eyebolts 

(furnished in tool box) 

for lifting compressor separately 

Center of Gravity 

(Compressor Only) 

Compressor Serial Number, 

MAWP, Hydrostatic Test 

Pressure, Test Date, Model 

Number and Tester’s Personal 

Stamp are stamped on 

rotor housing 

Volume Ratio (Vi ) Plate 

Currently Installed Slide 

Valve - Change/Date 

Engine/Motor 

Direction of Rotation 

arrow, located at the 

drive end 

TOP VEIW 

DRIVE END VIEW 

FIGURE 1-7: PRODUCT INFORMATION AND SAFETY - TYPICAL ARIEL ROTARY COMPRESSOR WITH 

HAND WHEEL 

PAGE 1 - 8 3/02


Important Safety Information 

! 

CAUTION 

SEVERE PERSONAL INJURY AND PROPERTY DAMAGE 

CAN RESULT IF PRESSURE SYSTEM IS NOT 

COMPLETELY VENTED BEFORE LOOSENING THE BOLTS 

ON FLANGES OR FITTINGS TO PRESSURE CONTAINING 

AREAS. CONSULT ARIEL TECHNICAL MANUAL BEFORE 

PERFORMING ANY MAINTENANCE. 

! 

CAUTION 

NOISE GENERATED BY COMPRESSION MACHINERY 

CAN BE A SOURCE FOR HEARING INJURY. SEE 

PACKAGER’S INFORMATION FOR ANY SPECIFIC 

RECOMMENDATIONS. WEAR HEARING PROTECTION 

WHEN UNIT IS RUNNING. 

! 

CAUTION 

HOT GAS TEMPERATURES, ESPECIALLY THE GAS 

DISCHARGE AREAS, HOT OIL AND HIGH FRICTION 

AREAS CAN BE A SOURCE FOR BURNS. WEAR PROPER 

INSULATION WHEN WORKING AROUND THESE AREAS. 

SHUT DOWN UNIT AND ALLOW TO COOL BEFORE 

DOING MAINTENANCE IN THESE AREAS. 

CAUTION 

SURFACES MAY BE HOT AND CAN BE A SOURCE FOR 

BURNS. WEAR PROPER INSULATION WHEN WORKING 

AROUND THESE AREAS. 

3/02 PAGE 1 - 9


Fastener Tightening Torque 

Listed in the following tables are fastener tightening torque values, required for proper 

assembly of an Ariel AR166, AR208 AR260K or AR260 compressor. Refer to the section 

concerning a subject component for detailed assembly procedures. 

Threads are to be clean and free of burrs. 

Torque values are based on the use of petroleum type lubricants on both the threads and 

seating surfaces. Use lubricating oil or Lubriplate 630 on threads and seating surfaces, 

except where Loctite is specified. Molybdenum disulfide lubricants and Never-Seez are not 

to be used for fastener lubrication, unless specified, or excessive stresses can result with 

the listed values. 

TABLE 1-3: CAPSCREW (OR STUD-NUT) TIGHTENING TORQUE VALUES 

NOMINAL SIZE X 

THREAD PITCH 

CLASS 8.8 OR 12.9 CAP SCREW a 

(OR STUD-NUT) 

SEATING DOG POINT STUDS 

LB-FT (N·m) LB-FT (N·m) 

M6 x 1 5 (60 LB-IN) (7) 2 (24 LB-IN) (3) 

M8 x 1.25 13 (156 LB-IN) (18) 5 (60 LB-IN) (7) 

M10 x 1.5 25 (35) 11 (132 LB-IN) (15) 

M12 x1.75 45 (60) 19 (26) 

M16 x 2 115 (155) 48 (65) 

M20 x 2.5 225 (305) 93 (125) 

M24 x 3 385 (525) 160 (220) 

M27 x 3 570 (775) 240 (325) 

M30 x 3.5 775 (1050) 320 (435) 

M42 x 4.5 2170 (2950) 905 (1230) 

a. If applying this table to coupling retaining bolts, consult packager’s information for proper torque values, based 

on unit rating. Table values will provide bolting torque for maximum power transmission rating of compressor. 

TABLE 1-4: OTHER FASTENERS - TIGHTENING TORQUE VALUES 

APPLICATION 


THREAD PITCH 

LB-FT (N·m) 

Mechanical Seal Locknut M60 x 2 60 (81) 

M75 x 2 110 (149) 

M90 x 2 160 (217) 

M130 x 2 275 (373) 

Slide Valve - Nut M16 x 2 40 (54) 

M20 x 1.5 85 (115) 

Slide Valve Position Indicator - 

Mounting & Cover Screws 

M5 x 0.8 1 (12 LB-IN) (1.4) 

PAGE 1 - 10 3/02


TABLE 1-4: OTHER FASTENERS - TIGHTENING TORQUE VALUES 

APPLICATION 


THREAD PITCH 

Slide Valve Piston/Rod Nut M40 x 1.5 140 (190) 

M85 x 2 185 (251) 

Tightening Torque Procedures 

LB-FT (N·m) 

Listed below are some procedures which make fastener tightening more accurate and will 

help assure that the proper torque is being applied. 

1. Assure that the torque wrench is properly calibrated and used by qualified personnel 

to achieve the required fastener tightening torque for all critical parts. 

2. Always check to determine over what range the torque wrench is accurate, since 

most torque wrenches are not accurate over their entire range. 

3. Tighten critical multi-bolt assemblies in steps. Tighten each bolt until snug using a 

criss-cross pattern. Next, tighten each bolt to 25% of full torque, moving across from 

bolt to bolt, in a criss-cross pattern. Repeat this step for 50%, 75%, and 100% of full 

torque. 

4. Always apply a steady slow force to a torque wrench, do not jerk it. When a torque 

wrench is jerked the amount of torque applied can be as much as one and a half 

times the amount set on the wrench. For example, if a wrench is set at 80 lb x ft 

(108 N·m) but is jerked, 120 lb x ft (163 N·m) torque can be applied. 

5. Always do the final tightening with a torque wrench. Do not tighten the fastener with 

a ratchet or impact wrench and then "check" the torque with a torque wrench. 

6. Do not double tap a torque wrench. Rapidly double tapping a torque wrench will 

make the torque on the bolt more than what is set by a significant amount. If it is 

desired to check the setting release all pressure on the wrench and then slowly 

apply a steady force until the click is felt. 

7. Always reset the torque wrench to its lowest setting when the job is complete. If the 

torque wrench is left in a high setting the spring in it is stressed and will become 

inaccurate with time. If the torque wrench is put back to its lowest setting the spring 

will relax and retain its accuracy. 

8. Do not use a torque wrench to break fasteners loose as it may overload the torque 

wrench and/or cause loss of calibration. 

9. For applications requiring the use of a boxed end or crowsfoot type adapter with a 

torque wrench to reach not readily accessible fasteners, the torque wrench setting 

will not be the actual torque applied to the fastener. 1 

10. The ratio of actual torque at the fastener with that on the wrench scale is a function 

of the adapter's length and its position in relation to the torque wrench beam and 

the location on that at which the force is applied (see Figure 1-8:). 

L 

Tw = 

Ta⎛------------ 

⎞ 

⎝L + A⎠ 

1. The exception is when the adapter is 90° to the torque wrench. The torque will be the same as on the wrench 

scale (see Figure 1-9:). 

3/02 PAGE 1 - 11


Tw = Torque wrench setting, lb x ft or N·m 

Ta = Torque required at fastener, lb x ft or N·m 

L = Length of wrench, ft or m (from square drive end to center point of force on 

handle) 

A = Length of adapter, ft or m (measured through end of adapter on a line parallel 

to the center line of the wrench) 

These are general guidelines to assist in the proper use of torque wrenches. Consult with 

your torque wrench dealer for more detailed information. 

Ariel Bolting 

FORCE 

FIGURE 1-8: TORQUE WRENCH WITH ADAPTOR AT ANY ANGLE 

FORCE 

FIGURE 1-9: TORQUE WRENCH WITH ADAPTOR AT RIGHT ANGLE 

Bolts have been selected that meet Ariel's strength, elongation, sealing and locking requirements. 

Proper bolting must be used and tightened to the values listed in Table 1-3 and Figure 

1-4 on page 1-10. 

Figure 1-10: is provided to assist in the identification of bolts used in an Ariel compressor. 

PAGE 1 - 12 3/02


FIGURE 1-10: METRIC BOLT IDENTIFICATION - HEX SOCKET HEAD & 12 POINT, CLASS 8.8 OR 12.9 

Alarm & Shutdown (also see Section 4) 

Gas Discharge High Temperature Settings 

! 

A gas discharge high temperature shutdown is required. Set within 10% of normal operating 

temperature, to a maximum of 238°F (114°C) alarm and 248°F (120°C) shutdown. High temperature 

limits are based on rotating clearance requirements. 

NOTE: EXCEEDING THE HIGH TEMPERATURE SHUTDOWN LIMITATION WILL 

RESULT IN CATASTROPHIC EQUIPMENT FAILURE. 

Storage and Transportation of Compressor 

8.8 

CAUTION 

WHEN RE-ASSEMBLING OR REPLACING BOLTING, SEE 

THE PARTS LIST TO DETERMINE THE PROPER 

FASTENER GRADE AND PART NUMBER. ALL SPECIAL 

FASTENERS MUST BE REPLACED WITH ARIEL PARTS. 

Protect compressor to prevent corrosion and seal to prevent exchange of atmosphere, when 

inactive, in storage or when transporting. Consult Ariel for instructions to protect and seal 

compressor to ER-25-1. 

When transporting the packaged skid, remove the center section of the drive coupling. 

3/02 PAGE 1 - 13 

12.9


NOTES 

PAGE 1 - 14 3/02


SECTION 2 - INSTALLATION 

General 

Compressor installation with the associated driver and piping, is to be done with care and 

precision. This section does not attempt to address all of the concerns that can arise during 

installation, but addresses many of the primary considerations. 

Procedure For Setting and Aligning 

The following points deserve special attention during the setting and alignment of the compressor: 

1. Be sure that driver will rotate compressor rotor drive shaft in proper direction, 

prior to start-up. See Figure 1-7: on page 1-8, drive end view for rotation arrow. 

NOTE: THE COMPRESSOR DRIVE SHAFT ROTATES CLOCKWISE WHEN OBSERVER 

IS FACINIG THE COMPRESSOR DRIVE SHAFT END. ANY REVERSE ROTA- 

TION CAN RESULT IN SERIOUS DAMAGE TO THE COMPRESSOR. 

2. The skid design should: 

Transmit compressor and driver reaction forces to the foundation. 

Assure that there is a sufficient mismatch between the shaking forces and the 

natural frequency of the skid. 

Have sufficient stiffness and strength so that the compressor can be mounted 

flat with no bending or twisting of the compressor casing, and so that proper 

compressor coupling alignment can be attained and maintained. This can be 

accomplished by shims or careful grouting. 

Setting 

The following procedure is to be used for setting the compressor on the skid: 

After finding the approximate position of the compressor frame, the mounting bolts are to be 

tightened in place and then loosened. Shims are then to be adjusted so there is no movement 

more than a variation of 0.002 inches (0.05 mm) between the bottom of the feet and 

the skid supports. Consult Packager’s information for mounting bolt tightening torque values. 

This work must be performed prior to the addition of piping. 

Alignment 

Proper alignment is necessary for satisfactory performance. A flexible coupling will not make 

up for poor alignment. Misalignment can result in: 

3/02 PAGE 2 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 2 - INSTALLATION 

• High bending moment on the compressor drive shaft 

• Large axial forces which reduce thrust bearing life 

• Excessive wear to the bearings 

• And if severe, probable damage to various components 

An Ariel compressor may be aligned by any of a number of acceptable methods such as: 

Face/peripheral 

• 

Reverse indicator 

• 

Across the disc pack 

• 

• Optical 

• Laser 

• Mechanical direct to computer 

When aligning a unit some procedural concerns are: 

Soft foot (compressor and driver are not laying flat) 

• 

Repeatable readings 

• 

Which way indicator moves (plus or minus) 

• 

• Thermal growth 

• Piping stresses 

• Indicator sag 

When properly aligned the forces on the connected equipment will be at a minimum. This 

will result in long bearing life and a smooth running unit. Consult Packager’s information for 

alignment procedure. 

Vents and Drains 1 

It is critical, for the safe operation of the compressor, to assure that all vents and drains are 

open, functional and, if necessary, tubed off of the skid or out of the building. Depending 

upon your climate and insect population it can be necessary to install screens over the vents 

and drains to assure that they do not become blocked. This can be essential if the compressor 

is shutdown for a long period of time. 

Some other points are: 

1. A vent should be provided to safely relieve pressure from the system. 

2. Adequate vents and drains are to be provided for mechanical seal weepage and 

rotor housing oil drainage. All vents and drains must be installed in such a manner 

as to prevent the collection of liquids that could cause the build up of either 

gas or liquid. When a gas heavier than air is involved, vent and drain design 

must be accommodating. 

3. Do not block view of mechanical seal weepage tube, as oil leakage rate is a 

visual indication of seal condition. 

1. Also see Section 4. 

PAGE 2 - 2 3/02


Inlet Gas Debris Screens 

Foreign matter in the gas stream can effect compressor wear and lubrication. Inlet gas 

debris start-up screens with a maximum 75 micron (0.003 in.) openings are recommended 

to be installed upstream of the compressor suction flange. These screens should be monitored 

by differential pressure and cleaned or replaced before differential pressure 

approaches the collapse pressure of the screen. 

Inlet Gas Liquids 

Liquid water and gas condensates in the process gas stream have detrimental affects on oil 

system gas/oil separator operating temperature and oil viscosity. Liquid slugging that can 

adversely affect the compressors’s mechanical operation and oil system must be effectively 

removed or compressor damage will occur. 

NOTE: SOLID AND LIQUID CONTAMINANTS IN THE PROCESS GAS SYSTEM MUST 

BE EFFECTIVELY REMOVED UPSTREAM OF THE COMPRESSOR. 

NOTE: FREE LIQUIDS THAT ARE NOT REMOVED CAN BE PARTICULARLY TROU- 

BLESOME IN LOW PRESSURE NATURAL GAS SERVICE APPLICATIONS. 

MINERAL DEPOSITS (SALT AND CALCIUM) CAN BUILD UP ON THE SUCTION 

STRAINER SCREEN AND IN THE COMPRESSOR DUE TO DISSOLVED MINER- 

ALS IN WATER SATURATED PROCESS GAS. THESE MINERALS PLATE OUT 

WHEN WATER FLASHES OFF DUE TO PRESSURE DROP OR HEAT. 

3/02 PAGE 2 - 3


NOTES 

PAGE 2 - 4 3/02


SECTION 3 - START UP 

General 

To ensure a smooth start up, it is important that the items in the Start Up Check List, provided 

in this section, be positively satisfied. It is also important that the operator understand 

how to operate the compressor in a safe and efficient manner, prior to start up. 

! 

CAUTION 

BEFORE STARTING A NEW COMPRESSOR, OR AFTER RE- 

LOCATING OR RE-APPLYING A COMPRESSOR, OR AFTER 

MAJOR OVERHAUL, BE SURE TO COMPLETE AND CHECK 

OFF ALL THE ITEMS ON THE START UP CHECK LIST 

SHOWN IN THIS SECTION. THIS LIST IS DESIGNED TO HELP 

ASSURE SAFETY IN STARTING AND OPERATING THE COM- 

PRESSOR. 

! 

CAUTION 

FOR SAFE OPERATION, DO NOT ATTEMPT TO START-UP 

THE UNIT WITHOUT BEING COMPLETELY KNOWLEGABLE 

OF THE INFORMATION CONTAINED IN THIS SECTION. IT IS 

ALSO ESSENTIAL TO REFER TO THE PACKAGER’S OPER- 

ATING MANUAL. 

3/02 PAGE 3 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 3 - START UP 

Start Up Check List 

Compressor Model AR-__________ Serial No. R-___________ Slide Valve Vi ________ 

Slide Valve Control Activation: Hydraulic_____ Hand Wheel_____ 

Driver Manufacturer____________________Model _____________________________ 

Driver Rated Speed_____________________Speed Increasing Gear Ratio 

Packager____________________________Packager Unit No.____________________ 

Date Packager Shipped________________Serviceman_________________________ 

Customer____________________________Start Up Date________________________ 

Location____________________________Field Contact________________________ 

Field Telephone No.___________________Unit Location________________________ 

Gas Service_______________________________ 

Compressor Oil - Make/Grade______________________________________________ 

Check List - Prior To Starting YES NO 

1. Are the correct Ariel parts book, technical manual, special 

tools, Vi shims (externally changeable) and spares available? _____ _____ 

2. Have the design limitations for the compressor model such as 

MAWP, maximum suction & discharge pressures, maximum & 

minimum speed, discharge temperature been checked? _____ _____ 

3. Have the Packager’s design operating conditions been reviewed? 

Pressure, PSIG (kPa): Suction _________ Discharge_________ 

Temperature, °F (°C): Suction _________ Discharge_________ 

_____ _____ 

Maximum RPM__________ Minimum RPM___________ 

4. 

Current Gas Analysis Reviewed__________ SG__________ 

If start-up conditions are different, check with Packager or Ariel. 

Soft Foot Check [max. allowable 0.002” (0.05 mm)]: Have the compressor 

feet supports been shimmed so the machine is not twisted or bent? _____ _____ 

5. Have compressor anchor bolts been re-torqued? _____ _____ 

6. Have the piping and supports been checked to be sure they do 

not bend or stress compressor? _____ _____ 

7. Have coupling bolt torque values been rechecked? _____ _____ 

8. Has the compressor to driver alignment been checked? 

See compressor outline drawing for shaft thermal growth value. 

_____ _____ 

9. Record coupling dial indicator readings in inches (mm) at the 

3, 6, 9 & 12 o’clock positions on lines provided: 

Face Rim 

PAGE 3 - 2 3/02


Compressor Model AR-__________ Serial No. R-___________ Slide Valve V i ________ 


10. Does the compressor rotor turn freely? _____ ______ 

NOTE: ROTARY COMPRESSOR THRUST BEARING PRELOAD PRODUCES A NOR- 

MAL “ZERO” AXIAL THRUST. EXCESSIVE STUBSHAFT AXIAL FORCE, 

PUSHING OR PULLING, WILL RESULT IN BEARING DAMAGE. 

11. Has coupling center section been re-installed and has coupling been 

inspected for excessive axial distortion forces, pushing or pulling? _____ ______ 

12. Has preservation oil been drained from rotor housing? _____ ______ 

13. Have oil & gas systems been pressurized & leak tested? 

14. Has proper oil been installed that matches operating conditions 

_____ ______ 

with a viscosity adequate for current gas analysis? 

15. Has oil supplier provided gas dilution versus predicted oil 

_____ ______ 

viscosity information? 

16. Has the compressor oil system been filled with oil to the proper 

_____ ______ 

level without over filling? _____ ______ 

17. Is the compressor oil supply isolation valve open? _____ ______ 

NOTE: CLEARLY LABEL UNIT WITH COMPRESSOR OIL MAKE/GRADE CURRENTLY 

IN USE. 

18. Does the compressor oil system low level shutdown work? _____ ______ 

19. Have the properly rated gas inlet separator, oil filters and strainers, 

and separator coalescing elements been installed? _____ ______ 

20. Are the oil filter elements and all oil piping primed with oil? 

21. Is the low oil differential pressure shutdown installed and tubed 

_____ ______ 

correctly to the bearing oil supply and scavenger oil gallery? _____ ______ 

22. Is the low oil differential pressure shutdown set & does it work? 

23. Is there an oil cooler? Note: Recommended compressor inlet oil 

_____ ______ 

temperature is 150°F (66°C). _____ ______ 

24. Is the rotor injection oil temperature control valve setting appropriate for 

start-up conditions? _____ ______ 

25. Is the oil temperature control valve piped for a “mixing” condition? _____ 

26. If so equipped, is there a working vibration shutdown mounted on 

______ 

the compressor or drive train? 

27. Is there some method of suction pressure control upstream of the 

_____ ______ 

compressor? (Maximum suction pressure = 115 psig) 

28. Are the suction and discharge pressure shutdowns set and 

_____ ______ 

working? 

29. Are the safety relief valves installed and working to protect 

_____ ______ 

compressor gas and oil piping systems? _____ ______ 

3/02 PAGE 3 - 3




30. Is the gas high discharge temperature shutdown installed, set 

at 10% above anticipated temperature & working? _____ _____ 

31. Is the mechanical seal leakage tubing installed, unplugged 

and visible to determine if leakage occurs? _____ _____ 

32. Have the gas suction lines been blown out to remove 

water, slag, dirt, etc.? _____ _____ 

33. Has strainer screen been installed upstream of compressor 

suction? _____ _____ 

34. Were the compressor bearings and mechanical seal prelubed prior 

to starting? Note: A prelube pump is required. _____ _____ 

35. Does the driver rotation match the compressor rotation arrow? _____ _____ 

36. For engine driven units, has the machine been rolled to make 

sure it is free? _____ _____ 

37. For other drivers, has the machine been barred over by hand to 

ensure it is rolling free? _____ _____ 

38. For machines compressing a combustible gas, has the piping 

and compressor been purged to remove all air? _____ _____ 

39. Have start-up instructions for other package equipment been 

followed? _____ _____ 

40. Has compressor slide valve (internally changeable) been moved to 0% 

(unloaded) axial position, then hydraulic pressure released to verify 

spring will move slide valve to about 20% axial (part load) position? _____ _____ 

41. Has the compressor slide valve been moved back to zero percent or 

minimum load position, to allow compressor to start-up unloaded? _____ _____ 

42. Have bearing, mechanical seal and gas balance line operating 

pressures been determined for normal operation & shut-down 

settings? _____ ____ 

PSIG (bar g): Bearing & Seal Balance Line 

Operating 

Shut-Down N/A 

43. Has the Packager’s representative reviewed the Packager’s Start-Up 

and Operating Instructions for the unit with the unit operator? _____ _____ 

Check List - After Starting YES NO 

1. When idle speed is achieved, immediately load compressor to 25% 

minimum slide valve axial position & increase minimum driver speed 

if necessary to stabilize load. Did the compressor bearing oil pressure 

come up immediately after loading compressor? _____ _____ 

2. Are the oil filters, bearing, mechanical seal, rotor injection, separator 

and gas balance line pressure gauges working? _____ _____ 

PAGE 3 - 4 3/02



Check List - After Starting YES NO 

3. Are the oil filter differential pressures less than 30 psi (2.1 bar g), 

unless otherwise specified. ____ ____ 

4. Did the compressor develop discharge pressure when moving 

slide valve from unloaded to loaded position? ____ ____ 

5. Has the oil side of the slide valve control cylinder been purged of 

gas and slide valve moved to an appropriate load position? ____ ____ 

6. After the slide valve is in an appropriate load position, does it hold 

that position? ____ ____ 

7. Have compressor oil system regulating valves been adjusted 

for minimum required bearing and slide valve hydraulic pressures? ____ ____ 

8. Any strange noises or shaking in the compressor or piping? ____ ____ 

9. Is the compressor system oil level within acceptable limits? ____ ____ 

10. Are bearing and balance oil pressure above minimum 

pressure required for current operating condition? ____ ____ 

11. Is the high discharge temperature shutdown working? ____ ____ 

12. Is the high discharge gas temperature shutdown set at approx. 

10% above normal discharge temperature? 248°F (120°C) max. ____ ____ 

13. Is the mechanical seal weep hole leaking oil? Drops/minute. ____ ____ 

14. Are there any other oil leaks? If so, where? ____ ____ 

15. Are the scrubber dumps and high level shutdowns working? ____ ____ 

16. Are the scrubber dumps removing all liquids from the gas without 

obvious carryover? ____ ____ 

17. Are there sands, oxides or other solid contaminants in the gas? ____ ____ 

18. Is the overspeed shutdown set? ____ ____ 

19. Is the mechanical seal sealing oil and gas properly at the shaft? ____ ____ 

20. Has needle valve on separator filter scavenged oil line been 

adjusted to show primarily gas movement at flow indicator? ____ ____ 

21. Has counter thrust gas balancing pressure been adjusted for current 

operating conditions? ____ ____ 

22. Have all package safety functions been tested to ensure unit 

shutdown upon malfunction? ____ ____ 

23. After running compressor for 24 hours, are oil filter and separator 

differential pressures less than maximum allowable? ____ ____ 

24. Upon shutdown verify that compressor does not run in reverse 

rotation for more than 2 seconds to assure check valve operation? ____ ____ 

25. Has initial compressor operating data been recorded? ____ ____ 

26. Has Ariel’s “Compressor Warranty Notification and Installation 

List Data” form and a copy of this Start-up Check List and Log 

Sheet been completed and mailed to Ariel? ____ ____ 

3/02 PAGE 3 - 5


Company/Location Unit 


TABLE 3-1: TYPICAL LOG SHEET 

�� 

Operator 

Suction Pressure, psig (barg ) 

Suction Temperature, °F (°C) 

Discharge Pressure, psig (barg ) 

Discharge Temperature, °F (°C) 

Driver Speed, RPM 

Compressor Speed, RPM 

Slide Valve Axial Position (% or number 

of turns) 

Gas Flow Rate, MMSCFD (m 3 /s n ) 

Driver Load, HP (kW) 

Bearing Oil Pressure, psi (barg ) 

Bearing Oil Filter Differential, psi (bar g ) 

Compressor Bearing Oil Supply Temperature, 

°F (°C) 

Rotor Injection Oil Filter Differential, psi 

(barg ) 

System Oil Temperature, °F (°C) 

Gas Balance Pressure, psig (barg ) 

Separator Coalescing Filter 

Differential, psi (bar g ) 

Coalescing Scavenged Oil Line Valve 

Adjusted & Flow Observed 

Mechanical Seal Weep Rate, 

drops/minute 

System Oil Level 

Compressor Oil Added, gal. (L) 

Remarks: 

PAGE 3 - 6 3/02


Maximum Allowable Working Pressure 

All Ariel Rotary Compressors have a "Maximum Allowable Working Pressure (MAWP)." The 

MAWP, the hydrostatic test pressure, and the test date are stamped on every rotor housing, 

adjacent to the suction cover or on the suction end (see Figure 1-7: on page 1-8). 

API Standard 619, Third Edition, June 1997, Paragraph 3.1.18 defines "Maximum Allowable 

Working Pressure" as follows: 

"Maximum allowable working pressure (MAWP): The maximum continuous 

pressure for which the manufacturer has designed the equipment (or any part to 

which the term is referred), when handling the specified fluid at the maximum 

specified temperature." 

Relief Valve Settings 

It is the responsibility of the packager to provide relief valves to protect equipment, piping 

and oil separator in compliance with API Standard 619, paragraphs 5.4.3.6.1 and 5.4.3.6.3. 

Maximum relief valve settings are not to exceed the MAWP rating of the compressor or piping 

components whichever is less. 

Filling and Priming an Oil Lube Oil System - Before Starting 

Filling The System 

! 

CAUTION 

OPERATING CONDITIONS MUST NOT EXCEED COMPRES- 

SOR DESIGN LIMITATIONS. 

1. Fill the oil filters, piping and gas/oil separator to a level high on the sight glass. 

2. Run the prelube pump to assure system is filled, and bearings and seals are 

pre-lubed. Bleed piping and cooler high points vents to remove trapped air pockets. 

Check sight glass on separator. Oil level at start-up could be high or low on 

the site glass depending on component elevation. DO NOT OVERFILL. Proper 

oil system level is to be checked after compressor is operating when temperatures 

and pressures have stabilized and should be mid-point of the site glass, 

during normal operation. 

3/02 PAGE 3 - 7


Slide Valve Positioning - Hydraulic 

On compressors furnished with hydraulically positioned slide valves, valve position may be 

hydraulically changed, from 100% to minimum axial position with the compressor running or 

stopped, to adjust the compressor's capacity. Hydraulic pressure, at a pressure greater than 

discharge pressure, is used to move the slide valve in an unload direction. Spring tension 

and/or discharge pressure exert a force on the slide valve in the load direction. Individual 

compressor package design determines whether slide valve hydraulic oil is ported with manually 

operated valves or is integrated into the control system's automation using remote 

actuated valves. Refer to Figure 3-1: on page 3-9. 

Theory of Operation 

To unload, open the “in” shutoff valve (bottom connection) with the “out” shutoff valve closed 

(top connection). Compressor oil enters the hydraulic cylinder moving the slide valve toward 

the discharge end to unload. 

To hold, close both the “in” and “out” shutoff valves. Oil is captured in the cylinder and holds 

the slide valve in position. 

To load, open the “out” shutoff valve with the “in” shutoff valve closed. Discharge gas moves 

the slide valve toward the suction end, discharging oil into the rotor housing to load. 

PAGE 3 - 8 3/02


Axial 

Position 

Indicator 

Oil - Out 

Oil - In Control Piston 

at 25% 

100% Axial Position - 

Full Load 

100% 

(Full Load) 

FIGURE 3-1: SLIDE VALVE AXIAL POSITIONING - TYPICAL HYDRAULICALLY CONTROLLED INTERNALLY 

CHANGEABLE V i 

Visual Position Indicator (Yellow Pointer), Internally Changeable 

Models 

The yellow pointer provides visual indication of the slide valve's axial position from 0% to 

100%. The axial position is set to 0% for start-up, and is then adjusted for 25% to 100% for 

continuous operation. (Refer to Figure 3-1:). The pointer is shaft mounted with a set screw 

friction fit and can be adjusted for accuracy to match 0% or 25% and 100%. See "Slide Valve 

Axial Position Indicator Transducer" on page 5-8 for more details. 

Visual Position Indicator (Yellow Pointer), Externally Changeable 

Models 

The yellow pointer provides visual indication of the slide valve’s axial position from 20% to 

100%. A 20% position stop limits the travel to a 20% minimum position and the slide valve 

spring is not used. (Refer to Figure 5-9: on page 5-11 and Figure 5-10: on page 5-11 for 

Hand Wheel Controlled and Hydraulically Controlled versions, respectively). The axial posi- 

3/02 PAGE 3 - 9 

25% 

0% 

25% Axial Position - 

Min. Continuous Load 

Axial Position Indicator - Pointer 

Slide Valve 

at 25% 

0% (Unloaded) 

Yellow 

Pointer


tion is set to minimum (20%) for start-up and is then adjusted for 25% to 100% for continuous 

operation. The pointer is shaft mounted with a set screw friction fit and can be adjusted 

for accuracy to match 20% or 25% or 100%. See See “Slide Valve Axial Position Indicator 

Transducer” on page 5-8. for more details. 

NOTE: WHEN THE V i SPACER IS CHANGED, THE INDICATOR RANGE STICKER MUST 

ALSO BE CHANGED. 

Slide Valve Positioning at Start-up 

Prior to starting, operate the prelube oil pump to provide control cylinder hydraulic pressure 

and position hydraulic valve to move slide valve to the minimum (unloaded) position, see 

Figure 4-1: on page 4-3. Position the hydraulic valve to maintain slide valve in the minimum 

position during start-up. Position other oil system valves, as required, for normal operations. 

After starting, and as soon as idle speed is achieved, immediately load compressor to 25% 

minimum slide valve axial position which is done by removing oil from the cylinder. The slide 

valve's internal spring will position the internally changeable slide valve, or the fixed stop for 

externally changeable, to approximately the 20% axial position, then the developed discharge 

gas pressure will continue to move the slide valve toward the full load position. When 

the 25% position is achieved, position hydraulic valve to hold the slide valve at this position. 

Bearing oil pressure and discharge pressure should increase immediately after loading the 

compressor. 

NOTE: COLD OIL EXITING THE CONTROL CYLINDER WILL DRAMATICALLY 

INCREASE SLIDE VALVE POSITIONING TIME COMPARED TO HOT OIL. IT MAY 

BE NECESSARY TO HEAT TRACE AND INSULATE CONTROL CYLINDER OIL 

TUBING LINES FOR COLD WEATHER APPLICATIONS. 

After compressor is up to rated speed, the slide valve may be moved to an appropriate load 

position by operating the hydraulic valve to relieve hydraulic oil pressure in the cylinder. Discharge 

gas pressure will move the slide valve toward the full load position. See "Theory of 

Operation" on page 3-8 for more details regarding unload, hold & load. 

NOTE: ANY OIL LEAKAGE OUT OF THE SINGLE ACTING CONTROL CYLINDER OR 

ACROSS THE CONTROL PISTON SEALING RING WILL MOVE THE SLIDE 

VALVE TOWARD THE FULL LOAD POSITION. 

Slide Valve Positioning - Hand Wheel 

The slide valve position may be manually changed, from 100% to 20% axial position with the 

compressor running or stopped, to adjust the compressor's capacity. A manual hand wheel 

is used to move the slide valve in both load and unload directions, using a non-rising stem 

design. A stem locking device is used to hold the slide valve in a given position. The slide 

valve's axial position is determined by counting the number of hand wheel turns, as shown in 

Table 1-2 on page 1-7. Refer to Figure 3-2: on page 3-12. 

The slide valve cylinder piston's seal ring is designed for oil pressure containment. Filtered, 

pressured compressor oil is connected to the control cylinder, on the slide valve piston's 

PAGE 3 - 10 3/02


hand wheel side, as a balancing force during hand wheel operation. Discharge pressure 

always exerts a force on the slide valve in the load direction. Refer to Figure 4-2: on page 4- 

4 for the balance oil connection details. 

For ease of hand wheel operation the cylinder uses a balancing oil line, to allow for oil displacement 

and oppose discharge pressure forces on the slide valve. Oil fills the control cylinder 

as the slide valve moves toward the discharge end (unload position), and oil empties 

from the control cylinder as the slide valve moves toward the suction end (load position). Filtered 

oil also lubricates the piston's wear bands and sealing ring. 

This slide valve cylinder design may allow for the conversion between manual & hydraulic 

slide valve operation, with a minimum of conversion components. Contact Ariel for conversion 

details. 

Theory of Operation 

To unload the compressor, the slide valve can be adjusted when the compressor is pressurized 

and operating. To adjust capacity, loosen the stem locking device, so the stem is free to 

turn. Turn the stem by using the hand wheel on the outboard shaft end. When facing the 

hand wheel, turn the wheel counter-clockwise to unload, moving slide valve toward discharge 

end. 

To hold the slide valve position, re-tighten the stem locking device to the torque value shown 

in Table 1-4 on page 1-10. 

To load the compressor, the slide valve can be adjusted when the compressor is pressurized 

and operating. To adjust capacity, loosen the stem locking device, so the stem is free to turn. 

Turn the stem by using the hand wheel on the outboard shaft end. When facing the hand 

wheel, turn hand wheel clockwise to load, moving slide valve toward suction end. 

To hold the slide valve position, re-tighten the stem locking devise to the torque value shown 

in Table 1-4 on page 1-10. 

3/02 PAGE 3 - 11


Hand Wheel Balance Piston Balance Cylinder 

Slide Valve Positioning at Start-up 

Prior to starting, unload the compressor by moving the slide valve to a 20% axial position 

against the internal stop pin (refer to Figure 3-2:). After starting and when compressor is at 

rated speed, move the slide valve to a load position appropriate for the operating conditions. 

See "Theory of Operation" on page 3-11 for more details regarding unload, hold and load. 

Balance Oil Connection 

V i Spacer Slide Valve 20% Position Stop 

FIGURE 3-2: SLIDE VALVE AXIAL POSITIONING - TYPICAL HAND WHEEL CONTROLLED 

Beginning December, 2000, all AR model rotary compressors with the hand wheel option 

are shipped with the slide valve cylinder’s balance oil connections plugged. The Packager is 

responsible for installing this line to the rotor injection oil supply, downstream of appropriate 

filtration but upstream of the rotor injection oil flow check and regulating valves. Refer to Figure 

4-2: on page 4-4 for a detailed illustration of oil flow. 

Compressors with hand wheel capacity control can change the slide valve’s axial position by 

manually turning the hand wheel, in both the load and unload directions, between 100% (full 

load) and 25% (minimum continuous load). Discharge pressure always exerts a force on the 

slide valve, in the load direction, that is opposed by balance oil pressure. Filtered, pressurized 

compressor oil is connected to the slide valve control cylinder, on the piston’s hand 

wheel side, as a balancing force during hand wheel operation. 

For ease of hand wheel operation, the cylinder uses a balancing oil line to allow for oil displacement 

and to oppose discharge pressure forces on the slide valve. Oil fills the control 

cylinder as the slide valve moves toward the discharge end (unload position) and oil empties 

from the control cylinder as the slide valve moves toward the suction end (load position). 

This filtered oil supply also lubricates the piston’s wear bands and sealing ring. 

PAGE 3 - 12 3/02


Ariel recommends using rotor injection oil for control cylinder balancing because this pressure 

is approximately discharge pressure. This pressure balance minimizes the manual 

torque requirement when unloading the compressor. Earlier designs, with balance oil tubed 

from the bearing oil supply resulted in excessive torque requirements when this pressure 

was substantially less than the discharge pressure. 

During operation, compressor oil is always diluted by process gas, similar to a carbonated 

drink. Gas will flash out of the oil as pressure is reduced. The presence of flashed gas in the 

control cylinder can result in a compressible gas pocket in the control cylinder. A large gas 

pocket can generate alternating loads on the hand wheel’s threaded rod that may result in 

galled threads and difficulty adjusting slide valve position. Ariel recommends connection of 

the balance oil tubing to the cylinder’s top port. A top connection acts like a high point vent 

as oil exits the cylinder. The bottom connection can still be used for manual oil draining of 

the control cylinder. Refer to Figure 3-3: for balance oil connection details. 

Crank 

Handle 

Balance Oil 

Connection 

Hand 

Wheel 

Balance 

Piston 

Oil Drain 

Plug Cylinder 

Mounting 

Bolts 

Balance 

Cylinder 

V i Spacer 

Locating 

Dowel 


Plug 

Slide Valve 

�� 

Built In Volume Ratio Changes - Internally Changeable V i 

With an internally changeable volume ratio (V i) slide valve cylinder, the compressor's built in 

V i can be changed by installing the appropriate slide valve. There are four different slide 

valve volume ratios (V i = 2.0, 2.6, 3.5, 4.8) that are interchangeable within each compressor 

model. Control cylinder removal is required to access the slide valve to piston rod bolted 

connection for slide valve replacement. Compressors, equipped with internally changeable 

slide valves, are supplied with a specific slide valve V i to match the initial operating conditions. 

If operating condition changes requiring a change in V i, it will be necessary to purchase 

a new slide valve with the required V i . 

Refer to Section 5 - Maintenance for illustrations and details. 

Lock washer 

and Nut 

20% Position 

Stop 

3/02 PAGE 3 - 13


Built In Volume Ratio Changes - Externally Changeable 

V i 

With an externally changeable volume ratio (V i ) slide valve cylinder, a fixed V i slide valve is 

used but does not have to be changed out as does the internally changeable type. The compressor's 

built in V i can be changed by installing the appropriate external V i spacer (V i = 2.2, 

2.6, 3.5, 4.8), which locates the slide valve (discharge port) at the required volume ratio 

position. Compressors, equipped with externally changeable slide valves, are supplied with 

all shim-spacers and the hardware required to adjust to all V i options. 

Refer to Section 5 - Maintenance for illustrations and details. 

Thrust Balance System 

The thrust balance pressure system provides an adjustable counter thrust force to maximize 

male rotor thrust bearing life. The thrust balance system consists of a tubing line connected 

to discharge pressure, an adjustment valve and a pressure gauge to apply a specific pressure 

to the balance piston mounted on the male rotor's suction end. 

NOTE: FAILURE TO SET THE BALANCE LINE PRESSURE FOR THE CURRENT 

OPERATING CONDITIONS WILL SIGNIFICANTLY DECREASE THE LIFE 

EXPECTANCY OF THE THRUST BEARINGS. ARIEL STRESSES THE IMPOR- 

TANCE OF PROPERLY ADJUSTING AND MAINTAINING THRUST BALANCE 

PRESSURES TO OPTIMIZE MALE ROTOR THRUST BEARING LIFE AND TO 

PREVENT PREMATURE BEARING FAILURE. 

Thrust Balance Pressure Adjustment 

Rotor thrust forces on a rotary compressor are a function of suction pressure, discharge 

pressure and installed volume ratio. Ariel rotary compressors are furnished with a thrust-balancing 

feature that allows the application of an opposing thrust force, through the use of 

adjustable gas pressure against a thrust balance piston. This balance piston is mounted on 

the male rotor’s suction end. When balance gas pressure is applied, bearing thrust is 

reduced. Maintaining a thrust balance pressure appropriate for current operating conditions 

is important to minimize thrust loads and to achieve long term compressor run time. The 

Ariel Rotary Screw Performance program provides target thrust balance pressures. 

A change in compressor thrust force is more dependent on a change in suction pressures 

than on a change in discharge pressures. Maintaining proper thrust balance pressures on 

compressors with a normal operation suction pressure of 30 psig (2.1 bar g ) and higher 

should be given utmost attention. Generally, a slightly higher thrust balance pressure than 

the target pressure is best. Ariel’s target thrust balance pressure is the minimum pressure 

setting for a given set of operating conditions. 

Thrust balance pressure is read on the gauge shown in Figure 3-4:. The pressure is 

adjusted by opening or closing the manual valve. Check the thrust balance pressure as part 

of the daily routine and adjust the pressure to match the target pressure for the current operating 

conditions. 

PAGE 3 - 14 3/02


Thrust Balance 

Pressure Gauge 

Balance Pressure 

Adjustment Valve 

FIGURE 3-4: THRUST BALANCE PRESSURE GAUGE AND ADJUSTMENT VALVE 

Gas/Oil Separator Coalescing Filter - Scavenged Oil Line 

Flow Adjustment 

The gas/oil separator coalescing filter removes residual oil from the discharge gas stream. 

The oil scavenge line is necessary to minimize oil accumulation on the downstream side of 

the coalescing filter. A metering valve, check valve, flow indicator and a 75 micron (0.003 in.) 

strainer or filter are to be located in the scavenged oil line to return the downstream coalescing 

filter oil to the compressor. See Figure 4-1: on page 4-3 and Figure 4-2: on page 4-4. 

With the compressor at normal operating conditions, adjust the valve to show gas flow 

movement into the compressor with minimal oil inclusion. If 100% of coalesced oil is not 

removed from the downstream side of the filter, the oil level will increase. The result is oil 

carry-over due to reduced filter cross-sectional area and excessive gas velocity through the 

filter. Excessive scavenged gas flow will reduce compressor performance due to the recycled 

gas. Insufficient scavenged oil flow will reduce coalescing filter performance resulting in 

oil carry-over with discharge gas stream. 

Sour Gas Service with over 100 ppm to 2% H 2 S or Other 

Dangerous Gases 

It is not recommended that single seal Ariel rotary screw compressors be used in Sour Gas 

Service with over 100 ppm H 2S or other dangerous gas service. Single seal Ariel rotary 

screw compressors may not be used in Sour Gas Service over 2% H 2 S. 

3/02 PAGE 3 - 15


If an Ariel rotary screw compressor is used in H 2 S sour gas (between 100 ppm to 2%) or 

other dangerous gas service, it is the responsibility of the end user to provide all the necessary 

safety equipment, procedures and training to protect personnel from gas leakage. 

When operating Ariel Rotary compressors in dangerous gas service, at shutdown the compressor 

must be immediately blown down to remove all dangerous gases, i.e. vented, and/or 

purged with a non-toxic gas to prevent danger to personnel. 

Compressor Re-Application 

NOTE: IF ANY OF THE CONDITIONS LISTED BELOW CHANGE, CONSULT YOUR 

PACKAGER AND/OR ARIEL FOR ANY HARDWARE AND/OR DOCUMENTA- 

TION CHANGES THAT ARE REQUIRED. PERFORMANCE, VOLUME RATIO, 

OIL PUMP FLOW AND LUBE OIL RATE MUST BE RE-CALCULATED. 

1. Gas pressures, temperatures or flow requirements. 

2. Gas properties. 

3. Driver type, speed or torque. 

4. Re-location of compressor to a different site. 

PAGE 3 - 16 3/02


SECTION 4 - OIL SYSTEM, LUBRICATION & 

VENTING 

General 

The oil system is vital for successful operation of rotary screw compressors and deserves 

special attention in the package design and operation. Ariel oil flooded rotary screw compressors 

utilize a pressurized, filtered, recirculation oil system. Oil is supplied to the compressor 

thorough rotor injection and various oil connections. 

Oil flooding of the compression chamber is supplied at rotor injection. Pumped oil supplies 

lubrication to the bearings, oil to the mechanical seal and provides hydraulic power to position 

the slide valve. Pumped oil is scavenged in the compression chamber at an internal 

pressure less than rotor injection. The compressor oil system provides the following major 

functions: 

1. Seals the internal running clearances and mechanical seal. 

2. Absorbs the heat of compression. 

3. Lubrication of rotors, bearings and mechanical seal. 

4. Hydraulic power - to move slide valve. 

The process gas will dilute the oil, both mineral and synthetic, resulting in reduced viscosity. 

The pressurized oil viscosity reduction can be predicted and will remain stable provided that 

gas composition, pressure and temperature do not change and that any liquids are effectively 

removed from the gas prior to compressor suction. 

Careful consideration must be given to proper lubrication selection. The degree of compressor 

oil dilution/saturation by the process gas stream is influenced by the following factors: 

1. Process gas composition/Specific Gravity (SG) - usually the higher the SG, the 

greater the oil dilution. 

2. Discharge gas pressure - the higher the pressure, the greater the oil dilution. 

3. Discharge gas temperature - the higher the gas/oil separator reservoir temperature, 

the less the oil dilution. 

4. Lubricant selection - some oil types are more prone to dilution. 

Lubricants commonly used in oil flooded rotary compressors include petroleum based oils 

and synthetic fluids. Lubricant additives are used to improve the viscosity index, inhibit oxidation, 

depress the lubricant pour point, inhibit rust formation, improve detergency, provide 

anti-wear protection, provide extreme pressure protection, improve “lubricity”, decrease 

effects of gas dilution, increase “wetability”, and resist “washing” of the lubricant due to 

water, wet or saturated gas, or dilutive properties of the gas stream. 

Viscosity index is a measure of the ability of an oil to resist the thinning effect caused 

• 

by increasing the oil temperature. 

3/02 PAGE 4 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 4 - OIL SYSTEM, LUBRICATION & VENTING 

• Lubricity is the “slipperiness” or ability of a lubricant to decrease friction. 

Wetability is a measure of the ability of the lubricant to adhere to metal surfaces. An 

• 

increase in wetability increases the lubricants’ resistance to “washing” effects. 

Pressure gauges are required for monitoring pressure drop across all oil filters. 

Compressor oil should be changed at regular maintenance intervals or when oil sample 

results indicate the need. A more frequent oil change interval may be required if operating in 

an extremely dirty environment or if the oil supplier recommends it. Oil sampling should be 

performed on a regular basis to verify suitability of oil for continued service. Degradation to 

the next lower viscosity grade below the original viscosity or an increase in viscosity to the 

next higher grade requires a complete oil change. 

NOTE: THESE OIL RECOMMENDATIONS ARE GENERAL GUIDELINES. IF THE REC- 

OMMENDED LUBRICANTS OR FLOW RATES DO NOT APPEAR TO WORK 

ADEQUATELY, FLOW RATES AND/OR LUBRICANT TYPES MAY NEED TO BE 

CHANGED. PLEASE CONTACT THE OIL SUPPLIER FOR SPECIFIC LUBRI- 

CANT RECOMMENDATIONS. 

Lubricants 

It is not Ariel’s policy to recommend any particular type or brand of oil. There are many companies 

who specialize in recommending blended or synthetic oil for a given application. 

These consultants given the gas composition analysis and operating conditions conduct 

proprietary flash gas and dilution calculations to determine proper lubrication and heat 

removal, as well as oxidation inhibition, rust and corrosion inhibition, and anti-wear properties. 

Use of an experienced reliable lubricant consulting service is recommended. 

Compressor bearings are designed to operate with an optimum kinematic viscosity of 112 

SUS (23 cSt) at compressor casing oil inlet port. 

The minimum kinematic viscosity at operating conditions is 80 SUS (15 cSt). Com- 

• 

pressor operation with oil viscosity below 112 SUS (23 cSt) will cause lubrication and 

sealing deterioration. 

The maximum kinematic viscosity at operating conditions is 142 SUS (30 cSt). 

• 

Once a rotary compressor oil viscosity is selected, operating viscosity is affected by temperature 

and pressure in the gas/oil separator, plus ingested liquid contaminants in the suction 

gas stream. 

Additives must not be corrosive to lead or copper base bearing materials. 

Automatic transmission fluids (ATF) and used engine oils are not to be used for rotary compressor 

oils. 

PAGE 4 - 2 3/02


Lube 

Oil 

To Mech 

anical 

Seal w/ 

Orifice 

FIGURE 4-1: TYPICAL LUBE OIL SYSTEM - HYDRAULIC SLIDE VALVE CONTROL CYLINDER 

TABLE 4-1: ILLUSTRATION LEGENDS FOR FIGURE 4-1 

GAS CONNECTIONS OIL CONNECTIONS PUMP CONNECTIONS INSTRUMENTATION SYSTEM COMPONENTS 

A1. Suction Flange 

A2. Discharge Flange 

Load 

B1. Main Oil Supply 

B2. Rotor Oil Injection 

- Female 


- Male 

B4. Scavenge Oil 

B5. Mechanical 

Seal/Thrust Bearing 


High Lo 

To Scavenger 

From 

Separator 

P1. Oil Pump Suction 

P2. Oil Pump Discharge 

Slide Valve Hydraulic 

Cylinder 

Ariel Twin Screw 

Rotary Compressor 

To Rotor 

Injection 

PI. Pressure Indicator 

PDSLL. Pressure 

Differential Switch 

LoLo - Oil Supply 

TE. Temperature 

Element 

TSHH. Temperature 

Switch - HiHi (Oil 

Supply/Discharge) 

Process 

Gas 

Suction 

Piping 

By Ariel 

Gas/Oil 

Separator 

Oil Cooler 

1. Inlet Scrubber 

2. Check Valve 

3. Strainer - Conical, 

Gas 

4. Shutoff Valve 

5. Flow Indicator 

6. Relief Valve 

7. Pressure Control 

Valve 

8. Needle Valve - Flow 

Control 

9. Prelube Pump 

10. Integral Oil Pump- 

Female Rotor Drive 

Piping 

By Pkgr. 

Vent to 

Safe 

Atmosphere 

Process 

Gas Discharge 

11. Coalescing Filter 

12. Differential Pressure 

Gauge/Indicator 

13. Oil Filter 

14. Orifice 

15. Temp Control Valve 

16. Back-Pressure Control 

Valve 

17. Unload Valve - Oil In 

18. Loading Valve - Oil 

Out 

19. Oil Strainer-60 Mesh 

20. Trim Valve - Temp 

Control Valve 

3/02 PAGE 4 - 3


Lube Oil 

To Mechanical 

Seal w/ Orifice 

FIGURE 4-2: TYPICAL LUBE OIL SYSTEM - HAND WHEEL SLIDE VALVE CONTROL 

TABLE 4-2: ILLUSTRATION LEGENDS FOR FIGURE 4-2 

GAS CONNECTIONS OIL CONNECTIONS PUMP CONNECTIONS INSTRUMENTATION SYSTEM COMPONENTS 

A1. Suction Flange 

A2. Discharge Flange 

Slide Valve 

Hand Wheel 

Cylinder 

B1. Main Oil Supply 


- Female 


- Male 

B4. Scavenge Oil 

B5. Mechanical Seal/ 

Thrust Bearing Oil 

To Slide Valve 

Cylinder - Balance 

Line - 

Bi-Directional 

Oil Flow 

To 

Scavenge 

From 

Separator 

P1. Oil Pump Suction 

P2. Oil Pump Discharge 

Ariel Twin Screw 

Rotary Compressor 

To Rotor 

Injection 

PI. Pressure Indicator 

PDSLL. Pressure Differential 

Switch LoLo - 

Oil Supply 

TE. Temperature Element 

TSHH. Temperature 

Switch - HiHi (Oil Supply/Discharge) 

Process Gas Suction 

Gas/Oil 

Separator 


Piping 

By Ariel Piping 

By Pkgr. 

Vent to 

Safe 

Atmosphere 

Process 

Gas Discharge 

1. Inlet Scrubber 

2. Check Valve 

3. Strainer - Conical, 

Gas 

4. Shutoff Valve 

5. Flow Indicator 

6. Relief Valve 

7. Not Used 

8. Needle Valve - Flow 

Control 

9. Prelube Pump 

10. Integral Oil Pump - 

Female Rotor Drive 

11. Coalescing Filter 

12. Differential Pressure 

Gauge/Indicator 

13. Oil Filter 

14. Orifice 

15. Temperature Control 

Valve 

16. Back-Pressure Control 

Valve 

17. Not Used 

18. Loading Valve - Oil 

Out 

19. Oil Strainer - 60 Mesh 

20. Trim Valve - Temperature 

Control Valve 

PAGE 4 - 4 3/02


Petroleum Based Oils - also referred to as mineral oils: 

Paraffinic - higher wax content, better resistance to thinning at higher operating temperatures 

than napthenic. 

Napthenic - (as compared to paraffinic) lower wax content, better flowability at low temperatures 

for cold start-ups, lower resistance to thinning at higher operating temperatures, better 

solvency, lower life/oxidation stability. 

Animal fat and vegetable oil additives are not be used in rotary screw compressors. 

Synthetic Lubricants 

Synthetic lubricants are man-made materials with more consistent, controlled chemical 

structures than petroleum lubricants. This improves predictability of viscosity and thermal 

stability. Synthetic lubricants can be designed with better dilution resistance, better oxidation 

resistance, better lubricity, better film strength, natural detergency, lower volatility, and 

results in decreased operating temperatures. These attributes can help to decrease rotor 

injection feed rate requirements. Justification for the use of synthetic lubricants is based on 

energy savings, reduced lubricant usage, increased component life, decreased equipment 

downtime, and reduced maintenance/labor. Some synthetic lubricants can be used in the 

compressor lubrication. Consult with the lubricant supplier before using these lubricants in 

the compressor. 

• 

• 

Synthesized Hydrocarbons - polyalphaolefins (PAO) can be used as compressor 

lubricants: 

1. Compatible with mineral oils. 

2. Compatible with viton. 

3. Generally not water soluble. 

4. Diluted by heavy hydrocarbon gases. 

5. Requires additives to improve detergent action and improve seal compatibility. 

6. Soluble in some gases. Verify application with lubricant supplier. 

7. Compatible with Viton and HNBR - Buna N (high end acrylonitrile-butadiene). 

Organic Esters - diesters and polyolesters: 

1. Compatible with mineral oils 

2. Incompatible with some rubbers (O-rings), plastics, and paints. Compatible with 

Viton. 

3. Primarily used in air compressors. 

• Polyglycols - polyalkylene glycols (PAG), polyethers, polygylcolethers, and polyalkylene 

glycol ethers: 

1. Not compatible with mineral oils, some plastics and paints. Requires complete 

system flush when changing to or from polyglycols. Contact oil supplier 

for flushing details. 

2. Can be water soluble - must verify application with lubricant supplier. 

3. Resistant to hydrocarbon gas dilution. Excellent wetability. 

4. Poor inherent oxidation stability and corrosion protection - requires additives. 

3/02 PAGE 4 - 5


5. Compatible with Viton and HNBR - Buna N (high end acrylonitrile-butadiene). 

6. Not recommended for air compressors. 

Auxiliary Equipment 

Lube Oil Strainer 

The strainer is located between the pump suction and the oil cooler. The strainer basket 

should be taken out and washed in an appropriate solvent whenever the lubricating oil is 

changed. 


All compressors must have an oil cooler. Maximum allowable oil temperature into the compressor 

is determined by the process gas dew point, operating conditions and the type of oil. 

Oil temperature into the compressor is recommended to be 150°F (65°C). The packager is 

responsible for sizing a proper oil cooler. Operating conditions which must be taken into 

account are; the cooling medium, cooling medium temperature, cooling medium flow rate, 

lube oil temperature, lube oil flow rate, gas temperatures and gas compression capacities. 

Oil heat rejection data for each application is determined from the Ariel Rotary Compressor 

Performance Program (contact your Packager or Ariel when you need this information). 

The cooler should be mounted as close to the compressor as possible, with piping 

of adequate size to minimize pressure drop of both the oil and the cooling medium. 

Temperature Control Valve 

For proper operation of the oil system a temperature control valve is required. The maximum 

differential pressure between the hot oil supply line (point B) and the cooled oil return line 

(point C) is to be 10 psi (0.7 bar). Refer to Figure 4-1: Ariel recommends installation of the 

temperature control valve in the mixing mode. 

The recommended oil injection temperature is 150°F (65°C) at the compressor oil inlet ports. 

An oil temperature of 150°F (65°C) is the minimum temperature required to drive off water 

vapor. Normally select a temperature control valve with a 150°F (65°C) nominal temperature 

setting. If operating conditions dictate otherwise, contact Ariel Application Engineering (refer 

to “Ariel Contact Information” on page7-10 for contact information. 

Cold Ambient Temperatures 

If a compressor is exposed to cold ambient temperatures, the oil system must be designed 

so the unit may be safely started with adequate oil flow to the compressor bearings and 

mechanical seal. Temperature controlled cooler by-pass valves, oil heaters, cooler louvers 

and even buildings may be needed to assure successful operation. 

Oil filter differential pressure increases significantly with oil viscosity greater than 2275 SUS 

(500cSt). The maximum viscosity of the lube oil for cold ambient temperature starting with- 

PAGE 4 - 6 3/02


out pump cavitation is 7,275 SUS (1600 cSt) provided that all external piping is heat traced 

and insulated. Minimum start up temperatures for full or semi-synthetic lubricants can be 

reduced based on viscosity index. Start up oil viscosity must be sufficiently low to prevent 

pump, filter, bearing or mechanical seal damage. 

When electric oil immersion heaters are used with mineral oils, the watt density of the heater 

element should not exceed 5 watts per square inch (0.8 W/cm 2 ) for systems without circulating 

pumps. Oil coking will occur at the element with higher wattage heaters if a circulating 

pump is not used. When high wattage heaters are required, the heaters must be interlocked 

with an oil circulation pump to assure that coking of the oil will not occur. Coked oil will form 

deposits which can “insulate” the system and decrease heat removal. The deposits can also 

break loose and act as abrasives in the lubricating system. Synthetic oils may have higher 

coking temperature limits, contact your lubrication supplier for details. 

Prelube Pump 

Rotary compressors must have a prelube pump, to ensure bearing and mechanical seal oil 

flow, to refill oil filters after maintenance and to position the slide valve to 0% load prior to 

start-up, when hydraulic control cylinder equipped. 

NOTE: THE MECHANICAL SEAL IS DESIGNED TO OPERATE WITH AN OIL FILM AND 

MUST BE PRE-LUBED PRIOR TO STARTING. THE SEAL MUST BE CONTI- 

NOUSLY SUPPLIED WITH OIL WHILE COMPRESSOR IS OPERATING. ANY 

DRY RUNNING OF SEAL, WITHOUT LUBRICATING OIL, WILL RESULT IN 

SCORING OF THE SEAL FACES AND REDUCED SEAL LIFE. 

Oil Pressure Regulating Valves 

The oil pump is generally capable of supplying oil pressure and volume in excess of that 

required for a specific application. The pressure regulating bypass valve across the oil pump 

is used to supply an adequate oil volume to bearings, mechanical seal and hydraulically 

controlled slide valve cylinder, if so equipped, while bypassing the excess oil volume. A 

hydraulically controlled slide valve requires a minimum oil pressure approximately 45 psi 

(3.1 bar g) above discharge pressure to unload the slide valve. 

The second oil pressure regulating valve, used only with hydraulically controlled slide valve 

cylinders, reduces oil pressure for the bearings and seal while providing a back pressure for 

the hydraulic oil supply. Adjustments to the oil pressure regulating valve settings allow Ariel 

rotary compressors to be applied for a wide variety of operating conditions. Refer to “Compressor 

Oil Supply Pressure Calculations” on page 4-9 to determine proper settings. 

Oil Filters 

Ariel recommends replacing filter elements before differential pressure reaches collapse 

pressure across the filter at normal operating temperatures or at six month intervals. 

3/02 PAGE 4 - 7


Bearing, mechanical seal and control cylinder full flow filtration shall equal or exceed a 7 µm 

(micron) rating with a 75 Beta ratio (B 7 = 75, 98.7% efficiency rating at removing 7 µm and 

larger particle size. 

Rotor injection full flow filtration shall equal or exceed a 15 µm (micron) rating with a 75 Beta 

ratio (B 15 = 75, 98.7% efficiency rating at removing 15 µm and larger particle size. 

NOTE: FAILURE TO FILL FILTER VESSELS WITH OIL PRIOR TO STARTING, AFTER 

CHANGING FILTERS, CAN CAUSE SEVERE DAMAGE TO THE COMPRES- 

SOR. 

Liquids and Contaminants in Gas 

The use of higher viscosity lubricants or specially compounded lubricants can compensate 

somewhat for the presence of liquids in the gas stream. 

NOTE: WHEN THERE ARE FREE LIQUIDS AND CONTAMINANTS PRESENT IN THE 

GAS, THE MOST EFFECTIVE LUBRICATION OF ROTARY COMPRESSORS 

REQUIRES REMOVAL OF THE LIQUIDS AND CONTAMINANTS BY USING 

SCRUBBERS BEFORE THE GAS ENTERS THE COMPRESSOR. 

To minimize compressor oil dilution, the gas/oil separator operating temperatures should be 

maintained about 20F° (11C°) above the process gas dew point temperature at discharge 

pressure, but not less than 150°F (65°C). A separator temperature of 150° (66°C) is the minimum 

temperature required to drive water vapor into the process gas stream. 

Compressor Oil Pump 

For compressor oil pump sizing and flow verification, refer to the Ariel Performance Program. 

The compressor integral oil pump is sized for the driver-compressor package speed range 

and gas application pressures, to provide adequate oil flow and pressure for the compressor 

within the driver’s normal speed range. Generally, minimum driver speed is based upon a 

speed versus horsepower or torque lug curve that determines compressor and oil pump 

minimum speeds. 

The compressor oil pump is selected to provide adequate lubricating oil and slide valve positioning 

hydraulic pressure at minimum driver speed and maximum compressor differential 

pressure. The integral compressor oil pump is direct driven by the female rotor, which has a 

lower rotating speed than the male rotor. Oil pump flow and pressure are determined by 

female rotor speed and oil pressure regulating valve adjustment. 

PAGE 4 - 8 3/02


Male and female rotor speed limitations are as follows, in Table 4-3:, below. Minimum operation 

drive speed to the compressor must not be less than the minimum male rotor speed 

limit. 

TABLE 4-3: ROTOR SPEED LIMITS 

COMPRESSOR 

MODEL 

Minimum bearing oil supply pressure and shutdown setting are based upon the differential 

pressure connection to the scavenged oil gallery. Refer to “Lube Oil Shutdowns” on page 4- 

10 for additional lube oil shutdown information. 

Compressor Oil Supply Pressure Calculations 

The compressor oil flows are based upon fixed internal clearances, except for mechanical 

seal supply which uses a fixed external orifice, supplied by Ariel. Adequate compressor oil 

flow is based upon measured oil pressure at the compressor connections. 

Listed below are the minimum compressor oil pressure requirements: If control cylinder or 

bearing oil pressures cannot be met, contact your Packager or Ariel. 

Where: Ps = Suction Pressure, absolute 

Pd = Discharge Pressure, absolute 

k = Ratio of Specific Heats for Process Gas in Service 

1 psia = 1 psig + atmospheric pressure at elevation 

1 (bar a ) = 14.5 psi 

ROTOR GEAR 

RATIO, MALE 

LOBES/FEMALE 

FLUTES 

1. Slide Valve Control Cylinder Hydraulic Pressure (SVCP), minimum = Pd + 43.5 

psia (or + 3 bara ) 

Example: If, Pd = 75 psia (5.2 bara ), 

SVCP = 75 + 43.5 = 118.5 psia 

SVCP = 5.2 + 3 = (8.2 bar a ) 

MINIMUM ROTOR 

SPEED, RPM 

MALE/FEMALE 

2. Bearing Oil Pressure (BOP), minimum = 1.5 Ps + 72.5 psi (or + 5 bara) Example: If, Pd = 75 psia (5.2 bara), Ps = 25 psia (1.7 bara) BOP = (1.5 x 25) + 72.5 = 110 psia 

BOP = (1.5 x 1.7) + 5 = (7.6 bar a ) 

MAXIMUM ROTOR 

SPEED, RPM 

MALE/FEMALE 

AR166 5/7 1148/820 5739/4099 

AR208 5/7 918/656 4591/3279 

AR260K, AR260 5/7 735/525 3550/2366 

3/02 PAGE 4 - 9


3. Rotor Injection Pressure, approx. (RIP) = Ps x (1.9) k 

Actual flow/pressure fluctuates with changes in bearing oil pressure. 

Example: If, Ps = 25 psia (1.7 bar a), k = 1.2 

RIP = 25 x (1.9) 1.2 = 25 x 2.16 = 54 psia 

RIP = 1.7 x (1.9) 1.2 = 1.7 x 2.16 = (3.7 bar a) 

Gas Balance Line Pressure (GBLP) Calculation 

Ariel rotary compressors use regulated discharge gas pressure to provide a counter thrust 

force that reduces bearing load on the male rotor active thrust bearing. A minimum gas balance 

pressure is determined by the Ariel Rotary Compressor Performance Program for an 

operating condition. Properly monitored and adjusted gas balance pressure is required to 

maximize thrust bearing life. 

Example: If, Ps = 25 psia (1.7 bar a ), Pd = 75 psia (5.2 bar a ) at 1700 RPM 

GBLP = 54 psig minimum 

GBLP = (3.5 bar g) 

Compressor Re-Application 

NOTE: IF ANY OF THE CONDITIONS LISTED BELOW CHANGE, CONSULT YOUR 

PACKAGER AND/OR ARIEL FOR ANY HARDWARE AND/OR DOCUMENTA- 

TION CHANGES THAT ARE REQUIRED. PERFORMANCE AND OPERATING 

PRESSURES MUST BE RE-CALCULATED: 

1. Gas pressures, temperatures or flow requirements. 

2. Gas properties. 

3. Driver Type, speed or torque. 

4. Re-location or compressor to a different site. 

Warranty 

Warranty of component failures which occur while using lubricants which do not meet these 

specifications will be subject to review on a case by case basis. 

Lube Oil Shutdowns 

NOTE: THE COMPRESSOR MUST HAVE WORKING LOW OIL PRESSURE AND HIGH 

INLET OIL TEMPERATURE SHUTDOWNS. 

PAGE 4 - 10 3/02


Pressure: 

Inadequate oil pressure and flow can cause catastrophic compressor damage. 

Minimum bearing oil supply pressure alarm and shutdown settings are based upon the differential 

pressure connection to the scavenge oil gallery. The low differential oil pressure 

shutdown switch (low, low - PDSLL) is normally supplied and installed by the packager with 

a low side sensing connection into the scavenge oil gallery. 

The normal bearing oil pressure is a value greater than 1.5P s + 72.5 psi (+ 5 bar a), see previous 

examples at Bearing Oil Pressure (BOP) in “Compressor Oil Supply Pressure Calculations” 

on page 4-9. 

The bearings require a minimum oil supply pressure approximately 75 psig (5 bar g) higher 

than the downstream (scavenge oil gallery) pressure to maintain adequate oil flow for lubrication 

and cooling. To maintain adequate flow during upset conditions, a shutdown setting of 

approximately 60 psig (4+ bar g ) falling pressure is recommended. See Figure 4-3: for an 

illustration of the connection points using a differential pressure shutdown (low, low - 

PDSLL). 

Bearing Oil Supply 

PDSLL, High Side 

1/4” Tubing 

FIGURE 4-3: DIFFERENTIAL PRESSURE SWITCH, LOW-LOW (PDSLL) 

Scavenge Oil Gallery 

PDSLL, Low Side 

3/02 PAGE 4 - 11


Ariel recommends the oil pressure switch be set to actuate when oil pressure falls below the 

following pressures: 

Normal oil pressure > 1.5 x Ps + 72.5 psi (= 1.5 x Ps + 5 bar a ) 

Alarm, psid = (1.5 x Ps + 65 psi), falling 

[Alarm, bar d = (1.5 x Ps + 4.5 bar a ), falling] 

Shutdown, psid = (1.5 x Ps + 58 psi), falling 

[Shutdown, bar d = (1.5 x Ps + 4 bar a ), falling] 

Temperature: 

The high oil temperature shutdown is to be located at the filter inlet connection. It is to be set 

10% above normal oil inlet temperature. 

Rotor Injection Flow 

Rotor injection oil pressure and flow are a function of operation conditions, specifically suction 

and discharge pressures and temperatures. See the Ariel Performance Program - generated 

summary sheet for required rotor injection oil flow and gas discharge temperature for 

given operating conditions. Adjust rotor injection flow throttling valve to maintain the required 

minimum discharge gas temperature. 

Reducing rotor injection flow will raise discharge gas and oil/gas separator temperature. 

Consult Ariel Application Engineering before reducing oil flow volume. 

Flushing Requirements 

Some synthetic and mineral based oils are not compatible. Use extreme care and refer to oil 

suppliers recommendations for draining and flushing the oil system when changing to or 

from a synthetic oil. 

The compressor is tested at the factory using a synthetic - mineral based oil and prior to 

shipment protected with a vapor phase inhibitor in a mineral oil. These oils may not be compatible 

with the oil selected for field use. Consult the oil supplier to determine if clean-out 

flushing is required. 

PAGE 4 - 12 3/02


SECTION 5 - MAINTENANCE 

General Introduction 

The major components of the compressor are the rotor housing, discharge housing, rotors, 

bearings, mechanical seal, slide valve, thrust balance piston, oil pump and hydraulic slide 

valve control cylinder with slide valve position indicator (or slide valve control cylinder with 

hand wheel). The mechanical seal, slide valve, slide valve spacers, slide valve position indicator, 

and oil pump and coupling may be replaced in the field. 

NOTE: DO NOT OTHERWISE DISASSEMBLE THE INTERNALS OF THE COMPRES- 

SOR. IF OTHER INTERNAL COMPONENTS NEED REPAIR, RETURN COM- 

PRESSOR TO ARIEL FOR OVERHAUL OR EXCHANGE. 

Absolute cleanliness, including the use of lint-free wiping cloths, is a necessity during any 

maintenance on the compressor. When access covers have been removed, keep the compressor 

covered to protect the internal surfaces from debris except when actually working 

within it. Any components that have been removed should be protected from falling objects 

that might mar or chip machined surfaces. 

Whenever the compressor is dismantled, o-rings at non-pressure positions are to be carefully 

inspected before reuse, if damaged they should be replaced. O-rings at pressure locations 

should be replaced. O-ring lubricants must be compatible with o-ring materials, lube oil 

and process gas. 

! 

CAUTION 

TO PREVENT PERSONAL INJURY, ASSURE THAT COM- 

PRESSOR ROTOR CANNOT BE TURNED BY THE DRIVER OR 

GAS PRESSURE DURING MAINTENANCE: -- ON ENGINE- 

DRIVEN COMPRESSORS, REMOVE THE CENTER COUPLING 

OR LOCK THE FLYWHEEL. -- ON ELECTRIC MOTOR-DRIVEN 

COMPRESSORS, IF IT IS INCONVENIENT TO DETACH THE 

DRIVER FROM THE COMPRESSOR, THE DRIVER SWITCH 

GEAR MUST BE LOCKED OUT DURING MAINTENANCE. 

BEFORE STARTING ANY MAINTENANCE OR REMOVING 

ANY COMPONENTS, RELIEVE ALL PRESSURE FROM THE 

COMPRESSOR GAS AND OIL SYSTEMS. (SEE PACKAGER’S 

INSTRUCTIONS FOR COMPLETELY VENTING THE SYSTEM. 

3/02 PAGE 5 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 5 - MAINTENANCE 

Mechanical Seal 

! 

CAUTION 

AFTER PERFORMING ANY MAINTENANCE, THE ENTIRE 

SYSTEM MUST BE PURGED WITH GAS PRIOR TO OPERA- 

TION, TO AVOID A POTENTIALLY EXPLOSIVE AIR/GAS MIX- 

TURE. 

Seal Housing 

Spacer Ring 

Rotating 

Seal - Inner 

Ring 

O-Ring 

O-Ring 

O-Ring 

Capscrew 

FIGURE 5-1: MECHANICAL SEAL TOP VIEW - TYPICAL 

Stationary Carbon 

Seal - Spring 

Loaded Assembly 

Clamping 

Spacer 

Discharge 

Cover 

Shaft Seal 

Lock Nut 

Male Rotor 

Drive End 

Silicon Caulk - 

Thread Protection 

Anti-Rotation Pin 

(AR166 & 208 Only) 

Seal 

Housing 

The mechanical seal prevents loss of internal process gas pressure, at the male rotor drive, 

around the shaft to the compressor exterior. The seal consists of a rotating inner ring which 

turns with the rotor and a spring loaded carbon seal assembly which is held stationary in the 

seal housing cover. Sealing is generated by the spring force and the hydraulic force of the 

lubricating oil pressure acting on the seal faces. 

On compressor Models AR260 and AR260K, the mechanical seal’s stationary cartridge has 

no anti-rotation pin. 

PAGE 5 - 2 3/02


On compressor Models AR166 and AR208, the mechanical seal’s stationary cartridge has 

an anti-rotation pin and can only be installed one way. 

To install the rotating ring, pull it up against the shaft stop with clamping spacer. To install 

stationary cartridge into housing, use special tool. To install the mechanical seal housing, 

use a torque pattern to pull up square. 

Thoroughly clean silicon thread caulk from the shaft. During reassembly, any caulk residue 

will be sheared by the clamping spacer and gunk may be forced into the seal’s contact face. 

Do not use the shaft seal locknut as a holding (reaction) point when removing the coupling 

hub’s collared retaining bolt. Excessive tightening will buckle the thin-walled clamping 

spacer. 

The mechanical seal must be kept free of oil and oily fingers. Oil attracts debris which can 

score the surfaces resulting in leaks and reduced service life. 

NOTE: MECHANICAL SEAL CRITICAL SURFACES SUCH AS SEAL FACES, O-RING 

SEATS AND FITS MUST BE HANDLED WITH EXTREME CARE. REPLACE- 

MENT SEAL COMPOMENTS MUST BE TRANSPORTED AND STORED IN THE 

ORIGINAL UNOPENED PACKAGING. REPLACEMENT SEALS WHICH HAVE 

BEEN SUBJECT TO IMPACT, SUCH AS BEING DROPPED, ARE NOT TO BE 

USED. STORAGE MUST BE DRY, DUST FREE AND AT REASONABLE CON- 

STANT TEMPERATURE. SEALS STORED IN EXCESS OF THREE YEARS 

SHOULD BE RE-INSPECTED BEFORE BEING USED. DO NOT DISSASSEM- 

BLE THE SEAL - SPRING LOADED ASSEMBLY. 

TABLE 5-1: SEAL AND SEAL HOUSING COVER APPROXIMATE WEIGHTS 

MODEL 

Replacing the Mechanical Seal 

SEAL COVER 

LB (kg) LB (kg) 

AR166 5 (2) 15 (7) 

AR208 9 (4) 25 (12) 

AR260K, AR260 11 (5) 44 (20) 

Remove thread protection caulking compound, located between the shaft seal lock nut and 

coupling hub, being careful not to damage threads. Hold rotor from turning, with drive train 

assembled coupling in place, and loosen the shaft seal locknut, using the special spanner 

wrench provided in the tool box (see Table 7-1: on page 7-2). Heating lock nut to 200°F maximum 

(93°C) may be required to break Loctite seal. Disassemble the coupling center section 

and remove the coupling hub half and retaining bolt from the male rotor. Remove the shaft 

seal lock nut. Remove the 12 point cap screws that secure the seal housing cover to the discharge 

cover. Using the two jack bolts (M12 x 1.75 x 40mm or M16 x 2 x 55mm, class 12.9) 

provided in the tool box, jack seal housing cover loose. Slide the seal housing cover and 

clamping spacer off the rotor. 

NOTE: BE CAREFUL TO PROTECT THE ROTOR THREADS FROM DAMAGE WHEN 

REMOVING AND INSTALLING MECHANICAL SEAL. 

3/02 PAGE 5 - 3


Remove the inner seal ring and o-ring from the rotor. 

Disassemble the seal housing cover internal parts, removing the spacer ring, seal - spring 

loaded assembly, both o-rings and jack bolts. Discard both mechanical seal elements, all 

three o-rings and lock nut. Clean parts, being careful to remove Loctite residue from rotor 

threads, external and internal, and coupling retaining bolt threads. 

Reassemble using a new mechanical seal, three new o-rings and new lock nut. Lubricate orings 

with a high viscosity silicone fluid such as Parker Super-O-Lube or equal. Put o-ring 

and inner seal ring in position on rotor. On the AR166 and AR208 compressors, the seal - 

spring loaded assembly utilizes a dowel to help hold it stationary in the seal housing. This 

dowel normally does not need to be replaced. Replace both o-rings on the seal housing. 

Press seal - spring loaded assembly into seal housing. A cylindrical ring fixture to push 

against the seal housing provided in the Ariel tool box is required. Do not push against seal 

face or tap into place. Reassemble spacer ring and clamping spacer into seal housing. 

Slide seal housing on to rotor, being careful to position leakage weep hole downward while 

aligning bolting holes. Install cap screws and tighten to torque values in Table 1-3 on Page 

5-10. 

Apply Loctite grade 222 (purple) to the first two external rotor shaft threads and assemble 

nut on to rotor, hand tight. Quickly, temporarily reassemble drive coupling hub and key, hand 

tight. Hold coupling hub to keep rotor from turning and tighten the shaft seal locknut, using 

the special wrench provided in the tool box to the proper torque value in Table 1-4 on Page 

5-10. Working time for Loctite 222 is 10 minutes. Reassemble complete coupling to manufacture’s 

instructions. Apply a bead of silicone caulking compound at the shaft to seal lock 

nut face covering all of the exposed shaft threads to help protect from impact damage and 

thread corrosion. 

NOTE: THE COUPLING RETAINING BOLT TORQUE IS BASED UPON COUPLING 

DESIGN AND THE POWER TO BE TRANSMITTED. CONSULT PACKAGER’S 

INFORMATION FOR PROPER TORQUE VALUE. 

Optional Collared Retaining Bolts 

Ariel offers an optional Collared Retaining Bolt (CRB) for reduced torque compressor applications. 

The CRB replaces the standard bolt and washer retaining bolt design that was originally 

developed for high horsepower applications that require the use of a special coupling 

hub design. 

The CRB is a low profile design for use on AR Series rotary compressor drive coupling hubs. 

It minimizes the coupling hub counterbore depth for selected coupling designs and allows 

the use of the standard, semi-finished coupling hubs that are typical for reduced torque, natural 

gas applications. 

Refer to Ariel’s Engineering Reference ER-41 “Rotary Compressor - Coupling Hub Installation 

& Retention” for details and application limitations for the use of CRBs. 

Installation and removal of the CRB requires the use of an Ariel supplied torquing adapter 

tool. This tool adapts to standard 1/2” and 3/4” drive torque wrenches and applies torque 

PAGE 5 - 4 3/02


using dowel pins. (Refer to Figure 5-2: Collared Retaining Bolt Assembly and Figure 5-3: 

Mechanical 

Seal Lock Nut 

FIGURE 5-2: COLLARED RETAINING BOLT ASSEMBLY 

Collared Retaining Bolt and assembly Tool.) 

Collared 

Retaining 

Bolt 

Assembly 

Tool 

Shaft Key 

Male Rotor Shaft 

Coupling Hub 

Collared 

Retaining 

Bolt 

FIGURE 5-3: COLLARED RETAINING BOLT AND ASSEMBLY TOOL 

3/02 PAGE 5 - 5 

2° 

51’ 

45” 

Opening 

Sized for 

3/4” Drive 

Ratchet


Slide Valve Replacement - Internally Changeable V i 

The slide valve may be changed, to provide a different volume ratio (V i ) that is appropriate 

for current operating conditions. 

To replace the slide valve, move the slide valve to the full load (100%) position. The male 

rotor must be rotated so that the shaft keyway is at the top (12 o’clock position), which positions 

rotor mesh for ease of slide valve cylinder assembly removal and reinstallation. Be 

sure that the compressor is properly vented and that the equipment is locked out so rotors 

can not turn. Remove oil lines from slide valve cylinder, and rotor housing drain plug to drain 

residual oil. Replace drain plug when oil stops running. Unbolt slide valve indicator or 

remove electrical connection, as required, to allow for slide valve cylinder removal. 

Axial Position 

Indicator 

Oil Pump 

Slide Valve 

Axial Position 

Indicator 

FIGURE 5-4: HYDRAULIC INTERNALLY CHANGEABLE SLIDE VALVE 25% AXIAL POSITION - TYPICAL 

“N” VERSION 

PAGE 5 - 6 3/02


TABLE 5-2: HYDRAULICALLY CONTROLLED SLIDE VALVE - APPROXIMATE WEIGHTS 

MODEL 

Compressors with Individual Cover Plates 

If your compressor design does not have a single suction-end cover do not pull the dowel 

pin, prior to disassembly. The slide valve cylinder with slide valve is removed using the jack 

bolting provided. Slinging parts to an overhead crane may be useful to assist removal. 

Remove control cylinder o-ring and discard. 

Replacement 

SLIDE VALVE ONLY 

(INTERNALLY 

CHANGEABLE) 

SLIDE VALVE & 

CONTROL POSITIONER 

CYLINDER 

With the slide valve at the 80% axial position, hold positioner piston rod with a strap wrench 

to prevent shearing the positioning dowel and remove the slide valve nut and lockwasher. 

Remove slide valve from the piston rod. Clean parts, being careful to remove Loctite residue 

from piston rod and nut threads. 

Select a new slide valve with the proper volume ratio (V i) required. Reassemble slide valve 

to piston rod with locating dowel properly aligned with the slide valve groove. Apply Loctite 

222 (purple) to the first two piston rod threads and install lockwasher and nut. Hold the piston 

rod with a strap wrench and tighten nut to the proper torque value in Table 1-4 on Page 

5-10. Install a new o-ring lubricated with a high viscosity silicone fluid such as Parker Super- 

O-Lube or equal. Remove jack bolts. 

Slide Valve Cylinder Reassembly Into Compressor 

SUCTION COVER WITH 

CYLINDER & SLIDE 

VALVE 

LB (kg) LB (kg) LB (kg) 

AR166 24 (11) 105 (48) 195 (89) 

AR208 46 (21) 175 (80) 310 (141) 

AR260K 75 (34) 230 (105) 420 (191) 

AR260 85 (39) 260 (118) 525 (239) 

Insert slide valve cylinder with attached slide valve into the compressor being careful to level 

the assembly and lift to put the slide valve on slide guide. On compressors with individual 

cover plate (“N”), reinstall the cylinder onto the dowel. Tighten capscrews to the proper 

torque in Table 1-3 on page 1-10. Remove lifting tool as required and replace thread protection 

plugs or grease. 

Reattach oil lines, thrust balance line and slide valve axial position indicator as required. 

Stamp or vibra-etch the new volume ratio (V i) and date on the volume ratio change plate. 

See Figure 1-7: on page 1-8, top view for plate location. 

3/02 PAGE 5 - 7


Using the pre-lube pump, move the slide valve to the 0% position. Check the yellow visual 

position pointer for 0% indication. Calibrate if necessary. 

NOTE: THE YELLOW POSITION POINTER IS A SLIDING FRICTION FIT ON THE INDI- 

CATOR SHAFT, TO ALLOW FOR CALIBRATION. 

Yellow Position Pointer 

Front View - Case Cover Removed 

Mounting Bolt 

Cover 

Bolt 

Double 

Cam 

Precision Potentiometer 

Cross Section - Cover in Place 

Do Not Use a Mounting Gasket between Case and Cylinder Cover 

FIGURE 5-5: SLIDE VALVE AXIAL POSITION INDICATOR TRANSDUCER 

Slide Valve Axial Position Indicator Transducer 

Single Cam 

M16 or 3/8 “ NPT 

The slide valve axial position indicator transducer provides a visual indication dial (0 to 

100%), 5 limit switches with adjustable cams and a precision potentiometer for monitoring 

the axial position of the slide valve. Switches 1 and 2 (pins 10 and 9) are single cam and calibrated 

by Ariel to represent the 0 and 100% positions. Switches 3 thru 5 are provided so 

that up to five additional slide valve positions can be calibrated and monitored electronically. 

The position indicator transducer is also equipped with a precision wire wound potentiometer 

to monitor slide valve position. To calibrate the limit switch cams, use the adjustment 

wrench provided inside the position transducer indicator case and held in place with a thumb 

screw. 

The visual position indicator (yellow pointer) is calibrated by rotating it about a shaft. Its position 

is held by friction from tightening a set screw and is pre-positioned by Ariel during 

assembly. If the pointer indicates more than 100% at full load or less than minimum at startup, 

then it must be readjusted. 

PAGE 5 - 8 3/02


If the potentiometer or cams are used to electronically stop slide valve travel, calibration is 

very important at minimum and maximum travel. The last few percent of travel to the full load 

position have a dramatic affect upon compressor flow and horsepower. 

10 

FIGURE 5-6: SLIDE VALVE AXIAL POSITION INDICATOR TRANSDUCER - WIRING DIAGRAM 

1 kS 

1 

1 

Cams 

------ Factory Set ------ 

0% 100% 

9 

2 

1 

8 

Cams 

------------ Adjustable by User --------------- 

2 2 2 2 2 

1 

3 

FIGURE 5-7: POSITION INDICATOR - PRECISION WIRE-WOUND POTENTIOMETER 

3/02 PAGE 5 - 9 

7 

4 

1 

Electrical Connections 

6 

1 

5 

5 

4 

Precision 

Potentiometer 

3 

3 

R 

1 

1 

2 

2 

CW


Hole for Thumbscrew to 

Secure Wrench Inside of Case 

Cam Adjustment Wrench - 

Ariel Part Number 000550 

FIGURE 5-8: POSITION INDICATOR TRANSDUCER - CAM ADJUSTMENT 

TABLE 5-3: POSITION INDICATOR - PRECISION WIRE-WOUND SINGLE TURN POTENTIOMETER 

TECHNICAL DATA 

kS 

kS 

344S 

S 

Nominal Resistance 1 (0° TO 330°) 

Resistance Tolerance + 5% 

Resolution 0.079% 

Power Rating 5 W / 40°C 

Maximum Wiper Current in Malfunction 100 mA 

Protection IP 50 

Full Load Position (Maximum Position) 100% = 330° = 1 

Starting Position (Minimum Position - Externally Changeable) 20% = 114° = 

Starting Position (Minimum Position - Internally Changeable) 0% = 60° = 180 

Externally Changeable Slide Valve 

Reverse Wrench to 

Adjust Opposite Side 

Double 

Cam 

Single 

Cam 

Slide Valve Volume Ratio (V i ) Change - Externally Changeable V i 

The slide valve external spacer may be changed or eliminated to adjust for a different volume 

ratio (V i) that is appropriate for current operating conditions. Refer to Table 5-4 on Page 

5-11 for spacer thickness values. 

PAGE 5 - 10 3/02


TABLE 5-4: SPACER THICKNESS - EXTERNALLY CHANGEABLE V i Slide Valve 

COMPRESSOR 

MODEL 

SPACER THICKNESS FOR ADJUSTING VOLUME RATIO (V i ) 

4.8 V i 3.5 V i 2.6 V i 2.2 V i 

INCHES (cm) INCHES (cm) INCHES (cm) INCHES (cm) 

AR166 

0.802 (2.04) 1.812 (4.60) 2.544 (6.46) 

AR208 No Spacer Required 1.000 (2.54) 2.270 (5.77) 3.190 (8.10) 

AR260K for 4.8 Vi 0.972 (2.47) 2.150 (5.46) 3.000 (7.62) 

AR260 1.260 (3.20) 2.840 (7.21) 3.907 (9.92) 

Crank 

Handle 

Hand 

Wheel 

Balance Oil 

Connection 


Plug 

Balance 

Piston 

Cylinder 

Mounting 

Bolts 

Balance 

Cylinder 

Vi 

Spacer 

Locating 

Dowel 


Plug 

Lockwasher 

& Nut 

FIGURE 5-9: HAND WHEEL EXTERNALLY CHANGEABLE SLIDE VALVE 100% POSITION - TYPICAL 

Axial Positioner Hydraulic Oil 

Indicator Connection 


Plug 

Positioner 

Piston 

Cylinder 

Mounting 

Bolts 

Hydraulic 

Cylinder 

Vi 

Spacer 


Plug 

Locating 

Dowel 

FIGURE 5-10: HYDRAULIC EXTERNALLY CHANGEABLE SLIDE VALVE 100% POSITION - TYPICAL 

3/02 PAGE 5 - 11 

Slide 

Valve 

Slide 

Valve 

Lockwasher 

& Nut 

20% Position 

Stop 

20% Position 

Stop


V i Spacer Adjustments - Externally Changeable V i 

The slide valve volume ratio (V i ) can be varied, by changing or eliminating the spacer, bolts 

and dowel pin, with the compressor stopped and depressurized. Determine the Vi required 

and secure the appropriate items from the toolbox or rebuild kit components, including 

spacer, mounting bolts, dowel pin, o-ring, along with required hand tools. 

To replace the V i spacer, be sure the compressor is properly vented and that the equipment 

is locked out so rotors can not turn. On hand wheel controlled units, remove oil balance tubing 

and drain plug to bleed cylinder oil that restricts axial piston movement. On hydraulically 

controlled units, open oil control valves and drain plug to bleed cylinder oil, if oil lines and 

electrical conduit lines are not flexible they will have to be removed. Remove locating dowel 

pin from cylinder mounting flange using threaded 10mm slide hammer adapter. Insert Ariel 

supplied jackbolts, which supports V i spacer, then loosen and remove cylinder mounting 

bolts. Remove V i spacer by moving cylinder axially with jackbolts, and backing them off. 

Clean cylinder and compressor mating flanges and coat with Never Seez. Install or omit the 

proper spacer to achieve the required V i; support spacer and adjust opening space with jack 

bolts. Install correct length mounting bolts and locate cylinder to compressor by installing 

appropriate length dowel pin. Tighten capscrews to the proper torque value as shown in 

Table 1-4 on page 1-10. Remove jacking bolts and lifting tools as required and replace 

thread protection plugs or grease. 

Reattach or re-tube oil lines and/or conduit, and re-install drain plugs as required. 

Stamp or vibra-etch the new volume ratio (V i ) and date on the volume ratio change plate. 

See Figure 1-7: on page 1-8 for plate location. 

Move the slide valve through its entire range of travel. See Table 1-2 on page 1-7 for hand 

wheel controlled slide valve travel distance details. 

Slide Valve Inspection/Replacement - Externally Changeable 

V i 

The slide valve may be removed for inspection, but its removal is not required to change the 

volume ratio (V i ). If the slide valve volume ratio (V i ) is also to be adjusted by changing or 

eliminating the spacer, see “Vi Spacer Adjustments - Externally Changeable V i” above for 

details. 

Removal 

To remove the slide valve, position the slide valve to the 100% axial position. The male rotor 

must be rotated so that the shaft keyway is at the top (12 o’clock position), which positions 

rotor mesh for ease of slide valve cylinder removal and installation. Be sure the compressor 

is properly vented and that the equipment is locked out so rotors can not turn. Remove the 

oil line(s) and/or drain plug from the slide valve cylinder, and remove rotor housing drain 

plug to drain residual oil. Replace drain plugs when oil stops running. For hydraulically con- 

PAGE 5 - 12 3/02


trolled units, also unbolt slide valve indicator or remove electrical connection, as required, to 

allow for slide valve cylinder removal. 

The slide valve cylinder is precision located to the compressor housing using a dowel pin. 

Without removing the dowel pin, insert jack screws to support the V i spacer, if there is one 

and remove cylinder mounting bolts (capscrews). The control cylinder with the slide valve is 

removed using the jack bolts provided. Slinging parts to an overhead crane may be useful to 

assist removal. See Table 5-5 and Table 5-6 for approximate weights of components. 

Remove control cylinder o-ring and discard. 

Inspect slide valve and replace as required. 

Replacement 

With the slide valve at an 80% axial position, hold piston rod with a strap wrench to prevent 

shearing the positioning dowel and remove slide valve nut and lockwasher. Remove slide 

valve from the piston rod. Clean parts, being careful to remove Loctite residue from piston 

rod and nut threads. 

Reassemble slide valve to piston rod with locating dowel properly aligned with the slide 

valve groove. Apply Loctite 222 (purple) to the first two piston rod threads and install lockwasher 

and nut. Hold the piston rod with a strap wrench and tighten nut to the proper torque 

value in Table 1-4 on page 1-10. Install new o-ring lubricated with a high viscosity silicone 

fluid such as Parker Super-O-Lube or equal. 

Slide Valve Cylinder Assembly Into Compressor 

Insert slide valve cylinder with attached slide valve into the compressor, being careful to 

level the assembly while lifting piston rod/slide valve to put the slide valve on slide guide. 

With the V i spacer supported on the jack bolts when applicable, reinstall the cylinder flange 

onto the dowel. Insert and tighten capscrews to the proper torque in Table 1-4 on page 1-10. 

Remove jack bolts and lifting tools as required; replace thread protection plugs or grease. 

Reattach oil line(s), drain plug(s) and position indicator as required. 

Move the slide valve through its entire range of travel. See Table 1-2 on page 1-7 for hand 

wheel controlled slide valve travel distance details. 

TABLE 5-5: HAND WHEEL CYLINDER CONTROLLED SLIDE VALVE - APPROXIMATE WEIGHTS 

MODEL 

SLIDE VALVE ONLY (EXTERNALLY 

CHANGEABLE) 

SLIDE VALVE, HAND WHEEL & 

CYLINDER 


AR166 19 (8.6) 80 (36) 

AR208 40 (18) 160 (73) 

AR260K 72 (33) 220 (100) 

AR260 82 (37) 250 (114) 

3/02 PAGE 5 - 13


TABLE 5-6: HYDRAULICALLY CONTROLLED SLIDE VALVE - APPROXIMATE WEIGHTS 

MODEL 

Oil Pump and Geared Tooth Coupling 

Oil Pump Replacement 

SLIDE VALVE ONLY 

(EXTERNALLY CHANGEABLE) 

SLIDE VALVE & CONTROL 

POSITIONER CYLINDER 


AR166 19 (8.6) 75 (34) 

AR208 40 (18) 155 (70) 

AR260K 72 (33) 215 (98) 

AR260 82 (37) 245 (111) 

To replace the oil pump, first mark the pump suction and discharge end connections, then 

remove oil piping from the pump as required. To remove pump from compressor, remove 

capscrews (or stud-nuts) and slide pump out, separating the coupling halves at the sleeve. 

The coupling driven-half will come out attached to the pump shaft, while the coupling sleeve 

is retained by the drive half of the coupling which is bolted and dowelled to the female rotor. 

Remove o-ring and discard. 

NOTE: ON THE AR166, WHERE THE ADAPTER COVER PLATE DOES NOT HAVE ITS 

OWN BOLTING (i.e. HELD IN PLACE BY THE PUMP BOLTING), REMOVE THE 

ADAPTER AND DISCARD O-RING. 

Adapter cover plates which have separate bolting need not be removed. Loosen the key set 

screw and remove gear coupling-half from the pump shaft with a two or three jaw gear 

puller. Inspect the coupling’s geared teeth, if there is excessive wear, replace the entire coupling 

with a new assembly. 

Replace the pump with a new part, correct for the compressor application. Install the coupling 

driven-half to the new pump shaft with key installed and firmly seated. There should be 

a slight clearance of 0.005 in. (0.13mm) between the top of the key and the mating coupling. 

Position the coupling-half on the pump shaft end so the axial spacing between the coupling 

halves is 3/32 in. (2.5mm), then tighten set screw, see Figure 5-11: on Page 5-15. 

NOTE: FOR THE AR166 & AR260 THE COUPLING DRIVEN-HALF SHOULD BE 

APPROXIMATELY FLUSH WITH THE PUMP SHAFT END. FOR THE AR208, 

THE COUPLING DRIVEN HALF EXTENDS BEYOND THE SHAFT END BY 

ABOUT 13/32 IN. (10mm). 

Replace o-ring(s) with new parts. Lubricate adapter cover plate bore and coupling sleeve 

teeth with clean oil. Slide the pump into place, with shaft position rotated to properly engage 

gear teeth. Be sure pump flow is in the correct direction. Replace fasteners and tighten to 

the proper torque shown in Table 1-4 on page 1-10. Pour a small quantity of oil into pump 

intake and re-attach oil piping as required. 

PAGE 5 - 14 3/02


Coupling Replacement 

To replace the entire pump coupling, begin as described in first paragraph under Oil Pump 

Replacement above. Remove the fasteners as required, adapter cover plate and o-ring. Discard 

the o-ring. Remove the drive coupling-half socket head cap screw. Remove the drive 

coupling-half and sleeve assembly, being careful not to cock the coupling half and break the 

hardened dowel pins. Replace coupling drive half and sleeve with new parts. Position coupling 

drive-half, with sleeve installed, over dowel pins and draw up by tightening the cap 

screw to the proper torque shown in Table 1-3 on page 1-10. Verify the sleeve is free to pivot 

on the drive coupling-half gear teeth. Lubricate rotor housing bore with clean oil and install 

adapter cover plate, with a new o-ring. Replace fasteners and tighten to proper torque 

shown in Table 1-4 on page 1-10. Position new coupling driven-half on the end of the pump 

shaft and proceed with oil pump re-installation in “Oil Pump Replacement” above. 

Approximately 

13/32” (10mm) 

AR208 Only 


Pump 

Fasteners 

Set Screw & 

Key 

O-Ring 

B 

Coupling 

Driven Half 

Cover Plate - 

Adapter 

“A” - “B” = 3/32 in. (2.5mm) 

Coupling 

Sleeve 

FIGURE 5-11: OIL PUMP AND COUPLING - TYPICAL 

3/02 PAGE 5 - 15 

A 

Dowel 

Male 

Rotor 

Coupling 

Drive Half 

Socket Head 

Capscrew 

Female 

Rotor


Ethylene Glycol Contamination 

Ethylene glycol contamination of a compressor can result from a water-cooled oil cooler 

leak. 

Ethylene glycol anti-freeze coolant mixture leaking into the oil can cause bearing damage 

and rotor seizure due to lack of adequate lubrication. The oil should be changed as recommended 

in Section 6, while being routinely sampled and analyzed by a qualified laboratory 

to verify suitability for continued use, including checking for ethylene glycol contamination. 

If contamination is found, find and fix coolant leak. Even small quantities of ethylene glycol in 

the oil can be detrimental. If contamination is less than 5%, drain oil, replace filters and flush 

oil system, including all piping, with a 50-50 mixture of butoxyethanol (Dow Chemical Co. 

Dowanol EB or equal) and 10W oil using a motor driven pump. Flushing should be done on 

a warm compressor. Bearings should be continuously flushed for 1/2 hour while barring over 

compressor. All surfaces that come in contact with the oil are to be flushed which includes 

spraying all interior surfaces in the compressor and gas/oil separator/coalescing filter. Completely 

drain cleaning mixture, being sure to drain all components of the oil system. Repeat 

flushing operating using a 60/40 mixture of 10W oil and kerosene or fuel oil. Completely 

drain oil system, install new filters and fill with proper oil. 

If sampling indicates that glycol contamination is greater than 5% or compressor has seized 

due to contamination, the unit is to be returned to Ariel, torn down, cleaned with 100% butoxyethanol, 

flushed with kerosene or fuel oil and repaired as required. All surfaces that come 

in contact with oil must be cleaned with butoxyethanol, including all passages and piping, 

and then flushed with kerosene or fuel oil. Oil and filters must be changed. Coolant leak is to 

be found and repaired. 

Butoxyethanol presents health and safety hazards. Use proper eye and skin protection and 

adequate ventilation. Do not use near open flame or sparks. See manufacturer's Material 

Safety Data Sheet for complete details. 

Ethylene glycol, butoxyethanol, contaminated oils and solvents must be properly disposed. 

A chemical disposal service should be used. 

�� 

�� 

�� 

Mineral deposit build-up can occur when liquids have not been completely removed from the 

gas stream, particularly in low pressure natural gas applications. These minerals (such as 

salt and calcium dissolved in water saturated process gas) plate out when water flashes off 

due to pressure drop or heat. The minerals can build up on the suction strainer screen and 

in the compressor. If mineral build-up is observed during maintenance, additional steps 

should be taken for liquid removal from the gas stream prior to entering the compressor. 

PAGE 5 - 16 3/02


SECTION 6 - TECHNICAL ASSISTANCE 

Recommended Maintenance Intervals 

Like all equipment, Ariel compressors do require maintenance. The frequency of maintenance 

is dictated by the environment in which the compressor is placed, the loads the user 

imposes on the compressor and the cleanliness of the gas. 

First and foremost on the preventative maintenance list is the completion and compliance 

with the Ariel Corporation Packagers Standard and Compressor Start Up Check List. All 

items must be adhered to, both before and after start up. 

The following is a guide only and, as stated above, may vary due to operating conditions. 

The time intervals start with the start up date of the unit. If your oil supplier's recommend oil 

service changes are more frequent than the Ariel recommendations, the supplier’s intervals 

should be followed. Regular oil analysis is recommended. If problems develop the oil should 

be changed immediately and the cause of the problem determined and corrected. 

A log book should be kept with each unit. Every maintenance item can be entered with 

exacting detail in order that records will be available for tracking maintenance costs per unit 

and for trouble-shooting. 

Operator logs should be reviewed by qualified personnel to determine trends in compressor 

performance and/or maintenance. 

Daily 

1. Check oil pressures and temperature. Recommended compressor inlet oil temperature 

is 150°F (65°C). 

2. Check gas/oil separator oil level when compressor is in operation. It should be in 

mid-sight glass and, if not, determine and correct cause. Do not overfill. 

3. Check seal vent for blowing or excessive leakage. If blowing or leaking, determine 

cause and, if necessary, replace mechanical seal parts. 

4. Check and correct any gas leaks. 

5. Check and correct any oil leaks. 

6. Check operating pressure and temperatures. If not normal, determine cause of 

abnormality. It is recommended that a daily log of operating temperatures and 

pressure be kept for reference. See typical log sheet on page 3-6. 

7. Check shutdown set points. High-low pressure shutdowns set as close as practical 

to current operating conditions. 

8. Check for unusual noises or vibrations. 

9. Check gas/oil separator scavenged oil flow indicator for oil and entrained gas 

flow. Adjust as required. 

3/02 PAGE 6 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 6 - TECHNICAL ASSISTANCE 

10. Check oil filters differential pressures. 

11. Check slide valve position. Adjust as required. 

12. Check counter thrust gas balance pressure. Adjust as required. 

13. Check gas suction strainer differential pressure. 

Monthly (in addition to Daily Requirements) 

1. Check and confirm safety shutdown functions. 

2. Adjust counter-thrust gas balance pressure for current operating conditions. 

3. Review oil analysis to determine if good for continued use. 

4. Inspect anchor bolts and shims for looseness. Tighten as required. 

Every 6 Months or 4,000 Hours (plus Daily/Monthly) 

1. Check oil viscosity requirements for current gas analysis and operating conditions. 

2. Change oil filters or before differential pressure exceeds collapse pressure, or 

as specified by the manufacturer or oil consultant. 

3. Verify that oil is suitable for continued use. A more frequent oil change interval 

may be required if operating in an extremely dirty environment or if the oil supplier 

recommends it or if an oil analysis dictates it. A less frequent oil change 

interval may be required If the oil is replenished on a regular basis due to usage. 

4. Clean strainers - oil and gas. 

5. Re-tighten hold down stud-nuts to proper torque values and perform a soft foot 

check. More than 0.002 inch (0.05 mm) pull down requires re-shimming. 

6. Inspect coupling discs for cracking and/or axial distortion. Realign if necessary 

to hold coupling alignment within 0.002 inches (0.05 mm) TIR. 

Yearly or every 8,000 Hours (plus Daily/Monthly/6 Months) 

1. Inspect compressor mounting for twist or bending by checking shimming of compressor 

feet. 

2. Check and re-calibrate all temperature and pressure gauges. 

3. Change gas/oil separator filter element or before differential pressure exceeds 

collapse pressure, or as specified by the manufacturer or oil consultant. 

Trouble Shooting 

Minor problems can be expected during the routine operation of an Ariel compressor. These 

troubles are most often traced to liquid, dirt, improper alignment adjustment or to operating 

personnel being unfamiliar with Ariel compressors. Difficulties of this type can usually be 

corrected by cleaning, proper alignment adjustment, elimination of an adverse condition, 

replacement of a relatively minor part or proper training of the operating personnel. 

PAGE 6 - 2 3/02


Major problems can usually be traced to long periods of operation with unsuitable lubrication, 

improper counter-thrust gas balance pressure, careless operation, lack of routine maintenance 

or the use of the compressor for purposes for which it was not intended. 

Recording of the pressures and temperatures is valuable because any variation, when operating 

at a given load point, indicates trouble. 

While it would be impossible to compile a complete list of every possible problem, listed 

below are some of the more common ones with their possible causes. 

Low Oil Pressure 

High Oil Pressure 

Problem Possible Causes 

Low Oil Temperature 

High Oil Temperature 

High Gas Discharge 

Temperature 

Excessive Vibration and/or 

Noise in Compressor 

Driven coupling-half loose on pump shaft (coupling disengaged). 

Defective pressure gauge. 

Oil regulating valves improperly adjusted for conditions. 

Dirty or plugged oil strainer. 

Dirty oil filter. 

Improper low oil pressure switch setting. 

Low oil viscosity. 

Excessive leakage at seals or bearings. 

Leaking oil pump check valve. 

Oil pump wear. 

Improper end clearance in oil pump. 

Cold oil. 

Oil regulating valves improperly adjusted for conditions. 

High oil viscosity. 

Oil temperature too low. 

Thermostatic valve element defective. 

Oil heater or thermostat defective. 

Thermostatic valve element defective. 

Cooler fan not working. 

Oil cooler dirty. 

Low oil viscosity. 

Inadequate rotor injection oil rate. 

Plugged oil strainer. 

High oil temperature 

High suction temperature. 

High suction or discharge pressure. 

Loose compressor hold down bolting. 

Coupling not properly aligned. 

Improper lube oil and/or insufficient lube rate. 

Lubrication failure. 

Liquids in gas. 

Excessive rotor end play. 

Loose or worn bearings. 

3/02 PAGE 6 - 3


Problem Possible Causes 

High Oil Consumption 

Oil Leakage at Slide Valve 

Axial Position Indicator Case 

Mounting 

Excessive Leakage at 

Mechanical Seal Weep Tube 

Axial Position Indicator Off at 

0% (unloaded) and 100% (full 

load) positions 

Compressor Flow Does Not 

Match Performance Prediction 

at Full Load 

Oil system over filled. 

Separator-scavenged oil line plugged or throttling valve closed. 

Excessive oil dilution from process gas. 

Collapsed coalescing filter element. 

Oil/ gas separator coalescing filter gaskets not sealed or defective. 

Improper coalescing filter element installed. 

Position indicator drive rod seal damaged. Contact Ariel for replacement. 

Mechanical seal is not effective and should be replaced. 

Yellow pointer friction loose; adjust pointer and tighten set screw. 

Indicator case shaft improperly re-installed on the slide valve indicator rod 

or shaft coupling setscrews inside of case are loose; remove case, position 

the slide valve and yellow pointer to the minimum unloaded position (0% 

internally changeable or 20% externally changeable cylinders) and reinstall. 

If coupling is loose, contact your packager or Ariel. 

Verify that the V i used in calculations matches the V i installed in compressor. 

The axial position indicator may be improperly adjusted. 

Slide valve not at 100% position; adjust or calibrate yellow pointer, cams or 

potentiometer as required. 

Performance calculation input data incorrect; verify accurate gas analysis, 

rotating speed, suction pressure or temperature readings used. Performance 

prediction is based upon compressor suction and discharge flange 

conditions. 

Verify any compressor bypass valve(s) fully closed and not leaking. 

Verify suction gas strainer clean and intact. 

PAGE 6 - 4 3/02


SECTION 7 - APPENDICES 

Ariel Tools 

Ariel Furnished Tools 

Ariel provides one tool box with each unit with customized tools included in the box as listed 

below (see Figure 7-1: and Figure 7-2: and Figure 7-3:). 

TABLE 7-1: ARIEL FURNISHED TOOLS 

TOOL DESCRIPTION 

PART NUMBER OR SIZE 

QTY AR166 AR208 AR260K, AR260 

Toolbox 1 A-0798 

Spanner Wrench - Mechanical Seal Locknut 1 000531 000512 000012 

Jack Bolt (12 Point Capscrew) - Removing 

Mechanical Seal Housing, class 12.9 

2 M12x1.75x40mm 

M16x2 

x50mm 

M16x2 

x50mm 

Mechanical Seal Installation Tool 1 000608 000652 000653 

Cam Adjusting Wrench - (Hydraulic Only) Slide 

Valve Axial Position Indicator Transducer 

1 

000550 

Allen Wrench - Axial Position Indicator Bolts 1 4mm 

Forged Steel Eye Bolt - Lifting Compressor a 

2 

3/4”-10x 

2 

3/4”-10x 

2 

3/4”-10x 

2 

Jack Bolt (12 Point Capscrew) - Removing 

Slide Valve Control Cylinder, class 12.9 

2 M12x1.75x60mm M12x1.75x60mm 

M16x2x 

80mm 

Socket Head Capscrew - Replacement Bolt for 

Axial Position Indicator, class 12.9 

1 

M5 x 0.8 x 35mm 

Bolting - Tightening Torque Charts 1 D-2159 

Spacers for Externally Changeable Slide Valve 

Only (with cylinder mounting bolts, dowel pin, 

label and label screws for each Vi setting) 

1 

each 

3.5 Vi , 2.6 Vi & 2.2 V b 

i 

See Figure 7-2: 

a. See Table 1-1 on page 1-5 for compressor weights; and Figure 1-7: on page 1-8 for lifting location connections. 

b. One spacer may be installed in compressor as ordered. The Vi ratio is stamped on each shim-spacer. For 4.8 Vi, the 

spacer is omitted. See Table 5-4 on page 5-11 for spacer thicknesses vs. compressor model and Vi. Ariel provides these tools at no additional charge. Please contact your Distributor if you do 

not have these tools. 

These tools are specifically designed for use on Ariel units. Clean all tools before use. 

Ensure that the tool and the part being removed or installed are fully engaged during the 

process. If a tool is missing, worn or broken, please call your distributor for a replacement. 

Do not use substitute, worn or broken tools. 

3/02 PAGE 7 - 1

FOR MODELS: AR-166, AR-208, AR-260K & AR-260 SECTION 7 - APPENDICES 

FIGURE 7-1: SPANNER WRENCH FOR MECHANICAL SEAL LOCKNUT - TYPICAL 

FIGURE 7-2: V i SPACER FOR EXTERNALLY CHANGEABLE SLIDE VALVE ONLY - TYPICAL 

FIGURE 7-3: MECHANICAL SEAL CARTRIDGE INSTALLATION TOOL 

PAGE 7 - 2 3/02


Minimum Hand Tools Required 

The following hand tools are normally all that is required to work on Ariel compressors. 

These are in addition to the Ariel furnished tools listed in Table 7-1. Please contact Ariel if 

you have questions about tools on Ariel units. 

1/2" Square Drive Ratchet Wrench 

• 

2" and 6" Extensions for above Ratchet 

• 

1/2" Square Drive Breaker Bar 

• 

1/2" Drive Speed Wrench 

• 

• 1/2" Female x 3/4" Male Adaptors 

• 1/2" Square Drive Universal Joint 

• 3/8" Square Drive Torque Wrenches (10 LB-IN to 250 LB-IN) 

• 1/2" Square Drive Torque Wrenches (15 LB-FT to 250 LB-FT) 

• 3/4" Square Drive Torque Wrench (to 1590 LB-FT) 

• 7/16", 1/2", 9/16", 3/4", and 15/16" Sockets for a 1/2" Square Drive Ratchet Wrench 

• 1/2" Hex Key and 1/4" Hex Key (Allen) Sockets for a Square Drive Ratchet Wrench 

• 5/16" - 12 Point Box Wrench 

1/2" x 9/16" Open End Wrench 

• 


• 


• 

2 - Medium Size Screw Drivers 

• 

• Slugging Hammer 

• Set of 3/8" Drive, 12 Point Sockets 

• Set of Inch 1/2" Drive, 12 Point Sockets 

• Set of Metric 1/2" Drive, 12 Point Sockets 

• 3/8" Square Drive Ratchet Wrench 

• 7/8", 1", 1-1/8", 1-3/8", M20, M24 and M27, 3/4" Drive, 12 Point Sockets 

• 1-5/16" and 1-1/2", 3/4" Drive, Sockets 

• 3/4" Square Drive Ratchet Wrench 

• 3/4" Female to 1" Male Adaptor 

• Strap Wrench 

• Slide Hammer (to remove dowel pins) 

3/02 PAGE 7 - 3


Terms, Abbreviations 1 and Conversion to SI Metric 2 

Area 

in 2 or square inch x 0.00064516 = meter 2 , or m 2 

in 2 or square inch x 6.4516 = centimeter 2 , or cm 2 

Flow - Gas 3 

MMSCFD or million standard cubic feet per day x 0.310 = normal meter 3 /second, or m 3 /s n 

SCFM or standard cubic feet per minute x 1.607 = normal meter 3 /hour, or m 3 /h n 

Flow - Liquid 

GPM or US gallons per minute x 0.0630902 = liter/second, or L/s = dm 3 /s 

GPM or US gallons per minute x 0.227125 = meter 3 /hour, or m 3 /h 

Force 

lbf or pound (force) x 4.44822 = Newton, or N 

Heat 

BTU or British Thermal Units x 1.05506 = kilojoule, or kJ 

Length 

in. or " or inches x 25.4000 = millimeters, or mm 

ft. or feet x 0.304800 = meter, or m 

Mass 

lb. or pound (mass) x 0.453592 = kilogram, or kg 

1. US units of measure can appear abbreviated in upper or lower case. 

2. Maintain upper and lower case letters in SI Metric as shown. 

3. US standard is based on 14.696 psia & 60°F; Metric normal is based on 1.01325 bar & 0°C. 

PAGE 7 - 4 3/02


Moment or Torque 

LB x FT or pound-foot (force) x 1.35583 = Newton-meter, or N . m 

LB x IN or pound-inch (force) x 0.112985 = Newton-meter, or N . m 

Power 1 

HP or Horsepower x 0.745700 = kilowatt, or kW 

Pressure 2 or Stress 

PSI or Pounds per Square Inch x 6.89476 = kiloPascal, or kPa 

PSI or Pounds per Square Inch x 6894.76 = Pascal, or Pa 

PSI or Pounds per Square Inch x 0.0689476 = bar 

bar x 100 000 = Pascal, or Pa 

bar x 100 = kiloPascal, or kPa 

bar x 14.50377 = PSI, or Pounds per Square Inch 

Speed 

FPM or feet per minute x 0.005080 = meter per second, or m/s 

RPM or r/min or revolutions per minute ÷ 60 = revolutions per second, or rev/s 

Temperature 

°F or degrees Fahrenheit. (°F - 32)/1.8 = degrees Celsius, or °C 

Time 

sec = second, or s 

min or minute x 60 = second, or s 

hr. or h or hour x 3600 = second, or s 

1. Horsepower based on 550 ft-lb/sec 

2. G suffix PSIG (bar g ) indicates gauge pressure, PSIA (bar a ) indicates absolute and PSID (bar d ) indicates differential. 

3/02 PAGE 7 - 5


Viscosity 

SSU, SUS or Sailboat Universal seconds x 0.22 - (180/SSU) = mm 2 /s = scientist, or cSt 

(for a range of 33 thru 200,000 SUS) 

Volume 

gal or gallons (US liquid) x 3.78541 = liter, or L 

Other Abbreviations 

S = Ohm = V/A = Volt ÷ Ampere = Electrical Resistance 

A = Ampere = Electrical Current 

ANSI = American National Standards Institute 

bar a = Absolute Pressure 

bar d = Differential Pressure 

bar g = Gauge Pressure 

CI = Cast Iron 

CL. = Clearance 

CU = Cubic 

CW = Clockwise 

CCW = Counter Clockwise 

6 = Centering 

DIN = German Standards Institute 

INJ = Injection 

k = Ratio of Specific Heats 

k = kilo, see Table 7-3 

L/D Ratio = Length of male rotor divided by its diameter 

MAX. = Maximum 

MIN. = Minimum 

N/A = Not Applicable 

NO. = Number 

NPT = National Pipe Thread 

P d = Discharge Pressure 

PAGE 7 - 6 3/02


P s = Suction Pressure 

% = Percent 

QTY = Quantity 

SG = Specific Gravity 

SI = International System, as applied to the modern metric system 

S. N. or S/N = Serial Number 

THD = Thread 

TIR = Total Indicator Reading 

TPI = Threads per Inch 

UNC = Unified (Inch) National Coarse Screw Threads 

UNF = Unified (Inch) National Fine Screw Threads 

V i = Volume Ratio = Volume of gas, in actual volume, at point where compression begins, 

divided by volume of gas, in actual volume, at end of compression ( = 

----- ) 

V = Volts = Electrical Potential 

W = Watt = Power 

W/ = With 

3/02 PAGE 7 - 7 

V i 

Vs Vd


Gas Analysis Common Abbreviations 

TABLE 7-2: GAS ANALYSIS COMMON ABBREVIATIONS 

COMMON ABBREVIATION 

COMPONENT NAME 

(SYNONYM) 

CHEMICAL 

FORMULA 

C1 Methane CH4 

C2 Ethane C2H6 

C3 Propane C3H8 

IC4 Iso-Butane (2-Methyl Propane) C4H10 

NC4 N-Butane C4H10 

IC5 Iso-Pentane (2-Methyl Butane) C5H12 

NC5 N-Pentane C5H12 

NEOC5 Neopentane C5H12 

NC6 Hexane C6H14 

NC7 Heptane C7H16 

NC8 Octane C8H18 

NC9 Nonane C9H20 

NC10 N-Decane C10H22 

NC11 N-Undecane (Hendecane) C11H24 

NC12 N-Dodecane C12H26 

C2- Ethylene (Ethene) C2H4 

C3- Propene (Propylene) C3H6 

BENZ Benzene C6H6 

TOL Toluene C7H8 

EBNZ Ethylbenzene C8H10 

CO Carbon Monoxide CO 

CO2 Carbon Dioxide CO2 

H2S Hydrogen Sulfide H2S 

H2 Hydrogen H2 

O2 Oxygen O2 

N2 Nitrogen N2 

H20 Water H20 

He Helium He 

Ar Argon Ar 

--- Air --- 

PAGE 7 - 8 3/02


Metric Factors 

TABLE 7-3: USEFUL SI METRIC MULTIPLE AND SUBMULTIPLE FACTORS 

Technical and Service Schools on Ariel Compressors 

Ariel schedules several in plant schools each year, which include classroom and hands on 

training. Ariel can also arrange to send a representative to provide a customized training 

school at your location. Contact Ariel for details. 

Ariel Customer Technical Bulletins (Formerly Ariel Newsletters) 

Ariel Customer Technical Bulletins provide important technical information including 

changes, corrections and/or additions to the Technical Manual for Packagers and End 

Users. Be sure to refer to this material before operating or servicing the equipment. 

A complete listing of these Bulletins is available at the Ariel Website, and copies may be 

obtained from the Packager or from Ariel. 

Vendor Literature 

MULTIPLICATION FACTOR PREFIX SI SYMBOL a 

1 000 000= 10 6 mega M 

1 000 = 10 3 kilo k 

100 = 102 hectob h 

10 = 10 1 

deka b da 

.1 = 10-1 decib d 

.01 = 10-2 centib c 

.001 = 10 -3 milli m 

.000 001 = 10 -6 micro : 

a. Maintain upper and lower case letters as shown. 

b. Not Recommended, but occasionally used. 

When available, vendor literature on purchased parts used in Ariel Compressors is provided 

on the Ariel Website (www.arielcorp.com), or copies may be obtained from the Packager or 

from Ariel. 

3/02 PAGE 7 - 9


Ariel Contact Information 

�� 

�� 

�� 

Ariel Response Center (ARC) 888-397-7766 740-397-1060 arc@arielcorp.com 

Spare Parts (toll free USA & Canada) or 740-393-5054 spareparts@arielcorp.com 

Order Entry 

740-397-3602 (International) 

740-397-6450 --- 

Ariel World Headquarters 

Technical Field Service 

740-397-0311 740-397-3856 

info@arielcorp.com 

fieldservice@arielcorp.com 

Ariel Website: www. arielcorp.com 

Ariel Response Center Technicians or Switchboard Operators will answer telephones 

• 

during Ariel business hours, Eastern Time - USA or after hours by voice mail. 

The after Hours Telephone Emergency System works as follows: 

• 

1. Follow automated instructions to Field Service Emergency Technical Assistance 

or Spare Parts Emergency Service. 

2. Calls are answered by voice mail. 

3. Leave Message: caller’s name, telephone number, serial number of equipment 

in question (frame, cylinder, unloader) and brief description of emergency. 

4. Your voice message is routed to an on-call representative, who will respond as 

soon as possible. 

Users must order all parts through Authorized Distributors. 

• 

PAGE 7 - 10 3/02

Heavy Duty Oil Flooded Twin Screw Rotary ... - Ariel Corporation

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