Johnson Controls York MaxE YK Series, Manual

Page: 124 / 139

FORM 160.75-O1 (309)
25
JOHNSON CONTROLS
6
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 indica-
tor, to the system charging valve as shown in FIG. 9
and start the pump. (See “Vacuum Dehydration”.)
2. Open wide all system valves. Be sure 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 or a pressure of 5 mm Hg is
reached. See Table 2 for corresponding 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 available, 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 pres-
sure and the evaporator head drain connection, 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.
5. Close the system charging valve and the stop valve
between the vacuum indicator and the vacuum pump.
Then disconnect the vacuum pump leaving the vac-
uum indicator in place.
6. Hold the vacuum obtained in Step 3 in the system for
8 hours; the slightest rise in pressure indicates a leak
or the presence of moisture, or both. If, after 24 hours
the wet bulb temperature in the vacuum indicator has
not risen above 40°F (4.4°C) or a pressure of 6.3 mm
Hg, the system may be considered tight.
Be sure the vacuum indicator is valved
off while holding the system vacuum
and be sure to open the valve between
the vacuum indicator and the system
when checking the vacuum after the
8 hour period.
7. If the vacuum does not hold for 8 hours within the
limits specified in Step 6 above, the leak must be
found and repaired.
taBle 2 – SYSTEM PRESSuRES
*gAugE ABSOLuTE
BOILINg
INCHES OF TEMPERATuRES
MERCuRY (Hg) MILLIMETERS OF
BELOw ONE PSIA OF MERCuRY MICRONS wATER
STANDARD (Hg) °F
ATMOSPHERE
0 14.696 760. 760,000 212
10.24" 9.629 500. 500,000 192
22.05" 3.865 200. 200,000 151
25.98" 1.935 100. 100,000 124
27.95" .968 50. 50,000 101
28.94" .481 25. 25,000 78
29.53" .192 10. 10,000 52
29.67" .122 6.3 6,300 40
29.72" .099 5. 5,000 35
29.842" .039 2. 2,000 15
29.882" .019 1.0 1,000 +1
29.901" .010 .5 500 –11
29.917" .002 .1 100 –38
29.919" .001 .05 50 –50
29.9206" .0002 .01 10 –70
29.921" 0 0 0
*One standard atmosphere = 14.696 PSIA
= 760 mm Hg. absolute pressure at 32°F
= 29.921 inches Hg. absolute at 32°F
NOTES: PSIA = Lbs. per sq. in. gauge pressure
= Pressure above atmosphere
PSIA = Lbs. per sq. in. absolute pressure
= Sum of gauge plus atmospheric pressure