3 Piping work and refrigerant charge
Refrigerant charge
SMGB0091 rev.2 - 11/2015
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3.4.2 Refrigerant charge procedure
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C A U T I O N
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Use refrigerant R410A in the refrigerant cycle. Do not charge oxygen, acetylene or other flammable and poisonous gases into the
refrigerant cycle when performing a leakage test or an air-tight test.
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These types of gases are extremely dangerous and can cause an explosion. It is recommended that compressed air, nitrogen or
refrigerant be used for these types of tests.
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Check to ensure that no pressure exists inside the stop valve before removing the flange.
Vacuum procedure and refrigerant charge
Evacuation and refrigerant charging procedure should be performed according to the following instructions.
• The stop valve has been closed before shipment. However, make sure that the stop valves are completely closed.
• Connect the gauge manifold using charging hoses with a vacuum pump or a nitrogen cylinder to the check joints of
the liquid line and the gas line stop valve.
•
Check for any gas leakage at the flare nut connection, by using nitrogen gas to increase the pressure at 4.15 MPa
inside of the field-supplied piping.
• Operate the vacuum pump for 1 to 2 hours until the pressure decreases lower than a pressure of 756 mmHg in
vacuum.
• For charging refrigerant, connect the gauge manifold using charging hoses with a refrigerant charging cylinder to the
check joint of the liquid line stop valve.
• Charge the proper quantity of refrigerant according to the piping length (Calculate the quantity of the refrigerant
charge).
• Fully open the gas line stop valve, and slightly open the liquid line stop valve.
• Charge refrigerant by opening the gauge manifold valve.
• Charge the required refrigerant within the difference range of ±0.5kg by operating the system in cooling.
• Fully open the liquid line stop valve after completing refrigerant charge.
• Continue cooling operation for more than 10 minutes to circulate the refrigerant.
• Remove the “close” plate from the stop valve and hook the attached “open” plate at the stop valve.
Liquid line
Gas line
Liquid stop valve
Nitrogen tank
(For air Tight test & Nitrogen
blow during brazing)
Vacuum cylinder
Manifold
gauge
Gas stop valve
Example of Evacuation and Refrigerant Charge for RASC unit.
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N O T E
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Charge the refrigerant correctly. Overcharge and insufficient charge of the refrigerant may cause the compressor failure.
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Insulate the unions and flare-nuts at the piping connection part completely.
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Insulate the liquid pipe for prevention of the capacity decrease according to the ambient air conditions and the dewing on the pipe
surface by the low pressure.
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Check to ensure that there is no gas leakage. When large amount of the refrigerant leaks, the troubles as follows may occur:
- Oxygen deficiency
- Harmful gas generation due to chemical reaction with fire.
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Use thick gloves to protect your hands from liquid refrigerant injuries when handling refrigerant.