Parker O-Ring Handbook.pdf

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Basic O-Ring Elastomers 2-26 means of approximating the low temperature capability of an elastomer compression seal. The low temperature sealing limit is generally about 8°C (15°F) below the TR-10 value. This is the formula that has been used, with a few exceptions, to establish the recommended low temperature limits for Parker Seal Group compounds shown in Figure 2-25 and the Fluid Compatibility Tables in Section VII. This is the lowest temperature normally recommended for static seals. In dynamic use, or in static applications with pulsing pressure, sealing may not be accomplished below the TR-10 temperature, or approximately 8°C (15°F) higher than the low-limit recommendation in the Parker Handbook. These recommendations are based on Parker tests. Some manufacturers use a less conservative method to arrive at low temperature recommendations, but similar compounds with the same TR-10 temperature would be expected to have the same actual low temperature limit regardless of catalog recommendations. A few degrees may sometimes be gained by increasing the squeeze on the O-ring section, while insuffi cient squeeze may cause O-ring leakage before the recommended low temperature limit is reached. The low temperature limit on an O-ring seal may be compromised if the seal is previously exposed to extra high temperature or a fl uid that causes it to take a set, or to a fl uid that causes the seal compound to shrink. Conversely, the limit may be lowered signifi cantly if the fl uid swells the compound. See Figure 2-26. Retraction % TR Test According to ASTM-D 1329/ISO S 2921 for a NBR 70 Shore A Compound 100 90 80 70 60 50 40 30 20 10 °C °F -60 -76 -50 -58 -40 -40 -30 -22 -20 -4 Temperature -10 -14 Test results: TR 10 = -31.5°C (-25°F) TR 50 = -24.0°C (-11°F) TR = -20.0°C (-4°F) 70 0 32 10 50 Figure 2-26: TR Test According to ASTM-D 1329/ISO S2921 for a NBR 70 Shore A Compound Parker O-Ring Handbook 20 68 With decreasing temperature, elastomers shrink approximately ten times as much as surrounding metal parts. In a rod type assembly, whether static or dynamic, this effect causes the sealing element to hug the rod more fi rmly as the temperature goes down. Therefore, an O-ring may seal below the recommended low temperature limit when used as a rod type seal. When excessive side loads are encountered on maximum tolerance rods or glands, and the pressure is in the low range, leakage may occur at temperatures 5°or 8°C (10°or 15°F) above the TR-10 value. It may be necessary to add as much as 22°C (40°F) to the low temperature shown in the tables for this type of service. See Figure 2-27. 2.13.3 Time The three obvious “dimensions” in sealing are fl uid, temperature, and pressure. The fourth dimension, equally important, but easily overlooked, is time. Up to this point, temperature limits, both high and low, have been published at conventional short-term test temperatures. These have little bearing on actual long-term service of the seal in either static or dynamic applications. A comparison of the temperature limits of individual compounds in this guide with previous literature will reveal that for comparable materials the upper temperature limit is more conservatively expressed. The narrower temperature range does not imply that the compounds discussed are inferior to others. Rather, those high temperature values based on continuous seal reliability for 1,000 hours are being recommended. As illustrated by the graph (Figure 2-28), short term or intermittent service at higher temperatures can be handled by these materials. For example, an industrial nitrile (Buna-N) compound, N0674- 70, is recommended to only 121°C (250°F), yet it is known to seal satisfactorily for fi ve minutes at 538°C (1,000°F) and at 149°C (300°F) for 300 hours. Therefore, when the application requires a temperature higher than that recommended in the compound and fl uid tables, check the temperature curve to determine if the total accumulated time at high temperature is within the maximum allowable limit. The sealing ability of a compound deteriorates with total accumulated time at temperature. The curves show the safe, cumulative time at a given temperature for specifi c elastomers used as static seals. For dynamic seal applications, temperatures as much as 14°C (25°F) below those indicated may be more realistic. 2.13.4 Pressure The system operating pressure is always a consideration as it effects the choice of seal materials in several ways. First is hardness, as may be required to resist extrusion in dynamic designs or where there is a large gap between sealed members in static applications. Second is at-rest vs operating conditions and requirements for “leakless” at rest conditions which would suggest due consideration be given to the long-term compression set properties of a given material. Parker Hannifi n Corporation • O-Ring Division 2360 Palumbo Drive, Lexington, KY 40509 Phone: (859) 269-2351 Fax: (859) 335-5128 www.parkerorings.com
100 80 60 40 20 0 °C -50 °F -58 -40 -40 -30 -22 Parker O-Ring Handbook Change in Characteristics According to Temperature on NBR 80 -20 -4 Figure 2-27: Change in Characteristics According to Temperature on NBR 80 Temperature °C (°F) 649 (1200) 593 (1100) 538 (1000) 482 (900) 427 (800) 371 (700) 316 (600) 260 (500) 204 (400) 149 (300) 93 (200) 38 (100) 0 0.1 Shore A (pts) hardness Rebound elasticity (%) Compression set (%) Figure 2-28: Seal Life at Temperature -10 14 Fluoroelastomer 0 32 Ethylene Propylene & Neoprene 10 50 20 68 Temperature 30 86 Seal Life at Temperature Silicone Compound: NBR 80 40 40 Nitrile (High Temperature Type) Nitrile (Low Temperature Type) 50 104 60 122 70 140 General Temperature Limits of Basic Elastomer Compounds 0.5 1.0 5.0 10 50 100 500 1000 Exposure Time — Hours 80 176 Parker Hannifi n Corporation • O-Ring Division 2360 Palumbo Drive, Lexington, KY 40509 Phone: (859) 269-2351 Fax: (859) 335-5128 www.parkerorings.com Basic O-Ring Elastomers 2-27
Page 1 and 2: aerospace climate control electrome
Page 3 and 4: 50 th 50 th 50 th Anniversary Editi
Page 5 and 6: Section I - Introduction 1.0 How to
Page 7 and 8: 1.4 Operation All robust seals are
Page 9 and 10: 1.7.1 Static Seals In a truly stati
Page 11 and 12: 1.11 Comparison of Common Seal Type
Page 13 and 14: Section II - Basic O-Ring Elastomer
Page 15 and 16: 2.1.2 Rubber Rubber-like materials
Page 17 and 18: 2.2.6 Chloroprene Rubber (CR) Chlor
Page 19 and 20: 2.3 Compound Selection and Numberin
Page 21 and 22: O-ring seal, whether static or dyna
Page 23 and 24: Percent Compression 40% 30% 20% 10%
Page 25 and 26: Percent Compression 40% 30% 20% 10%
Page 27 and 28: Compression Set (% ) 100 Figure 2-1
Page 29 and 30: 2.4.12 Thermal Effects All rubber i
Page 31 and 32: coeffi cient of expansion for that
Page 33 and 34: 2.6 Aging Deterioration with time o
Page 35 and 36: A well-known rapid method for mater
Page 37: 2.13.2 Temperature Temperature rang
Page 41 and 42: misapplication might be greatly red
Page 43 and 44: c. Elongation Change Experience wil
Page 45 and 46: is possible to receive a part with
Page 47 and 48: Section III - O-Ring Applications 3
Page 49 and 50: 3.1.2 Temperature Operating tempera
Page 51 and 52: O-Lube has some unique advantages.
Page 53 and 54: Parker Boss Kit Sizes Size Dimensio
Page 55 and 56: Recovery Percent of Original Delect
Page 57 and 58: 3.9.5 Fuels for Automobile Engines
Page 59 and 60: Parker Seal produces a number of co
Page 61 and 62: 3.9.16 Fungus-Resistant Compounds B
Page 63 and 64: 3.9.17.2 Concentrates Containing Mi
Page 65 and 66: Where temperatures do not go below
Page 67 and 68: Permeability Rate - CC/SEC/ATM Effe
Page 69 and 70: Underwriters’ Laboratories Approv
Page 71 and 72: Parker Seal Elastic Drive Belt Comp
Page 73 and 74: Parker O-Ring Handbook Gas Permeabi
Page 81 and 82: Section IV - Static O-Ring Sealing
Page 83 and 84: The 4-3 and 4-7 design charts are o
Page 85 and 86: (e) 0° to 5° (Typ.) 63 Break Corn
Page 87 and 88: 215 1.301 1.305 1.079 1.060 1.063 1
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Guide for Design Table 4-2 If Desir
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Parker O-Ring Handbook Gland Dimens
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Dovetail Grooves It is often necess
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Parker O-Ring Handbook This type of
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F .031 .016 RAD K Parker O-Ring Han
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Gland Detail 0° to 5° Break Corne
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Section V - Dynamic O-Ring Sealing
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When a cylinder rod extends out int
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It can be clearly seen from Figure
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5.11 Friction Friction, either brea
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5-9 Dynamic O-Ring Sealing Parker H
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For the same conditions, friction a
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5.15 Spiral Failure A unique type o
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5.16.1 Small Amount of Leakage 1. E
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Recommended dimensions for fl oatin
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for this service. See Section II, B
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5.30.2 Calculation of Drive Belt Cr
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Parker O-Ring Handbook Gland Design
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124 125 126 127 128 129 130 131 132
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240 241 242 243 244 245 246 247 325
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448 449 450 451 452 453 454 455 456
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X Gland Detail 0° to 5° Break Cor
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5.31.3 O-Ring Glands for Pneumatic
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Parker O-Ring Handbook Design Table
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5.31.4 O-Ring Glands for Rotary Sea
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Parker O-Ring Handbook Rotary O-Rin
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Parker O-Ring Handbook Rotary O-Rin
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Section VI - Back-Up Rings 6.1 Intr
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6.4.2 Metal Non-Extrusion Rings In
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Parker Parbak 8-Series Dimensions (
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Parker Parbak 8-Series Dimensions (
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Back-Up Rings Cross Reference (Cont
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Parker O-Ring Handbook Section VII
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COMPOUND COMPATIBILITY RATING 1 - S
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Section VIII - Specifi cations 8.1
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Military Fluid Specifi cation Descr
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AMS (1) and NAS (2) Rubber Specifi
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Parker O-Ring Handbook Compound Sel
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Section IX Sizes Parker Series 2-XX
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Table 9-1: Parker Series 2-XXX O-Ri
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Parker O-Ring Handbook Parker Serie
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Parker Series 5-XXX O-Ring Sizes (C
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Parker Series 5-XXX O-Ring Sizes (C
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Series 5-XXX Locator Table Size I.D
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Parker O-Ring Handbook Inside Diame
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JIS B2401 Sizes JIS Thickness Inner
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Parker O-Ring Handbook Unusual Size
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Parker O-Ring Handbook Unusual Size
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Section X - Appendix 10.1 O-Ring Fa
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10.1.1.2 Extrusion and Nibbling Ext
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10.1.1.6 Installation Damage Many O
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Parker Seal also has the capability
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10.3 Glossary of Seal and Rubber Te
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Flash: Excess rubber left around ru
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(b) REP (Roentgen equivalent-physic
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10.4 Abbreviations ACM Polyacrylate
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Compound Shrinkage Class Compound N
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Table 10-8: Dimensions From Standar
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Parker O-Ring Handbook Dimensions F
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Appendix 10-32 Parker O-Ring Handbo
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Index — A — Abbreviations. . .
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International O-Ring Standards and
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Offer of Sale 1. Terms and Conditio
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Parker’s Total inPHorm Take the g
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