2205B0JE-DA-J-N_2014.05.
6 Troubleshooting
Screw Compressor J-series
6-11
Trouble
Direct causes
Factors
Actions
11
Abnormal
vibration
and/or
noise of
compressor
Damage to thrust
bearing
Aging degradation
(exceeded
appropriate time for
replacement)
Appropriate time for replacement
will differ due to operating
conditions (if low pressure or
intermediate pressure is high, life of
thrust bearing becomes shorter)
and oil management conditions.
However, if used under standard
refrigerating usage based on steady
continuous operation, inspect and
replace it after 40000 hours or
within 5 years.
For details, refer to chapter 5.2.3 in
this manual.
Liquid backflow
operation
Refer to the Direct causes “Liquid
backflow during startup” and “Liquid
backflow during operation” above in
this item.
Contamination of
foreign substances
Refer to the Direct cause “Foreign
substances contaminating
compressor” above.
Excessive thrust
stress other than
above
High suction
pressure
exceeding op-
erating conditions
Re-examine operating conditions
and improve them if possible.
If it is difficult to improve,
re-examine maintenance interval
management.
Faulty assembly
* Lock nuts
tightened
insufficiently, lock
washer tab not
bended, rotation
stopper not set to
thrust bearing
gland, gland not
assembled, etc.
Tighten lock nuts by using
specified torque.
Be sure to record data on the
assembly check sheet to prevent
omission of work steps.
Sympathetic
vibration
This phenomenon
occurs when vibra-
tion approaches the
natural frequency of
the whole vibration
system for the
machinery,
including piping and
support.
In many cases, this occurs due to
change in installation environment
such as change in piping circuit or
additional installation of devices in
the machine room, and changes in
oil levels.
→
If sympathetic vibration is
suspected, contact our sales
offices or service centers.
