Section 5
OPERATION
24
5.2 PURPOSE OF CONTROLS
CONTROL OR INDICATOR PURPOSE
FL UID LEVEL SIGHT GLASS Monitors fluid level in the sump. Proper level should fill
the sight glass. Check the level when the compressor
is shut down. DO NOT OVERFILL.
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.
FL UID STOP VALVE Cuts off flow of fluid to compressor unit at compressor
shutdown and allows flow of fluid to the unit on start---
up.
DISCHARGE CHECK VALVE Cuts off the reverse flow of air/fluid mixture through
compressor discharge system at compressor shut-
down.
THERMAL VALVE Regulates flow of fluid to and around the cooler. De-
signed to maintain a minimum operating temperature
of 170_F(77_C); used for fast warm---up on start---up.
MINIMUM PRESSURE/CHECK VALVE Maintains minimum of 50 psig (3.4 bar) in the com-
pressor sump. Valve piston restricts receiver air dis-
charge from receiver/sump when pressure falls to 40
psig (2.8 bar). Prevents line pressure backflow into
the sump during unload conditions and after shut-
down.
COMPRESSOR DISCHARGE The Supervisor will shut the compressor down when
TEMPERATURE PROBE (T1) the discharge temperature reaches 235_ F (113_C).
The message displays “HIGH TEMP T1”.
SUMP PRESSURE TRANSDUCER (P1) The Supervisor will shut the compressor down if the
sump pressure becomes too high. This valve is facto-
ry set per the designed operating range of the com-
pressor; normally 135 psig (9.3 bar). P1 status in con-
junction with the status of the “compressor run” out-
put contact determines if compressor is running. If the
run contact is closed, the compressor is ON LOAD,
and P1 is below 14.5 psig (1bar), the Supervisor will
initiate a shutdown and display a “Pressure Loss”
message.
INJECTION FLUID PRESSURE The Supervisor will initiate a protective shutdown
TRANSDUCER (P3) and display a “Low Pressure P3” message if the
fluid pressure goes below a factory set minimum
value; approximately 10 psig (0.7 bar).
FL UID FILTER TRANSDUCER (P4) Used in conjunction with P3 to calculate fluid filter dif-
ferential pressure and warn of need for filter replace-
ment.
WATER PRESSURE SWITCH Prevents compressor operation if water pressure is
(water---cooled compressors only) too low. Standard setting is 10 psig (0.7 bar). The
message “FAN OL/LO WATER” will be displayed if
pressure is too low.
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