condensor,evaporative condenser and water cooled condenser

To determine whether it is necessary to purge the plant,the refrigeration plant must be stopped until all components in the system have reached the same temperature.
The proceed as follows :

1. Stop the compressor,for at least two hours.
2. Close the compressor suction stop valve and any valves between the condenser and receiver.
3. Loosen the pressure gauge in order to check it.
4. Start the cooling pump.After a short time,measure the temperature of the cooling water,which should then be compared with the reading onthe pressure gauge.If the pressure gauge shows a higher pressure than that which corresponds to the cooling water temperature,non condensable gases are present in the condenser.
5. The gases should be purged from the top of the condenser by carefully opening the purging valve or perhaps loosening a screwed connection or something similiar.
6. Repeat the purging process a few more times,at intervals of 3-4 minutes during which the cooling water should run continuously as any water valves which may be installed can otherwise become blocked in open position.
7. If purging is constantly required,please check the plant for leaks.