Section 5
OPERATION
22
5.2 PURPOSE OF CONTROLS-- STANDARD ELECTRO/MECHANICAL (CONTINUED)
CONTROL OR INDICATOR PURPOSE
SEPARATOR RETURN LINE SIGHT GLASS Used to indicate fluid flow in the return line. When the
compressor is running at full load, fluid flow should be
visible in this sight glass. There may be little or no flow
when the compressor is running unloaded, but a slug-
gish flow at full load indicates a need to clean the re-
turn line strainer.
THERMAL VALVE Regulates flow of fluid to and around the cooler. It is de-
signed to maintain a minimum operating temperature
of 180_F(82_C ) ; u s e f o r f a s t w a r m --- u p o n s t a r t --- u p .
MINIMUM PRESSURE/CHECK V ALVE Maintains minimum of 55 psig (3.8 bar) in the com-
pressor sump. Valve piston restricts receiver air dis-
charge from receiver/sump when pressure falls to 55
psig (3. 8 bar). Also prevents backflow into the sump
during unload conditions and after shutdown.
COMPRESSOR DISCHARGE Designed to shut the compressor down when the
TEMPERATURE SWITCH discharge temperature reaches 235_F (113_C).
WATER PRESSURE SWITCH It prevents operation when water pressure of
(water---cooled compressors only) compressor is inadequate.
PRESSURE RELIEF VALVE Opens sump pressure to the a tmosphere should pres-
sure inside the sump become too high. Operation of
this valve indicates that the high pressure switch is ei-
ther faulty or out of adjustment.
MODULATING INLET VALVE Regulates the amount of air allowed to enter the air
compressor. This regulation is determined by the
amount of air being used at the service line. Also acts
as a check valve to prevent reverse compressor rota-
tion at shut down.
PRESSURE REGULATOR Allows a pressure signal to reach the air inlet valve to
control air delivery according to demand.
SOLENOID VALVE Bypasses the pressure regulator valve causing the in-
let valve to close when the compressor reaches maxi-
mum operating pressure. Also activates blow ---down
valve.
PRESSURE SWITCH Senses service line pressure. When line pressure
reaches maximum setting the pressure switch signals
the pilot valves to unload the compressor.
BLOWDOWN VALVE Vents sump pressure to the atmosphere during un -
load conditions and shutdown.
WATER REGULATING VALVE Regulates the amount of cooling water used to keep
(water---cooled only) the compressor running at a normal operating tem---
perature.
5.3 INITIAL START-- UP PROCEDURE--STANDA RD
ELECTRO/MECHANICAL
The following procedure should be used t o make
the initial start---up of the compressor:
1. Read the preceding pages of this manual thor-
oughly.
2. Be sure that all preparations and checks de-
scribed in the Installation Section have been
made.
3. Crack open t he shut off valve to the service line.
4. Start the compressor by pushing the START but-
ton.
5. Check for possible leaks in piping.
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