TM 5-3810-307-24-1-2
Purging Non-Condensable Gases (Air)
During purging and refrigerant recovery air can be entrapped in the
refrigerant container. Air must not be put into an AC system. The result is
higher operating pressures and possible system damage.
A simple check can be performed as follows:
1. Store the recovered refrigerant at constant temperatures
above 650 deg. F (18.7C). The container should include a pressure
gauge reading to 1 psi increments. The container should not
be in direct sunlight or near a heat source.
2. Use a calibrated thermometer to establish temperature
within 4 inches of the container.
3. Compare the pressures for like temperatures in Figure 9-2.
If the container pressure is equal to or less than the pressure
shown in the table, excess air is not present.
4. If container pressure is greater than shown in the table,
connect the container to recovery or recycle equipment with
the pressure gauge in place.
5. Bleed a small amount of vapor from the container until the
pressure is below that shown on the table, then close the
valve.
6. Tank temperature may change during the bleed off process.
Mild shaking will assist in temperature stabilizing, but it is a
good idea to let it set for several hours before again checking
pressure against the table.
7. If the pressure remains above that shown on the table, excess
air or another contaminant (i.e., another refrigerant) is still
present. This material must be recycled or reclaimed.
8. If the pressure is equal or below that shown on the table
identify the cylinder as "recycled."
