12
Vacuum pump
P
V L VH
6.4 Copper pipe
6.4 Copper pipe
Low air pressure meter
(Gas side)
Instrument shunt
Fully tightened
3-way valve fully closed
(Liquid side)
Braze welding joint
Service port
Outdoor units
3-way valve fully closed
Fully tightened
Fully tightened
Braze welding joint
Braze welding joint
Indoor
Outdoor
Hight air pressure meter
Service port
It is advisable to use a high degree (Below 755mmHg) and larger capacity (Above 40L/minute) vacuum.
The time needed to purge air is relative to the length of piping, commonly 2-3 hours. Make sure 3-way valves of
gas and liquid side are closed.
If vacuum degree is less than -755mmHg after 2 hours, one more hour's purge could be taken.
But if vacuum degree is still less than -755mmHg after 3 hours' purge, leakage test is necessary to find out the leakage
point then repair it.
If vacuum degree reaches -755mmHg after more than 2 hours, close off the valves V
L
,V
H
of instrument shunt and
stop purging. After one hour, make sure no vacuum degree change exists. If there is a chance, it means leakage point
exists. Check and repair the leakage point.
After the above air purge, replace the vacuum pump with refrigerant pump to charge refrigerant.
No descend Passing
Pressure descends Check leaking point
Air purge
Installation Procedures
Connecting piping
When the temperature has a 1* difference, a variety of 0.01Mpa(0.1Kg/cm
2
g) will occur.
Modification is necessary when testing.
In condition of pressure descend when doing test step 1-3, check leakage at each joint by listening,
touching and using soap water to find out the leakage point. Weld or tighten the part union again.
Leakage point check
Test if pressure descends.
Use vacuum pump to purge air. It is absolutely forbidden to use refrigerant to purge air of the unit.
After air tightness teat, then purge nitrogen and close off the instrument shunt valve. Connect vacuum pump as shown
in Fig.
Air purge must be operated from gas and liquid sides.
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