We have just installed a refrigeration plant with copper pipe lines. The plant after installation was tested for leakage by putting Nitrogen at 300 psi and the same was retained for 48 hours. There was no leakages nor any pressure drops. All the joints were tested with soap water

After about a month it was found that there was a shortage of refrigerant in the system. Again before filling the system with R 22 refrigerant we tested for leakage with Nitrogen. After 2 days of proper working again there was a shortge of leakage. I personally visited the site and had both the sides ie. the high side and the low side tested seperately with lekage with Nitrogen at 300 psi. Kept the pressure overnight. There was no leakage. Charged the system with refrigerant and the plant operated absolutely fine for two days. Now again there is shortage of refrigerant and the temperature is not being attained.

The compressors are semi hermetic of a renowned make, the Evaporators are also of renowned make.

The unit is to maintain a temperature of - 35 Deg C inside the room which it is performing so long there is no leakage of refrigerant.

Could some one advice me and guide me as to what other tests could be carried out so as to detect the leakages. Should the pressure of Nitrogen be increased and if so to what extent so as not to damage any component.

Please advice soon It is not possible to shut down the plant for a long time, as this is an Ice Cream Hardening Room.