Air Purging; Air Purging With A Vacuum Pump (For Test Run; Preparation - Panasonic U-72MF1U9 Installation Instructions Manual

6. AIR PURGING

Air and moisture in the refrigerant system may have
undesirable effects as indicated below.
●
pressure in the system rises
●
operating current rises
●
cooling (or heating) efficiency drops
●
moisture in the refrigerant circuit may freeze and
block capillary tubing
●
water may lead to corrosion of parts in the refrigerant
system
Therefore, the indoor unit and tubing between the
indoor and outdoor unit must be leak tested and
evacuated to remove any noncondensables and
moisture from the system.

■ Air Purging with a Vacuum Pump (for Test Run)

Preparation

Check that each tube between the indoor and outdoor
units have been properly connected and all wiring for
the test run has been completed. Remove the valve
caps from all service ports on the outdoor unit. (Fig.
6-2) Note that all service valves on the outdoor unit are
kept closed at this stage.
The balance tube leak test is not necessary if only 1
outdoor unit is installed.
Leak test
(1) Attach a manifold valve (with pressure gauges) and
dry nitrogen gas cylinder to all service ports with
charge hoses.
The balance tube leak test is not necessary if only 1
outdoor unit is installed.
Use a manifold valve for air
purging. If it is not available,
CAUTION
use a stop valve for this
purpose. The "Hi" knob of
the manifold valve must
always be kept closed.
(2) Pressurize the system to no more than 512 psig
(36 kgf/cm G) with dry nitrogen gas and close the
2
cylinder valve when the gauge reading reaches
512 psig (36 kgf/cm G). Then, test for leaks with
2
liquid soap.
To avoid nitrogen entering the
CAUTION
refrigerant system in a liquid
state, the top of the cylinder
must be higher than the
bottom when you pressurize
the system. Usually, the
cylinder is used in a vertical
standing position.
Manifold gauge
Fig. 6-1a
Valve cap
Flare nut
Fig. 6-2
Manifold valve
Pressure
Lo Hi
gauge
Cylinder
valve
Open
Suction
tube
Open
Discharge
tube
Open
Liquid
tube
Open
Balance
tube
Fig. 6-3
36
Vacuum pump
Outlet
Inlet
Fig. 6-1b
Service port cap
Charge hose
Nitrogen gas cylinder
(In vertical standing
position)
Close
Outdoor unit
Close
Close
Close