RWB II ROTARY SCREW COMPRESSOR UNITS
MAINTENANCE
070.200-IOM (DEC 11)
Page 40
TROUBLESHOOTING THE LIQUID INJECTION OIL COOLING SYSTEM
TROUBLESHOOTING THE DEMAND PUMP SYSTEM
SYMPTOM PROBABLE CAUSES and CORRECTIONS
HIGH OIL TEMPERATURE Insufficient liquid supply, check receiver level and pressure drop at injection solenoid.
Equalizer pressure too high, lower.
Suction superheat too high, correct system problem.
Thermal valve power head lost charge, replace.
Liquid strainer blocked, clean.
Liquid solenoid coil failed, replace.
Excessive load. Thermovalve undersized. Reduce load or install larger thermovalve.
LOW OIL TEMPERATURE Equalizing pressure too low, raise.
Suction superheat too low or liquid coming back on compressor, correct system problem.
Low load conditions. Valve oversized, increase load or use smaller thermovalve.
OIL TEMPERATURE FLUCTUATES
System conditions rapidly fluctuate causing liquid injection system to over
respond, stabilize system operation.
SYMPTOM PROBABLE CAUSES and CORRECTIONS
PUMP WILL NOT PRODUCE
ENOUGH OIL PRESSURE
TO START COMPRESSOR
Check pump rotation.
Check that service valves are open.
Filter cartridges may be blocked. Check PSID across filters.
Strainer may be blocked. Clean.
Oil pressure regulator set too low or stuck open. Readjust or repair.
Pump worn out. Repair or replace.
OIL PRESSURE RAPIDLY DROPS
OFF WHEN COMPRESSOR STARTS
RESULTS IN COMPRESSOR
DIFFERENTIAL ALARM
Main oil injection throttling valve too wide open or oil pressure regulating valve
improperly adjusted. Readjust both valves.
OIL PRESSURE FLUCTUATES
Liquid injection overfeeding or refrigerant flood back from system. Make
necessary adjustments or correc tions
NOISE and VIBRATION
Pump strainer blocked. Clean.
Liquid refrigerant overfeed. Adjust liquid injec tion.
Pump worn out. Repair or replace.
GREASE LEAKS FROM VENT PORT
IN THE SIDE OF THE PUMP BODY
Normal leakage which will cease after initial operation. Black oil leaking from this vent
indicates oil seal wear or failure. If leakage exceeds normal allowable rate of 7 drops
per minute, replace seal.
OIL PRESSURE DROPS AS HEAD
PRESSURE INCREASES
Normal behavior. Set main oil injection and oil pressure for maximum head pressure condition.
MAIN FILTER PSID IS TOO HIGH Filters clogged with dirt. Replace.
Oil is too cold. Allow oil to warm up and check again.
Service valve on filter outlet is partially closed. Open valves fully.
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