B5 EVACUATION OF THE COMPRESSOR
To evacuate the refrigeration system refer to §A2.2.
Procedure to evacuate the compressor:
a) Close the suction stop valve and the stop valve in
the oil return line of the oil separator.
b) Check that the discharge stop valve is open.
c) Set suction pressure safety switch to 0.3 bar(a).
d) Start the compressor (manual).
e) Wait until the compressor will be cut out of
operation either by the min. suction pressure safety
switch [min Psuc] or the min. oil differential
pressure safety switch [dOil].
Do not start the compressor again, but close the
discharge stop valve as soon as possible.
Be sure the compressor will not start again!
g) Remove the remainder of the refrigerant, via the
evacuation/purging valve(s) as prescribed by local
safety regulations. For the location of these valves
refer to the "Engineering Data".
h) Reset the suction pressure safety switch [Psuc].
B6 DRAINING AND CHANGE OF OIL
To top up oil see § B4.1.
Oil changing procedure:
a) Evacuate the compressor (refer to §B5).
b) Drain the oil via the oil charging/drain valve.
Remove the cover of one or more service openings
on the compressor side.
c) Clean the inside of the crankcase with a non-fibrous
cloth (do not use cotton waste!).
d) Replace the service cover(s) with a new gasket.
e) Charge crankcase with clean or fresh oil in
accordance with the procedure of §A2.3.
B7 CLEANING OF OIL FILTERS
In most cases the oil filters have to be cleaned for
the first time after 100 operating hours. Besides
thorough cleaning of the strainer element of the
oil suction filter, the paper filter element of the oil
discharge filter should be renewed. Also after the
installation has been extended or modified, the
filters should be cleaned as if the compressor had
just been put in operation. The time at which the
next cleaning has to be carried out highly depends
on the cleanliness of the installation.
Small impurities in the refrigerant gas that are not
retained by the suction strainer eventually find
their way in the lubricating oil and may cause
clogging of the oil suction filter. A strong pollution
of this filter is indicated by a falling oil pressure; in
this case it is necessary to clean the filter. It is
recommended, therefore, regularly to check the
oil pressure during the first 100 operating hours.
When the filters remain practically clean, cleaning
can take place simultaneously with the other
maintenance operations.
The oil filters can be cleaned as follows:
a) Drain the oil via the oil charging valve.
b) Purge the compressor (refer to par. B5)
c) Remove the discharge filter housing and the
released paper filter element. Catch up the
remaining oil present in this housing. After draining
the oil out of the crankcase, remove one of the side
covers and remove the gauze filter element by
unscrewing it from the internal suction pipe.
d) Clean the gauze filter element of the oil suction
filter in a receptacle containing oil or a solvent.
After cleaning, thoroughly dry the element; if
possible, blow through the filter element with
compressed air against the normal oil flow direction.
e) Clean the discharge filter housing and dry it with a
non-fibrous cloth.
f) Refit the gauze filter element and place a new filter
element.
g) Fit the discharge filter housing against the
crankcase (do not forget the gasket); also check
that the filter element is perfectly fit.
h) Remove the plug on top of the shaft seal housing;
fill this housing with fresh oil and replace the plug.
j) Purge the compressor (refer to par. B10)
k) Check oil level and top up oil as per par. B4.1.
Refrigeration Division
Grasso
B: INSPECTION, MAINTENANCE
AND TROUBLE SHOOTING
v001.99.01.en Installation and Maintenance Manual RC(U)6 B1.5
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