Vacuum Testing; Table 2 - System Pressures - York R-134a Operation And Maintenance Manual

SECTION 6 - MAINTENANCE

TABLE 2 - SYSTEM PRESSURES

*GAUGE
INCHES OF
MERCURY (HG)
BELOW ONE
STANDARD
ATMOSPHERE
0
10.24"
22.05"
25.98"
27.95"
28.94"
29.53"
29.67"
29.72"
29.842"
29.882"
29.901"
29.917"
29.919"
29.9206"
29.921"
NOTES: *One standard atmosphere = 14.696 PSIA
3. Test around each joint and factory weld. It is im-
portant that this test be thoroughly and carefully
done, spending as much time as necessary and us-
ing a good leak detector.
4. To check for refrigerant leaks in the evaporator
and condenser, open the vents in the evaporator
and condenser heads and test for the presence of
refrigerant. If no refrigerant is present, the tubes
and tube sheets may be considered tight. If refrig-
erant is detected at the vents, the heads must be
removed, the leak located (by means of soap test
or leak detector) and repaired.

VACUUM TESTING

After the pressure test has been completed, the vacuum
test should be conducted as follows:
1. Connect a high capacity vacuum pump, with in-
dicator, to the system charging valve as shown in
Figure 11 on page 23 and start the pump. (See
Vacuum Dehydration on page 25.)
24
ABSOLUTE
MILLIMETERS OF
PSIA
MERCURY (HG)
14.696 760.
9.629 500.
3.865 200.
1.935 100.
.968 50.
.481 25.
.192 10.
.122 6.3
.099 5.
.039 2.
.019 1.0
.010 .5
.002 .1
.001 .05
.0002 .01
0 0
= 760 mm Hg. absolute pressure at 32°F
= 29.921 inches Hg. absolute at 32°F
BOILING
TEMPERATURES
OF
MICRONS
WATER
°F
760,000 212
500,000 192
200,000 151
100,000 124
50,000 101
25,000 78
10,000 52
6,300 40
5,000 35
2,000 15
1,000 +1
500 –11
100 –38
50 –50
10 –70
0
PSIG = lb. per sq. in. gauge pressure
= Pressure above atmosphere
PSIA = lb. per sq. in. absolute pressure
= Sum of gauge plus atmospheric pressure
2. Open wide all system valves. Be sure that all
valves to the atmosphere are closed.
3. Operate the vacuum pump in accordance with
VACUUM DEHYDRATION until a wet bulb
temperature of +32°F (0°C) or a pressure of 5 mm
Hg is reached. See Table 2 on page 24 for cor-
responding values of pressure.
4. To improve evacuation circulate hot water (not
to exceed 125°F, 51.7ºC) through the evaporator
and condenser tubes to thoroughly dehydrate the
shells. If a source of hot water is not readily avail-
able, a portable water heater should be employed.
DO NOT USE STEAM. A suggested method is
to connect a hose between the source of hot water
under pressure and the evaporator head drain con-
nection, out the evaporator vent connection, into
the condenser head drain and out the condenser
vent. To avoid the possibility of causing leaks, the
temperature should be brought up slowly so that
the tubes and shell are heated evenly.
FORM 160.76-O1
ISSUE DATE: 05/22/2019
WATER
FREEZES
JOHNSON CONTROLS