Allied Air 4SHP13 series Installation Instructions Manual page 11

4. Connect a cylinder of nitrogen with a pressure regulating
valve to the center port of the manifold gauge set. When
using high pressure gas such as nitrogen for this
purpose, be sure to use a regulator that can control
the pressure down to 1 or 2 psig.
5. Adjust nitrogen pressure to 150 psig. Open the valve
on the high side of the manifold gauge set to pressurize
the line set and the indoor coil.
6. After a short period of time, open a refrigerant port to
make sure that an adequate amount of refrigerant has
been added for detection (refrigerant requirements will
vary with lengths). Check all joints for leaks. Purge
nitrogen and R410A mixture. Correct any leaks and
recheck.
Fire, Explosion, and Personal Safety Hazard.
Failure to follow this warning could result in damage,
personal injury, or death.
Never use oxygen to pressurize or purge refrigeration
lines. Oxygen, when exposed to a spark or open flame,
can cause damage by fire and/or an explosion, that could
result in personal injury or death.
Evacuation
Evacuating the system of noncondensables is critical for
proper operation of the unit. Noncondensables are defined
as any gas that will not condense under temperatures and
pressures present during operation of an air conditioning
system. Noncondensables and water vapor combine with
refrigerant to produce substances that corrode copper piping
and compressor parts.
Do not use a compressor to evacuate a system. Avoid
deep vacuum operation. Extremely low vacuums can
cause internal arcing and compressor failure. Danger
of equipment damage. Damage caused by deep
vacuum operation will void warranty.
Use a thermocouple or thermistor electronic vacuum gauge
that is calibrated in microns. Use an instrument that reads
down to 50 microns.
1. Connect the manifold gauge set to the service valve
ports as follows:
• Low pressure gauge to suction line service valve
• High pressure gauge to liquid line service valve
506762-01
WARNING
WARNING
2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to the
center port of the manifold gauge set.
4. Open both manifold valves and start vacuum pump.
5. Evacuate the line set and indoor unit to a minimum of 500
microns or lower. During the early stages of evacuation, it is
desirable to close the manifold gauge valve at least once to
determine if there is a rapid rise in pressure. A rapid rise in
pressure indicates a relatively large leak. If this occurs, the
leak testing procedure must be repeated.
6. When 500 microns or lower is maintained, close the
manifold gauge valves, turn off the vacuum pump, and
disconnect the manifold gauge center port hose from the
vacuum pump. Attach the manifold gauge center port
hose to a nitrogen cylinder with pressure regulator set to
150 psig and purge the hose. Open the manifold gauge
valves to break the vacuum in the line set and indoor unit.
Close the manifold gauge valves.
7. Shut off the nitrogen cylinder and remove the manifold
gauge hose from the cylinder. Open the manifold gauge
valves to release the nitrogen from the line set and indoor
unit.
8. Reconnect the manifold gauge to the vacuum pump,
turn the pump on, and continue to evacuate the line set
and indoor unit until 500 microns is maintained within a
20-minute period after shutting off the vacuum pump
and closing the manifold gauge valves.
9. When the requirements above have been met,
disconnect the manifold hose from the vacuum pump.
Open the service valves to break the vacuum in the line
set and indoor unit.
Issue 1143 Page 11 of 24