U-Match Series Duct Type Unit
23
3.2.4 Connection Pipe Vacuum Pumping
NOTICE
Make sure the outlet of vacuum pump is away from fire source and is well-
ventilated.
(1) Remove the caps of the liquid valve, gas valve and also the service port.
(2) Connect the hose at the low pressure side of the manifold valve assembly to
the service port of the unit’s gas valve, and meanwhile the gas and liquid valves
should be kept closed in case of refrigerant leak.
(3) Connect the hose used for evacuation to the vacuum pump.
(4) Open the switch at the lower pressure side of the manifold valve assembly and
start the vacuum pump. Meanwhile, the switch at the high pressure side of the
manifold valve assembly should be kept closed, otherwise evacuation would
fail.
(5) The evacuation duration depends on the unit’s capacity, generally.
GU85W/A1-K
30
GU140W/A1-M
45
And verify if the pressure gauge at the low pressure side of the manifold valve
assembly reads -0.1MPa (-75cmHg), if not, it indicates there is leak somewhere.
Then, close the switch fully and then stop the vacuum pump.
(6) Wait for 10min to see if the system pressure can remain unchanged. If the
pressure decrease, there may be leakage.
(7) Slightly open the liquid valve and let some refrigerant go to the connection pipe
to balance the pressure inside and outside of the connection pipe, so that air
will not come into the connection pipe when removing the hose. Note that the
gas and liquid valve can be opened fully only after the manifold valve assembly
is removed.
(8) Place back the caps of the liquid valve, gas valve and also the service port.
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