Heavy Duty Balanced Opposed Compressors - Ariel Corporation

FOR MODELS: JGZ AND JGU SECTION 4 LUBRICATION
Pressure Testing For Divider Valve By-Passing
Divider valve piston to bore are metal to metal sealing surfaces. Lubricant by-passing can
result from excessive clearance between the piston and bore due to wear. Pressure test all
divider blocks that are in service yearly, and replace any divider valves that fail to pass. Testing
helps to ensure the piston to bore clearances are close enough to build adequate pressure
to force oil into the injection point. All new Ariel divider valves are provided pressure tested by
the supplier.
To test divider blocks for valve by-passing, a manual purge pump equipped with a pressure
gauge, and capable of developing 5000 psig (350 bar g ) is necessary. Such a force feed lubrication
system purge gun (hand pump kit) with a pressure gauge is available from Ariel as an
optional purchase tool. For pressure testing the divider block use a 10-weight oil at room temperature
to simulate a hot lubricant. Test each divider block assembly complete with pin indicators
installed. Test only one divider valve at a time.
Place the divider block assembly in an open container with all base outlets open. Connect the
purge pump to the inlet of the divider block assembly. Operate the purge pump to cycle the
divider block several times to purge air from the assembly and verify that oil will flow freely
from all outlets. Divider blocks should cycle at less than 300 psig (21 bar g ). See Figure 4-5:
“Divider Block All Outlets Open”.
Divider valves stamped with a “T” are to have only one outlet on the base plugged during testing
of that side of the piston. Each base outlet of the divider valves stamped with a “T” must be
plugged and tested one side at a time. See Figure 4-5: “Testing “T” Divider Valve”. Individual
testing of each outlet ensures both sides of the piston will build adequate pressure. All divider
valves stamped with an “S” on the front are to have both outlets on the base plugged to test
for by-passing. See Figure 4-5: “Testing “S” Divider Valve”. This will test both sides of the piston
at the same time.
Plug the outlet on the base behind the divider valve being tested with a 1/8 inch pipe plug. If a
tubing fitting is installed in the base, plug the fitting with a tubing plug. Leave all other outlets
open. Operate the purge gun until the pressure gauge indicates 3000 psig (207 bar g ). The
block may cycle once or twice, but should pressurize to 3500 psig (241 bar g ) immediately.
Stop pumping oil into the divider block at 3500 psig (241 bar g ). Check the plug(s) in the discharge
outlet(s) to confirm there are no external leaks. If the pressure gauge on the purge gun
drops suddenly and oil squirts from the other outlets, a by-pass condition exists. The piston is
worn and is allowing oil to by-pass. The pressure gauge should not lose more than 1000 psig
(69 bar g ) during a 30-second test period. Note: Testing the divider blocks at higher pressures
is necessary if the application dictates a higher system operating pressure.
If a divider valve does not pass, it must be replaced. Discard worn divider valves. If the tested
valve does not lose more than 1000 psig (69 bar g ) in 30 seconds, relieve the pressure, move
the plug to the next outlet and repeat the test for all divider valves. When divider valves have
passed pressure testing to this procedure or have been replaced, a divider block may be reassembled,
purged with the proper force feed lubricant being used and put into service.
By the nature of this divider block pressure testing procedure, in a static position through the
divider valves above, it is not infallible. Periodic testing for proper lubrication rates in the cylinder
bore and/or aftermarket devices that measure flow are recommended.
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