Air Purging By Using Vacuum Pump - Hitachi RAM-90NP5B Service Manual

4. Air purging by using vacuum pump

Remove the valve cap from the service valves located at both the
large and small pipe rims
Connect the charging hose A to the large service valve.
After connecting the vacuum suction pump adaptor, connect the
charging hose B to the adaptor.
During relocation or re-installed, there is a possibility of electric-
powered valve to be closed. Should the electric-powered valve be
closed, even with air purging being conducted, certain amount of air
is still trapped within that area, hence, there is a need to open up the
electric-powered valve to do an air purging. Under such circumstances,
before using the vacuum-suction pump, the main power supply (LN
terminal) should be connected to enable a complete opening up of
the valve. After connecting the power supply for approximately 90
seconds, the valve will be fully opened, after which disconnect the
power supply and start using the vacuum suction pump.
(Refer to "Power Supply Terminal Connections" in regards to the LN
terminal)
CAUTION: Ingress of air during the operating cycle may cause increase
in pressure and other breakdowns.
Switch off the outdoor unit's power supply
Shut the manifold valve handle Hi, handle Lo need to be open and
operate the vacuum pump for approximately 60 minutes.
Upon a full shut of manifold valve handle Lo, the vacuum pump can
be stopped.
Check to ensure that there is no gas leakage.
After removing the charging hose A, rotate the service valve spindles
in an anti-clockwise direction to fully open for both valves.
Reinstall the cap nuts to their original positions and tighten them to
their specifi ed torque.
Disconnect the charge hose from the service valve.
Tighten the valve cap of valve core.
[Torque 12.3 - 15.7 N·m (125 - 160 kgf·cm)]
Fix the valve cap to the spindles of each large and small dia. pipe
side service valves.
Tighten the valve cap of the spindle.
[Torque 19.6 - 24.5 N·m (200 - 250 kgf·cm)]
CAUTION
!
1. Be sure to use the vacuum pump, vacuum pump adapter and manifold gauge and refer to their instruction manuals beforehand.
2. Ascertain that the vacuum pump is fi lled with oil to the level designated on the oil gauge.
3. After closed the ball valve of charge hose, it should be disconnected at service port side and refrigerant cylinder side at fi rst.
Next, after discharging the remained gas in the charge hose by opening the ball valve a little, disconnect it at manifold gauge side.
You can prevent sudden release of refrigerant by connecting the ball valve to service port. And you can work more safety.
– 15 –
Fig. 6-1
Fig. 6-2
Fig. 6-3