RWB II ROTARY SCREW COMPRESSOR UNITS
MAINTENANCE
S70-200 IOM
Page 39
TROUBLESHOOTING THE LIQUID INJECTION OIL COOLING SYSTEM
SYMPTOM
PROBABLE CAUSES and CORRECTIONS
HIGH OIL TEMPERATURE
Insuffi cient 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 fl uctuate causing liquid injection system to over
respond, stabilize system operation.
TROUBLESHOOTING THE DEMAND PUMP SYSTEM
SYMPTOM
PROBABLE CAUSES and CORRECTIONS
PUMP WILL NOT PRODUCE
Check pump rotation.
ENOUGH OIL PRESSURE
TO START COMPRESSOR
Check that service valves are open.
Filter cartridges may be blocked. Check PSID across fi lters.
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
Main oil injection throttling valve too wide open or oil pressure
OFF WHEN COMPRESSOR STARTS
regulating valve improperly adjusted. Readjust both valves.
RESULTS IN COMPRESSOR
DIFFERENTIAL
ALARM
OIL PRESSURE FLUCTUATES
Liquid injection overfeeding or refrigerant fl ood 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
Normal leakage which will cease after initial operation. Black oil leaking
IN THE SIDE OF THE PUMP BODY
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
Normal behavior. Set main oil injection and oil pressure for maximum head
PRESSURE INCREASES
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 fi lter outlet is partially closed. Open valves fully.
