Air Purging - Panasonic U-72MF1U9 Technical Data Manual

6. AIR PURGING

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
1
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. 2-30) Note
2
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
3
(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
4
outdoor unit is installed.
CAUTION
5
(2) Pressurize the system to no more than 512 psig
6
(36 kgf/cm 2 G) with dry nitrogen gas and close the
cylinder valve when the gauge reading reaches
512 psig (36 kgf/cm
liquid soap.
7
CAUTION
8
Use a manifold valve for air
purging. If it is not available,
use a stop valve for this
purpose. The "Hi" knob of
the manifold valve must
always be kept closed.
2 G). Then, test for leaks with
To avoid nitrogen entering the
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. 2-29a
Flare nut
Pressure
gauge
Suction
tube
Discharge
tube
Liquid
tube
Balance
tube
2 - 44
Design of 3WAY VRF SYSTEM
Vacuum pump
Fig. 2-29b
Valve cap
Service port cap
Fig. 2-30
Manifold valve
Lo Hi
Charge hose
Cylinder
valve
Nitrogen gas cylinder
(In vertical standing
position)
Open
Close
Open
Outdoor unit
Close
Open
Close
Open
Close
Fig. 2-31
Outlet
Inlet