Heavy Duty Balanced Opposed Compressors - Ariel Corporation

Section 3 - Maintenance For Models: JGH:E:K:T
1. For new divider valves, verify working piston section fastener torque is 75 lb-in. Loosen the section
fasteners, then step-torque them first to 40 lb-in, and then to 75 lb-in. Used divider valves
can be tested “as is”, with approximate section fastener torque verified after testing.
6. Place the distribution block in an open container with all base outlets open. Connect purge gun
filled with room temperature (65°F) 10 wt. (ISO 32) mineral oil to the divider block inlet. Pump the
purge gun to purge air from the divider block assembly. Verify that oil flows freely from all outlets
(see Fig. 3-8 “Divider Block All Outlets Open”).
Testing with 10 wt. mineral oil at 65°F simulates divider block operation at 120°F with 40 wt. (ISO
150) mineral oil. If 10 wt. mineral oil is unavailable, use 40 wt. (ISO 150); however, the pressure
test will be less sensitive in detecting a bypassing divider valve.
7. The divider block assembly should cycle at less than 300 psi while purging at a steady rate.
Cycle pressures above 300 psi indicate inhibited piston movement, possibly caused by the piston
rubbing the bore, oil contamination, part geometry, or bore distortion due to over-tightening the
section fastners.
8. For divider valves stamped with a “T” (for “twin”), use a 1/8 inch pipe or tubing plug to plug only
one base outlet when testing that side of the piston, and leave all other outlets open. Plug and
test each base outlet of divider valves stamped with a “T” one side at a time. See Fig. 3-8 “Testing
‘T’ Divider Valve”. Individual testing of each outlet ensures both sides of the piston build adequate
pressure. For all divider valves stamped with an “S” on the front (for “single”), leave the one
side plugged and plug the other outlet as well to test both sides of the piston for by-passing
simultaneously. See Fig. 3-8 “Testing ‘S’ Divider Valve”.
9. Pump the purge gun until the pressure gauge indicates 3000 psi. Hold this pressure for 5 seconds,
then increase it to 3500 psi. Stop pumping at 3500 psi.
10. Start timer and monitor the pressure drop from 3500 psi for 30 seconds. Check discharge outlet(s)
plug(s) to confirm no external leaks. If the valve bypasses rapidly, repeat the test to ensure
the bypass wasn’t due to trapped air. New valves should not exceed a 400 psi pressure drop in
30 seconds. Used valves should not exceed 1000 psi pressure drop in 30 seconds. If pressure
drops exceed these limits, the divider valve fails the test.
11. Repeat Steps 4 thru 6 for the remaining outlets on the divider block assembly.
NOTE: Test distribution blocks at higher pressures if the application dictates higher system
operating pressure.
If a divider valve fails, replace it. Discard worn divider valves. If the tested valve passes the test,
relieve the pressure, move the plug to the next outlet, and repeat the test for all divider valves. When
all divider valves either pass this pressure test or are replaced, reassemble the distribution block,
purge it with the proper force feed lubricant, and put it into service.
This distribution block pressure test procedure is not infallible. Ariel recommends periodic tests for
proper cylinder bore lubrication rates and/or aftermarket devices that measure flow.
Balance Valves
Install balance valves on low-pressure lube lines to artificially increase lube line pressure and reduce
differential pressure between lube points downstream of a divider block. Important considerations:
• Set and maintain balance valves downstream of a divider block within 500 psi (3400kPa) of each
other or less. The closer the balance valve set pressures, the more reliable the system.
• Avoid situations in which the balance valve set pressure is the greatest contributor of pressure to
the divider block immediately upstream.
• With a balanced divider block, the upstream divider block pressure gauge should exhibit no erratic
needle movement as the divider block cycles.
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