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Installation Manual
NOTE
However, if the environmental temperature changes from the moment of applying pressure to 24 hours after that, the
pressure will change by about 0.01 MPa (0.1 kg / cm
2
G) per 1 °C. Consider the pressure change when checking the
test result.
REQUIREMENT
When pressure decrease is detected in steps 1-3, check the leakage at the connecting points.
Check the leakage using a foaming agent or other measures and seal the leak with re-brazing, flare retightening or
other methods. After sealing, execute an airtight test again.
Air purge
NOTE
For the air purge at installation time (Discharge of air in connecting pipes), use “Vacuum pump method” from
viewpoint of the protection of the earths environment.
• For protection of the earths environment, do not discharge the refrigerant gas in the air.
• Eliminate the remaining air (nitrogen gas, etc.) in the unit by using a vacuum pump.
If gas remains, performance and reliability of the unit may be reduced.
After the airtight test, discharge nitrogen gas. Then connect the gauge manifold to the service ports at gas side and
liquid side, and connect the vacuum pump as shown in the following figure.
Perform vacuuming for gas side and liquid side.
• Perform vacuuming from both liquid and gas sides.
• 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 -755 mmHg) and a large exhaust gas amount (over 40 L /
minute).
• Perform vacuuming for 2 or 3 hours though time differs due to pipe length.
In this time, check all valves at liquid and gas sides are fully closed.
• If vacuuming valve amount is not decreased to below -755 mmHg even after vacuuming for 2 hours or more,
continue vacuuming for 1 hour or more.
If -755 mmHg or less cannot be obtained by 3 hours or more vacuuming, detect and repair the leak.
• When the vacuuming valve has reached -755 mmHg 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.
Main pipe
Connected to indoor unit
Low pressure
guage
High pressure
guage
Ball valve fully closed
(Gas side)
Flare connection
Flare connection
Packed valve fully closed
(Liquid side)
Service port
Vacuum pump
Gauge
manifold
Outdoor unit
Service port
EN-37
EN-38
1FAN_IM_DHV0100301-00_EN.book Page 19 Saturday, November 4, 2017 2:39 PM
