2200LZJE-HO-C6-N_2013.12.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 2016**C
6-9
Symptom Direct cause Root cause Action
12
Compressor
generates
abnormal
vibration
and/or
sound.
M rotor shaft
vibrates
excessively.
Thrust bearing
glands are
tightened unevenly.
If lock nuts are not loose and parts
such as thrust bearing are free of
defects, tighten the glands evenly.
Thrust bearing
glands get
loosened.
Lock washer claw not bended, or
thrust bearing rolling elements
(balls) are worn.
→ Check the thrust bearing. If any
defect is found, replace it, and then
reassemble it after adjusting end
clearance and checking shaft
runout.
Rotor dynamic
balance is
disturbed.
If no other causes are found for
abnormal vibration, or if on-site
overhaul only has been repeatedly
performed for a long time, this may
be the cause.
→ Overhaul the compressor at a
place where a dynamic balance
measurement/adjustment system is
available, such as the MAYEKAWA
Moriya Factory.
Oil hammer Continuous
low-load operation
with capacity
control not greater
than 30%
During low-load operation, lubricant
is difficult to be discharged. As a
result, oil that stays between the
engaged rotors increases and gets
compressed.
→ Avoid continuous low-load
operation as far as possible.
* Especially when the fluid is light
gas (He, NH3, etc.), continuous
operation of merely 10 minutes
can cause bad effect. The
maximum limit should be 30
minutes even for fluorocarbon
fluids.
Liquid flow-back
during startup
* Loud abnormal
noise at startup.
* If this is heard, the
compressor may
get damaged
instantaneously.
Refrigerant
liquefies and stays
inside upstream
piping when
equipment is
stopped.
There are many probable causes,
such as a leak inside liquid supply
solenoid valve on the load side,
insufficient heat exchange
(refrigerant evaporation) in heat
exchanger, or trapping due to
mis-piping in the piping line.
→ Identify the cause(s) and take
necessary measures. Then
overhaul and inspect the
compressor.
Liquid flow-back
during operation
Aperture of liquid
supply expansion
valve is large.
In case of temperature-type
expansion valve, check the
condition of temperature sensitive
cylinder and capillary tube. If any
defect is found, take necessary
actions.
If orifice gets unsuitable due to the
change in operating conditions,
replace the orifice.
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