RXF ROTARY SCREW COMPRESSOR UNITS
MAINTENANCE
070.410-IOM (JAN 12)
Page 22
MAINTENANCE
This section provides instructions for normal maintenance,
a recommended maintenance program, troubleshooting and
correction guides, typical wiring diagrams and typical P and
I diagrams.
This section must be read and un-
derstood before attempting to
perform any maintenance or service
to the unit.
NORMAL MAINTENANCE OPERATIONS
When performing maintenance you must take several pre-
cautions to ensure your safety:
1. IF UNIT IS RUNNING, PUSH [STOP] KEY TO SHUT
DOWN THE UNIT.
2. DISCONNECT POWER FROM UNIT BEFORE PER-
FORMING ANY MAINTENANCE.
3. WEAR PROPER SAFETY EQUIPMENT WHEN COM-
PRESSOR UNIT IS OPENED TO ATMOSPHERE.
4. ENSURE ADEQUATE VENTILATION.
5. TAKE NECESSARY SAFETY PRECAUTIONS REQUIRED
FOR THE REFRIGERANT BEING USED.
CLOSE ALL COMPRESSOR PACK-AGE
ISOLATION VALVES PRIOR TO SER-
VICING THE UNIT. FAILURE TO DO
SO MAY RESULT IN SERIOUS INJURY.
GENERAL MAINTENANCE
Proper maintenance is important in order to assure long and
trouble-free service from your screw compressor unit. Some
areas critical to good compressor operation are:
1. Keep refrigerant and oil clean and dry, avoid moisture
contamination. After servicing any portion of the refrigera-
tion system, evacuate to remove moisture before returning
to service. Water vapor condensing in the compressor while
running, or more likely while shut down, can cause rusting
of critical components and reduce life.
2. Keep suction strainer clean. Check periodically, par ticularly
on new systems where welding slag or pipe scale could
find its way to the compressor suction. Excessive dirt in the
suction strainer could cause it to collapse, dumping particles
into the compressor.
3. Keep oil filters clean. If filters show increasing pressure
drop, indicating dirt or water, stop the compressor and
change filters. Running a compressor for long periods with
high filter pressure drop can starve the compressor for oil
and lead to premature bearing failure.
4. Avoid slugging compressor with liquid refrigerant. While
screw compressors are probable the most tolerant to in-
gestion of some refrigerant liquid of any compressor type
available today, they are not liquid pumps. Make certain
to maintain adequate superheat and properly size suction
accumulators to avoid dumping liquid refrigerant into com-
pressor suction.
Keep liquid injection valves properly adjusted and in good
condition to avoid flooding compressor with liquid. Liquid can
cause a reduction in compressor life and in extreme cases
can cause complete failure.
5. Protect the compressor during long periods of shut down.
If the compressor will be setting for long periods without run-
ning it is advisable to evacuate to low pressure and charge
with dry nitrogen or oil, particularly on systems known to
contain water vapor.
6. Preventive maintenance inspection is recommended any
time a compressor exhibits a noticeable change in vibra tion
level, noise or performance.
COMPRESSOR SHUTDOWN and START-UP
For seasonal or prolonged (six months) shutdown, use
the following procedure:
1. Push
[STOP]
key to shut down unit.
2. Open disconnect switch for compressor motor starter.
3. Turn off power.
4. Isolate the package by closing all package valves to the
system. Tag all closed valves.
Open any solenoid valves orother
valves that may trap liquid
between the isolation valves and
other package valves to prevent injury or damage to
components.
5. With liquid injection, close the manual hand valve up-
stream of the solenoid and manually open the solenoid by
turning “in” the manual opening stem (clockwise viewed
from below valve).
6. Shut off the cooling water supply valve to the oil cooler.
Drain water, if applicable. Attach
CLOSED
tags.
7. Protect oil cooler from ambient temperatures below
freezing.
NOTE: The unit should be inspected monthly during
shutdown. Check for leaks or abnormal pressure. Use the
maintenance log to record readings to verify the pressure
stability of the unit. To prevent the seals and bearing from
drying out, run oil pump (if available) and manually rotate
the compressor shaft. Consult motor manufacturer for
motor recommendations.
TO START UP AFTER SEASONAL OR PROLONGED SHUT-
DOWN, USE THE FOLLOWING PROCEDURE :
1. Perform routine maintenance. Change oil and replace
filters. Check strainers.
2. Any water necessary for the operation of the system that
may have been drained or shut off should be restored or
turned on.
3. Reset solenoid valves to automatic position, then open all
valves previously closed. Remove tags.
4. Compressor unit is ready for prestart checks. Refer to
PRESTART CHECKLIST
.
COMPRESSOR/MOTOR SERVICING
Before removing the motor from an RXF unit, it is criti-
cal that proper support be provided for the compressor to
prevent damage to the oil separator. Insert blocks or a jack