8.1 SURVEY OF PERIODICAL INSPECTIONS ("CHECK LIST")
(Also refer to the explanation overleaf)
FREQUENCY
CHECK POINTS
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REMARKS
Oil level in crankcase
•
The oil level must be between 1 and 3 quarters
height of the sight glass. For topping up oil, refer to
Chapter 9, Compressor Maintenance.
Colour of the oil
•
The oil should be transparently clear. A disappearing
white colour points to dissolved refrigerant.
Lubricating oil pressure
•
The indication of the oil pressure gauge should be
1.5 bar higher than the value shown by the suction
pressure gauge.
Oil temperature
•
The maximum allowable temperature is 70 °C,
measured on the suction line to the oil suction filter.
Return from oil separator
•
To be checked only when a sight glass is provided in
the oil return line.
Oil leakage
•
Remedy visible oil leakage.
Suction pressure
•
Refer to plant manual.
Discharge pressure
•
Refer to plant manual. For the max. allowable
discharge pressure refer to Chapter 3, Technical data
of compressor.
Suction temperature
•
The suction temperature should indicate at least 5 K
superheat.
Discharge temperature
•
The maximum allowable discharge temperature is
170 °C.
Cooling water temperature (if
water cooling is applied)
•
Water temperature must be higher than condensing
temperature.
Crankcase heating (if provided)
•
During compressor standstill the crankcase bottom
side must remain warmer than the surroundings.
Condition of V-belts
•
Check belts for: 1) wear (fraying, cuts etc.) and
ensure that they do not touch the groove bottom; 2)
Tension. Too low a tension gives rise to excessive
flapping or oscillation in operation. For correct
tension consult the instructions given by the V-belt
supplier.
Adjustment and operation of pressure
safety switches
•
Refer to Chapter 7 and to the plant manual.
Switching frequency of the
compressor
•
The time interval between stopping and starting
should be at least 10 minutes.
Capacity control (if provided)
•
The time lag between the unloading and loading of
one cylinder or cylinder group should generally be at
least 3 minutes.
Number of operating hours
•
Check the number of operating hours in view of any
maintenance operations to be carried out.
Apart from the above check points, the sound produced by the compressor provides a proper standard
for its mechanical condition. If abnormal sounds are audible, their cause should be traced and removed
immediately in order to prevent serious breakdowns at inconvenient times.
Refrigeration Division
Grasso
8. PERIODICAL INSPECTION OF THE OPERATING COMPRESSOR
v002.97.10.en
Refrigeration Compressors Series RC9
Page 8.1
