XTEMP ENVIRONMENTS (SHANGHAI) CO., LTD.
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Chapter 4 Maintenance
4
Fig 43 Checking and charging of the refrigerant
If suction pressure during deep cooling is lower than rated, this is indication of serious
leakage refrigerating system, usually meaning a cracked joint or damaged connection or,
blockage of the capillary tube or filter drier. Test the refrigerating system for leakage or
blockage location by using of Nitrogen:
Connect the charging hosing to Nitrogen source of 99.99% purity to a pressure of 10 bar.
Keep the pressure for at least 2 h and record the pressure change during the period.
Note the effect of ambient temperature on pressure fluctuation.
Spy the leakage source by using of soap water or equivalent. The leakage usually
happens at joint of brazing, but sometimes seal of a schrader valve or refrigerating
component.
Braze the joint where leakage occurred or replace the leakage part and component.
Evacuate the system for at least 2 h. Use the same refrigerant, quantity and type, as
indicated in the name plate.
If pressure of refrigerant is no less than atmosphere, the higher the pressure, the less the
extent of potential leakage. Flush the hosing and compound gauge by internal residual
refrigerant. Charge the same refrigerant to a pressure resulting in rated cooling capacity.
For locating of blockage of the system, the high and low pressure side have to be
separated.
