Chapter 6 Troubleshooting
UD-series Screw Compressors
6-3
Trouble
Direct causes
Factors
Actions
04
Low
oil-supply
pressure
Defect in hydraulic
pressure detection
divices.
Malfunction in
hydraulic pressure
protection
device(switch),
pressure sensor,
relays, etc.
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
devices.
Clogging in the
tubing for oil
pressure protection
switch.
Remove clogging. Check oil
contamination level and replace oil
as necessary.
05
Abnormal
high
pressure
(abnormal
discharge
pressure)
Heat exchange
failure at condenser
(heat exchanger)
Contaminated and
blocked heat
exchanger tubes,
fins, etc.
Clean and wash them.
Use solvent to clean depending on
contamination.
Malfunction of fan
motor,
thermo-switch,
water spray bars,
cooling water
pumps, etc.
(including shortage
or out of water)
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
devices.
Flow volume
adjustment failure
of cooling water,
brine, etc.
If regulating valve is manually
adjusted, readjust it.
If an automatic control valve
(including wax valve) is used,
examine its cause and take
measures.
Other causes of
insufficient
circulation volume
of cooling water,
etc.
Inspect for clogging and
contamination of filters for
circulation route filters, and take
measures as needed.
Inspect for leak in circulation routes,
and take measures if any.
Inspect water supply routes and
systems, and take measures as
needed.
If frozen, resolve by better
insulation or heating.
Shortage in
capacity of heat
exchanger.
If the trouble is caused by change in
operating conditions, re-examine
the conditions to improve.
If the trouble is caused by change in
installation environment, improve
the environment if possible.
For both cases, if it is difficult to
improve, add more heat exchanger
or increase their sizes.
Uncondensed gas
in the system
Intake air to low
pressure side
through pinholes,
cracks,
corrosions and
other defective
areas.
Inspect for leak, and take necessary
measures.
Then, air purge the heat exchanger.
