19
8.9 Vacuum process
WARNING
● For protection of the earths environment, do not discharge the refrigerant gas in the air.
● Using a vacuum pump, eliminate the remaining air (nitrogen gas, etc.) in the unit. If gas remains, performance
and reliability of the unit may be reduced.
After the leakage test, discharge nitrogen gas. Then connect the gauge manifold to the service ports at suction
gas side, discharge gas side and liquid side, and connect the vacuum pump as shown in the following figure.
Be sure to perform vacuuming for suction gas side, discharge gas side and liquid side.
● Be sure to perform vacuuming from both suction gas side, discharge gas side and liquid side.
● Be sure to perform vacuuming from both liquid and gas sides at the same time.
● Use a vacuum pump with counter-flow preventive function so that oil in the pump does not back up in the
pipe of the air conditioner when the pump has been stopped. (If oil in the vacuum pump enters in to the air
conditioner with R410A refrigerant, an error may occur in the refrigeration cycle.)
● Use a vacuum pump that has a high vacuum (below -755mmHg) and a large exhaust gas amount (over 40L/
minute).
● Perform vacuuming for 2 or 3 hours though time differs due to pipe length. In this time, check all packed valves
at liquid, gas and balance sides are fully closed.
● If vacuuming valve amount is not decreased to below -755mmHg even after vacuuming for 2 hours or more,
continue vacuuming for 1 hour or more. If -755mmHg or less cannot be obtained by 3 hours or more vacuuming,
detect and repair the leak.
● When the vacuuming valve has reached -755mmHg or less after vacuuming for 2 hours or more, close valves
VL and VH on the gauge manifold fully. Stop the vacuum pump, leave it as it is for 1 hour and then check the
vacuum does not change. If it does change then there may be a leak within the system.
● After the above procedure for vacuuming has finished, exchange the vacuum pump with a refrigerant cylinder
and advance to the additional charging of refrigerant.
Chart
28
8 refrIGerANT pIpING
