2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 4032**C
6-11
12: Compressor generates abnormal vibration and/or sound (continued)
Direct cause
Root cause
Action
Foreign substances
entering the
compressor
Welding spatter, etc.
flowing from upstream
side
Check suction strainer and/or oil filters. Replace
element if defective.
Overhaul the compressor.
Collect foreign substances and identify their
sources. Then take necessary actions.
Tools and/or waste
cloth left uncollected
after overhauling
Damaged thrust
bearings.
Deterioration over time
(operated beyond
recommended time of
replacement)
The time for replacement depends largely on
operating conditions (low pressure or high
intermediate pressure will make the life shorter,
etc.) and/or oil management conditions. In case of
a typical refrigeration application which basically
operates in a stable continuous mode, inspect and
replace them every 40,000 hours or 5 years,
whichever comes first.
For details, see Chapter 5, Section 5.2.3 in this
manual.
Operation with liquid
flow-back
Refer to causes of "Liquid flow-back during
startup" and "Liquid flow-back during operation" in
item 12.
Entry of foreign
substances
Refer to causes of "Foreign substances entering
the compressor" above.
Excessive thrust stress
other than above
・
High suction
pressure/intermediate
pressure exceeding
the level set by
operating conditions
Re-examine operating conditions, and improve if
possible.
If difficult to improve, review maintenance interval.
Faulty assembly
* Lock nuts tightened
insufficiently, lock
washer tooth not
bended, rotation
stopper not set to
thrust bearing gland,
gland not assembled,
etc.
Tighten lock nuts by using specified torque or
torque angle (see Chapter 7, "7.3 Tightening
Torques for Bolts and Nuts" in this manual).
Be sure to record data on the assembly check
sheet to prevent omission of work steps.
Resonance vibration
This occurs when the
frequency of vibration
comes close to the
natural frequency of
any component in the
entire vibrating system,
including pipes and
supports.
In many cases, this symptom is caused by change
in installation environment (such as change in
piping routes or additive installation of devices in
the machine room, oil level change, etc.)
→If occurrence of resonance vibration is a
suspected, contact our service center.
