Charging and commissioning
Step-by-step
1.
Ensure that there is no power supply to the unit. Hence, it is acceptable to
leave the crankcase heater off.
2.
Connect the refrigerant cylinder to main service hose and purge line at the
manifold end.
3.
Invert the refrigerant cylinder if necessary to ensure only liquid refrigerant can be
charged into the system. This will be charged through the high pressure side of the
manifold and liquid service valve.
4.
The refrigerant cylinder should be weighed at this point to be able to record the
final refrigerant charge.
5.
Now open the liquid service valve (off the back seat). In warm ambient, with a
good vacuum in the system and the refrigerant cylinder inverted, it may not be
necessary to run the compressor.
6.
In cooler ambient, it may be necessary to run the compressor in order to complete
charging. Stream compressor systems should be charged as quickly as possible by
bleeding liquid refrigerant into the suction line with the compressor running.
7.
The system needs to be operated down to its set point before you can be sure that
the charge is correct. It is at this point that the normal refrigeration operational
checks can be carried out—such as checking the liquid line sight glass for bubbles
and the operating pressures.
8.
If the system is still short of the refrigerant, bleed liquid refrigerant into the suction
side with the compressor running.
9.
Check the oil level and add oil if necessary.
Oil charging
a.
Check the oil level of compressor viewing the oil
level controls oil sight glass.
b.
Pump additional oil into the compressor to a
maximum ½ sight glass level.
Unit Operation
Before starting the unit, ensure the following:
a.
All the electrical connections are correct and as per the recommended wiring
diagrams.
b.
All low side tubing is properly insulated.
c.
Leak check is completed and unit is pre-charged with refrigerant through high
side.
d.
Check for superheat setting on the expansion valve (TXV) appropriate or not.
Adding refrigerant on a cold weather results to an overcharged unit, which may then trip
out on high pressure limit during warm weather.
Suction Superheat should be 10–15 K for reliable operation.
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