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4-5
Inlet Feed Valve (R)
- This device supplies/vents the required pressure signal to actuate the inlet
butterfly valve. When energized, the 3-way solenoid valve opens the inlet butterfly valve and when de-
energized, it allows it to close. See Inlet Control (Butterfly) Valve, Section 10, page 74, for details.
Oil Flow Control Valves (U)
- These devices feed a regulated amount of oil into various areas of the 1st
stage compressor and inter-stage manifold, in order to maintain optimal 1st and 2nd stage compressor
discharge temperatures (between 195
°
F and 220
°
F). See Section 5, page 41
“Lubrication System”, for
detailed information on their operation.
Check Valve – Auxiliary Purge (V)
- This device supplies air to 1st stage compressor during
“empty
system
” startup.
Ball Valve – Oil Drain (W) -
This device allows the drainage of oil entrapped within the compressors,
interstage pipe, and oil separation vessel during oil change operation.
Check Valve – Oil Flow Control (X)
- This devices prevent the reversal of oil flow from the higher
pressure into lower pressure regions of the oil system.
Air Filter Vacuum Switch (Y)
- This device measures the vacuum pressure at the discharge side of the
inlet air filter. When air filter vacuum reaches 30
” inches of water, it triggers the controller to advise the
user that the filter requires service or replacement.
Blow Down Valve (S)
- This (two-way solenoid) device vents compressed air from the air/oil reservoir.
During compressor operation (e.g., compressors are running or they have temporarily stopped due to line
pressure reaching unload pressure), the blow down valve remains energized (closed) and the air/oil
reservoir remains pressurized. When compressor operation is halted (e.g., by use of the red
“STOP”
controller button, by loss of electrical energy, or by a shutdown condition), the valve is de-energized
(normally open state) and the air/oil reservoir is blown down
.