Air Purging; Outdoor Unit - Panasonic U-72MF2U9 Technical Data Manual

7. AIR PURGING

7. 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
1
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
2
the test run has been completed.
Remove the valve caps from all service ports on the

outdoor unit.

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
3
outdoor unit is installed.
Leak test
(1) Attach a manifold valve (with pressure gauges) and
dry nitrogen gas cylinder to all service ports with
4
charge hoses.
The balance tube leak test is not necessary if only 1
outdoor unit is installed.
CAUTION
5
6 (2) Pressurize the system to no more than 484 psig
(3.34 MPa) {33.1 k
and close the cylinder valve when the gauge reading
reaches 484 psig (3.34 MPa) {33.1 kgf/cm
test for leaks with liquid soap.
7
CAUTION
8
9
Use a manifold valve for air
purging. If it is not available,
use a stop valve for this
purpose. The "Lo" knob of the
manifold valve must always
be kept closed.
2
g f/cm G} with dry nitrogen gas
2
G}. Then,
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
ex.)Type 72
Service port cap
Flare nut
Flare nut
Manifold valve
Pressure
Lo
gauge
Cylinder
valve
Open
Suction
tube
Open
Discharge
tube
Open
Liquid
tube
Open
Balance
tube
37
2 - 42
Design of 3WAY VRF SYSTEM
Vacuum pump
Outlet
Valve cap
Service port cap
Hi
Charge hose
Nitrogen gas cylinder
(In vertical standing
position)
Close
Outdoor unit
Close
Close
Close
Inlet