Chapter 6 Troubleshooting
UD-series Screw Compressors
6-6
Trouble
Direct causes
Factors
Actions
07
Leak from
mechanical
seal
Long stoppage
period (no oil film
on sliding surfaces)
Due to user’s
specific conditions,
such as heat load
being intermittent.
If stoppage period becomes more
than one week, manually operate oil
pump as well as manually turn
compressor rotor shaft, or equip
external seal portion with oil pot.
Deteriorated parts
Hardened O-ring
For aging degradation, replace
O-ring.
For other specific causes, the same
factors and actions described above
of “Damaged sliding surface due to
excessive heat of sliding surface”
can be applied.
Swelled O-ring
* Occurs in
excessive
refrigerant
dissolution oil
For liquid backflow operation,
remove the causes.
For malfunction of oil heater and
other devices on control circuit,
replace them.
Deteriorated seal
ring or mating ring
For aging degradation, replace
parts.
For other specific causes, the same
factors and actions described above
of “Damaged sliding surfaces due to
excessive heat of sliding surface”
can be applied.
Incompatibility
between operating
conditions (working
temperature
ranges, refrigerant,
etc.) and lubricant
Inappropriate lubri-
cant or change in
operating
conditions since
installation of
compressor.
Re-examine operating conditions if
possible.
If not, refer to Chapter 4.1,
“Lubricant (Refrigerant Oil)”, and
re-select lubricant and replace all
amount of current lubricant with new
type.
Inappropriate
contact conditions
of sliding surfaces
Foreign matter
attached to sliding
surfaces due to
contamination of
lubricant
Exchange all lubricant.
Equip oil supply line with bypass
filter.
Faulty parts attach-
ment
Human error
Overhaul compressor to replace
parts, and reassemble it.
Check using assembly check sheet.
08 Squeaking
sound from
mechanical
seal part
During initial period
after replacement
until sliding surface
fits each other,
squeaking sound
caused by contact
of sliding surfaces
might be heard.
Sliding surfaces is
high in hardness as
well as in density,
so it takes a while
for them to fit each
other.
Squeaking itself does not cause
seal leak or functional deterioration
of seal.
Squeaking normally subsides after
few dozens of hours, but it could
continue in rare cases.
→
In this case, contact our service
centers.
