Section 5
OPERATION- ELECTRO-MECHANICAL
26
5.2 PURPOSE OF CONTROLS--STANDARD ELECTRO-MECHANICAL (CONTINUED)
CONTROL OR INDICATOR PURPOSE
FLUID LEVEL SIGHT GLASS Monitors fluid level in the sump. The fluid must be vis-
ible in the glass. Check the level when the compressor
is shut down. Maximum fill level is the level of the fill
port, minimizing the risk of overfilling.
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 return
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); use for fast warm--up on start--up.
MINIMUM PRESSURE/CHECK VALVE Maintains minimum of 55 psig (3.8 bar) in the compres-
sor sump. Valve piston restricts receiver air discharge
from receiver/sump when pressure falls to 55 psig (3.8
bar). Also prevents backflow into the sump during un-
load 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 atmosphere should pres-
sure inside the sump become too high. Operation ofthis
valve indicates that the high pressure switch is either
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 usedat theservice line. Alsoactsas
acheck valveto prevent reversecompressor rotation 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 pressureregulator valve causing the inlet
valve to close when the compressor reaches maximum
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 unload
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 temp--
erature.
T1 (AUTOMATIC STOP TIMER) Adjustable from three (3) to 60 minutes. Located on
rear of the controller.
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