070.610-IOM (JUL 21)
Page 33
RWF II Rotary Screw Compressor Units
Maintenance
Maintenance
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 sitting for long periods
without running it is advisable to evacuate to low pressure
and charge with dry nitrogen or oil. This is particularly true
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 shutdowns the following proce
-
dure should be followed:
1.
Reduce the system pressure to the desired condition.
2.
Press
[STOP]
key to cease operation of the compressor.
3.
Open disconnect switches for compressor motor and oil
pump starters.
4.
Turn on oil heater circuit breaker.
5.
Close suction and discharge service valves, also liquid
injection and economizer service valves, if applicable.
Attach CLOSED TAGS
.
6.
Shut off cooling water supply valve to oil cooler, if ap
-
plicable.
Attach CLOSED TAG
.
7.
Protect oil cooler from ambient temperatures below
freezing or remove water heads.
To start up after a seasonal or prolonged shutdown the fol
-
lowing procedure should be followed:
1.
Any water necessary for the operation of the system
that may have been drained or shut off should be restored
and turned on.
2.
Open suction and discharge service valves, also liquid
injection and economizer service valves, if applicable. Remove
tags.
3.
Close disconnect switches for compressor, motor and oil
pump starters.
4.
Turn off oil heater circuit breaker.
5.
Perform checkpoints on prestart check list, then start
unit.
General instructions for replacing
compressor unit components
NOTICE
See Publication 070.660-SM for procedures covering
replacement motor and compressor mounting.
When replacing or repairing components which are ex
-
posed to refrigerant pressure (including suction strainer)
proceed as follows:
1.
Push
[STOP]
key on control panel to shut down unit.
2.
Open disconnect switches for compressor and pump
motor starters.
3.
Close suction and discharge service valves, also liquid
injection and economizer service valves, if applicable.
General information
This section provides instructions for normal main tenance,
a recommended maintenance program, troubleshooting and
correction guides, and typical P and I diagrams. For typical
wiring diagrams and information about the
Quantum
™
HD
control panel, refer to
090.040-M.
WARNING
This section must be read and un der stood be-
fore attempting to perform any main tenance or
service to the unit.
Normal maintenance operations
When performing maintenance you must take several
precau tions to ensure your safety:
WARNING
1. If unit is running, press [stop] key.
2. Disconnect power from unit before performing any
maintenance.
3. Wear proper safety equipment when compressor
unit is opened to atmosphere.
4. Ensure adequate ventilation.
5. Take necessary safety precautions required for the
refrigerant being used.
WARNING
Close all compressor package isolation valves prior
to servicing 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 mois
-
ture contamination. After servicing any portion of the
refrigera tion system, evacuate to remove moisture before
returning to service. Water vapor condensing in the com
-
pressor 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 probably the most tolerant to in-
gestion of some refrigerant liquid of any compressor type
available today, they are not liquid pumps. Ensure to maintain
adequate superheat and properly size suction accumulators
to avoid dumping liquid refrigerant into compressor suction.