Piper SARATOGA PA-32-301 Maintenance Manual page 129

COMPOUND GAGE
PULL 26 TO 28
PRESSURE GAGE
- NOTE -
For each 1,000 feet of elevation above sea level, the compound gauge
reading will be about one inch lower, numerically.
21-56-00
Page 21-23
Revised: August 11, 1983
1F9
PIPER AIRCRAFT
PA-32-301/301T
MAINTENANCE MANUAL
VACUUM
NOTE OPEN BOTH SERVICE VALVES
(COUNTERCLOCKWISE) ONE TURN
Figure 21-8. Evacuation Hookup
EVACUATING THE SYSTEM.
If the system has been operated in a discharged condition or anytime the system has been open to
atmospheric pressure. the recei er-dehydrator must be replaced and the system evacuated to remove any
trapped air and moisture which has entered it. A vacuum pump capable of pulling 29 inches of mercury or
better should be used. As we lower the pressure in the air conditioning system, we lower the boiling
temperature of the water (moisture) that may be present. Then we are able to pull this water, in the form of
vapor, out of the system. The following chart demonstrates the effectiveness of moisture removal under a given
vacuum
CHART 2106. SYSTEM VACUUM CHART I
System Vacuum
Temperature
F.
COMPOUND GAUGE
READING IN INCHES
OF MERCURY VACUUM
27.99
28.89
29.40
29.71
29.82
29.88
100
80
60
40
20
0