Purging of air from the refrigeration system

When there is steady increase in  high pressure gauge reading, which gives a indication that the air is present in the system. 

The effective area of condenser available for condensing refrigerant will be reduced due to accumulation of air.

so we need to purge the air out,

• Close the condenser outlet liquid valve and compressor will trip on L.P cut off. sea water is left circulating in the condenser for few hours to achieve equilibrium.
• Now, note the HP gauge reading. If no air present in the condenser, there will be no change in the reading. If air is present, then the reading will be higher yhan the previous value.

The refrigerant will condense and collect in the receiver but air stratifies and collect on top of the refrigeration liquid. Now crack open the vent cock to purge out air from the system.