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detection of air in refrigeration system and purging procedure

detection of air: high condensor pressure, small bubbles in sight glass, compressor discharge pressure high or running hot,More superheat, pressure fluctuations, in efficient working.  
Air puriging procedure
: during normal operation measure the temperature and pressure at the outlet of condensor, check the saturation temperature for the same pressure from the P-T chart of the refrigerant. compare the measured temperature with saturation and adjust the condensor cooling water flow( considering the sub cooling of the refrigerant also) for achieving near saturation conditions inside the condensor. with condensor outlet valve closed and cooling water
circulation on start the compressor and pump down the charge to the condensor with suction pressure not being dropped below atmospheric pressure(posibility of air ingress). circulate the water until both inlet and outlet temperatures are equal. compare outlet temperature (seawater) with refrigerant pressure in PT chart, if they dont match air is in the system, purge air opening the vent until temperature equals the saturation temperature for the given pressure.

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