2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 4032**C
6-6
08: Leak from mechanical seal
Direct cause
Root cause
Action
Initial leak after
replacement until sliding
surfaces settle
In some cases, immediately
after replacement, the
compressor-specific operating
conditions and the pressure
receiving conditions of
machined sliding surface is
unstable.
In case of initial leak, although leak
amount might increase temporarily, it
will decrease gradually. Check that
leak does not increase continuously.
Duration of initial leak depends on
design/operating conditions. It is
approximately 200 hours, as a rough
indication.
Sliding surface is
roughened due to
overheating.
Started and stopped too many
times.
* In case of standard
equipment, "four or more
times per hour" is considered
"frequent/too many".
If heat load is less than the level set
by the equipment's design conditions,
review the operating conditions and
set control such that equipment is
started/stopped less frequently.
In case of capacity control
malfunction, see "Capacity control
malfunction" in item No. 11.
Excessive refrigerant solved
into the lubricating oil, resulting
in decreased viscosity of oil.
In case of liquid flow-back, remove the
cause(s).
If oil heater or devices on its control
circuit are defective, replace the
defective part.
Overheated operation
See the causes in item 02,
"Insufficient refrigerant flow".
Oil supply temperature is high.
See the causes in item 07, "Oil supply
temperature is high".
Machine is stopped for a
long time.
(No oil film on sliding
surfaces)
User-specific conditions, such
as intermittent heat load
If machine is sometimes stopped
longer than a week, take either of the
following measures: (i) Manually
operate oil pump alone and turn the
rotor shaft of the compressor.
(ii) Attach an oil pot for supply oil to
the seal cover.
Deteriorated part(s)
Hardened O-ring
If deteriorated over time, replace.
For other specific causes, see the
causes/action for symptom
"Overheating of sliding surface".
Swelled O-ring
* This occurs when the
lubricating oil of refrigerating
machine contains large
amount of refrigerant.
In case of liquid flow-back, remove the
cause(s).
If oil heater or devices on its control
circuit are defective, replace the
defective part.
Deteriorated seal ring/mating
ring
If deteriorated over time, replace.
For other specific causes, see the
causes/action for symptom
"Overheating of sliding surface".
Incompatibility of
lubricating oil and
operating conditions (such
as working temperature
range or refrigerant)
Unsuitable lubricating oil was
selected, or operating
conditions have changed after
installation of the equipment.
If possible, review the operating
conditions.
If not, see "4-1 Lubricating Oil
(Refrigerant Oil)" to select suitable
lubricating oil and replace the whole
quantity.
