08: Leak From Mechanical Seal - mycom 3225**C Series Instruction Manual

08: Leak from mechanical seal

Direct cause
Initial leak after
replacement until sliding
surfaces settle
Sliding surface is
roughened due to
overheating.
Machine is stopped for a
long time.
(No oil film on sliding
surfaces)
Deteriorated part(s)
Incompatibility of
lubricating oil and
operating conditions (such
as working temperature
range or refrigerant)
Compound 2-stage Screw Compressor 3225**C
Root cause
In some cases, immediately
after replacement, the
compressor-specific operating
conditions and the pressure
receiving conditions of
machined sliding surface is
unstable.
Started and stopped too many
times.
* In case of standard
equipment, "four or more
times per hour" is considered
"frequent/too many".
Excessive refrigerant solved
into the lubricating oil, resulting
in decreased viscosity of oil.
Overheated operation
Oil supply temperature is high.
User-specific conditions, such
as intermittent heat load
Hardened O-ring
Swelled O-ring
* This occurs when the
lubricating oil of refrigerating
machine contains large
amount of refrigerant.
Deteriorated seal ring/mating
ring
Unsuitable lubricating oil was
selected, or operating
conditions have changed after
installation of the equipment.
6-6
2202MYJE-MY-C8-N_2018.02.
Chapter 6 Troubleshooting
Action
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.
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.
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.
See the causes in item 02,
"Insufficient refrigerant flow".
See the causes in item 07, "Oil supply
temperature is high".
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.
If deteriorated over time, replace.
For other specific causes, see the
causes/action for symptom
"Overheating of sliding surface".
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.
If deteriorated over time, replace.
For other specific causes, see the
causes/action for symptom
"Overheating of sliding surface".
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.