OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 47
8. Use a vacuum pump to evacuate the unit /
cascade.
Warning!
Oil change intervals
Warning!
Change oil in SCUs using ammonia as
refrigerant after every 5,000 operating
hours or after 1 year at the latest.
Shut off oil pump!
Change oil in SCUs using ammonia as
refrigerant after every 10,000 operating
hours or after 2 year at the latest.
If evacuation is not possible, the unit / cascade is
vented in the next step via the vent valve on the
suction filter. Collect any escaping refrigerant
and dispose of in accordance with the legal
regulations.
4.6.6.2 Maintenance Work
Take oil samples for analysis and comparison of the
data with those of fresh oil at regular intervals.
Examine the colouration of the oil visually and
evaluate the degree of contamination.
9. The unit / cascade is pressurized with a slight
overpressure via the shut-off valve bypass check
valve discharge side.
10. Then check all components for leaks. If this has
been done, completely equalise pressure with
the pressure line and then check the
unit/cascade again for leaks. Charge oil and
startup the unit / cascade in accordance with the
Operating Instructions.
4.6.6.3 Changing the oil
1. The unit/ cascade must be run for at least half
an hour to reach the operating temperature
before the oil can be changed.
2. First shut down the unit/ cascade as described in
the Operating Instructions.
4.6.7 Replace oil filter
1. Switch off the unit / cascade.
3. Open the shut-off valve in the bypass line
around the check valve - suction side and the
suction-side shut-off valve to equalise the
pressure between unit / cascade and suction
line. If several units are operated in parallel, if
possible the refrigerant should be drawn off to
attain a pressure approx. 1 to 3 bar above
atmospheric pressure. Then reclose the shut-off
valves bypass and suction-side shut-off valve.
Otherwise the pressure can be reduced by
opening the vent valve on the suction filter and
then disposing of the refrigerant as specified by
law.
2. If the oil filter is very dirty it may be necessary to
replace it outside the normal maintenance
schedule.
3. To change the oil filter insert, close the following
valves in accordance with the P+I diagram and
the oil filter with multi-function block
documentation):
— (065) shut-off valves upstream of oil filter
— (070) shut-off valve function oil
— (080) Control valve - injection oil with
integrated check valve function
4. Then drain the waste oil via the oil draining/oil
charging valves and dispose of (Important!
hazardous waste!). Once this has been done,
reclose the valve and if possible continue to
draw off the refrigerant with a compressor
connected in parallel until atmospheric pressure
is virtually reached.
When closing the valve (080) note the
number of revolutions actuated. When
opening the valve it must be returned to its
initial position (see item 10). This is necessary
to ensure the final temperature remains
unchanged and therefore to avoid possible
vibrations in the oil line.
5. Otherwise depressurize the unit / cascade by
opening the vent valve - suction filter, taking
into account the safety regulations for
refrigeration systems.
— Shut-off valve bypass oil cooler (optional)
4. Equalise pressure with the atmospheric pressure.
5. Drain oil.
6. Open the drain plugs and valves on the oil
cooler, oil separator and oil filter with multi-
function block to drain any residual oil. Then
reclose the drain plugs and valves.
6. Dismantle oil filter cover of the multi-function
block.
7. Remove the oil filter element and properly
dispose of manner if it is highly soiled.
7. Replace the filter element of the oil filter and
clean or replace the filter insert of the suction
filter.
8. Carefully insert a new oil filter element.
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