Section 5
COMPRESSOR OPERATION
18
5.2 PURPOSE OF CONTROLS -- STANDARD (CONTINUED)
CONTROL OR INDICATOR PURPOSE
LINE PRESSURE GAUGE Continually monitors service line air pressure.
DISCHARGE TEMPERATURE GAUGE Monitors temperature of the air/fluid mixture dis-
charged from the compressor unit. For air--cooled
compressors normal reading is approximately 185
_
F
(85
_
C ) with a 70
_
F(21
_
C) ambient temperature.
FLUID FILTER MAINTENANCE GAUGE Indicates when a filter element change is required.
FLUID SEPARATOR MAINTENANCE GAUGE Indicates when separator element change is required.
AIR FILTER MAINTENANCE INDICATOR Shows red when air filter element servicing is required.
This indicator must be manually reset after servicing
filter.
PRESSURE REGULATOR Opens a pressure line between the sump and air inlet
valve allowing the inlet valve to regulate air delivery ac-
cording to demand.
FLUID LEVEL SIGHT GLASS Indicates fluid level in the sump. Proper level is not to
fall below the center of the sight glass. Check level
when compressor is shut down.
DO NOT OVERFILL.
COOLER BYPASS VALVE Regulates flow of fluid to and around the cooler .
Designed to maintain a minimum operating
temperature of 185
_
F(85
_
C); used for fast
warm--up on start--up.
MINIMUM PRESSURE/CHECK VALVE Maintains minimum of 50 psig (3.4 bar) in the compres-
sor sump. Valve piston restricts receiver air discharge
from receiver/sump when pressure falls to 50 psig (3.4
bar). Also incorporated in this valve is a terminal check
valve which prevents line pressure backflow into the
sump during unload conditions and after shutdown.
DISCHARGE TEMPERATURE SWITCH Shuts the compressor down when the discharge tem-
perature exceeds 240
_
F(116
_
C).
PRESSURE RELIEF VALVE Protects compressor by venting compressed air in ex-
cess of 200 psig (13.8 bar) to atmosphere.
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.
SOLENOID VALVE Bypasses the pressure regulator valve causing the in-
let valve to close when the compressor reaches maxi-
mum operating pressure. Also activates blowdown
valve.
W ATER REGULATING VALVE Regulates the amount of cooling water used in the
(water--cooled only) cooler to keep the the compressor running at a normal
operating temperature of 185
_
F(85
_
C).
SUMP PRESSURE GAUGE The sump pressure gauge is used to determine at start--
up whether proper electrical connections were made for
motor rotation. An immediate pressure reading indicates
proper rotation of the compressor unit. It can also be
used to verify a pressure drop in the system.
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