Blue Box - 90
12.3 REPAIRING THE REFRIGERANT CIRCUIT
If repairs have been made to the refrigerant circuit, perform the following steps:
- leak test;
- vacuum and dehydration of refrigerant circuit;
- refrigerant charge.
If the circuit is to be emptied, use the appropriate equipment to collect
the refrigerant.
12.3.1 Leak test
Charge the refrigerant circuit to a pressure of 15 bar with dry nitrogen gas by means of a cylinder fitted with a
pressure reducer. Check the circuit for leaks with a leak detector. The formation of bubbles or foam indicates the
presence of leaks.
If leaks are found during the test, empty the refrigerant circuit and then repair the point of leakage by welding
with appropriate alloys.
Do not use oxygen instead of nitrogen: explosion hazard.
12.3.2 High vacuum and dehydration of the refrigerant circuit
To generate a high vacuum in the refrigerant circuit use a high vacuum pump able to reach 0.1 mbar of absolute
pressure with a flow rate of 10 m3/h. With this type of pump, a single vacuum cycle is normally sufficient to reach
an absolute pressure of 0.1 mbar.
If this type of pump is not available, or in the event that the circuit has been left open for a long period of time,
you are strongly advised to use the triple evacuation method. This procedure is also prescribed in the event of
moisture in the refrigerant circuit.
Connect the vacuum pump to the charge connector.
Proceed as follows:
- Evacuate the circuit to a pressure of at least 35 mbar absolute. Charge the circuit with nitrogen to a relative
pressure of approx. 1 bar.
- Repeat the operation described above.
- Repeat the operation described above for the third time in order to reach the highest degree of vacuum possible.
This procedure should guarantee the elimination of up to 99% of contaminants.
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