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Start-up Leak Checking, Evacuation, and Charging
Leak Test
The suction shut-off valve and discharge shut-off valve on the compressor must remain closed during pressure testing to prevent air
and moisture from entering the compressor. The test pressure (dried nitrogen) must not exceed 20.5 bar, provided no other system
component’s pressure is lower. In this case, the lower pressure is the test pressure.
System Evacuation
Before the installation is put into commission, remove the holding charge then evacuate with a vacuum pump. Proper evacuation
reduces residual moisture to 50 ppm. The installation of adequately sized access valves at the furthest point from the compressor in the
suction and liquid lines is advisable. To achieve undisturbed operation, the compressor valves are closed and the system is evacuated
down to 0.3 mbar / 0.225 Torr. Pressure must be measured using a vacuum pressure (Torr) gauge on the access valves and not on the
vacuum pump. This serves to avoid incorrect measurements resulting from the pressure gradient along the connecting lines to the
pump. Then, the compressor must be evacuated.
Due to the factory holding charge of dry air, the compressor is under pressure (about 1 to 2.5 bar). This is to indicate the compressor
does not leak.
When plugs are removed from the compressor in order to connect a pressure gauge or to ll in oil, the plug may pop out under pressure
and oil can spurt out.
Preliminary Checks - Pre-starting
Discuss details of the installation with the installer. If possible, obtain drawings, wiring diagrams, etc. It is ideal to use a check-list but
always check the following:
• Visual check of the electrics, wiring, fuses etc.
• Visual check of the plant for leaks, loose ttings such as TVX bulbs, etc.
• Compressor oil level
• Calibration of HP and LP switches and any pressure actuated valves
• Check setting and operation of all safety features and protection devices
• All valves in the correct running position
• Pressure and compound gauges tted
• Correctly charged with refrigerant
• Compressor electrical isolator location and position
Charging Procedure
The system should be liquid-charged through the liquid-receiver shut-off valve or through a valve in the liquid line. The use of a lter drier
in the charging line is highly recommended. The majority of the charge should be placed in the high side of the system to prevent bearing
washout during rst-time start on the assembly line.
WARNING
Diesel effect! Compressor destruction! The mixture of air and oil at high temperature can lead to an explosion. Avoid operating
with air.
CAUTION
Low suction pressure operation! Compressor Damage! Do not operate with a restricted suction. Do not operate with the
low-pressure cut-out bridged.
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