Carrier 19DA - Manual (Page 2)

PURGE VALVE OPERATION PLATE
PURGE PUMP
SWITCH
CHILLED WATER
LOW TEMP CUTOUT
PURGE OPERATING VALVES (6)
Fig. 2 - 19DA Rear View
1 .
2 .
Record and date vacuum reading shown on
compound pressure gage located on compres­
sor (Fig. 1).
With this reading and the reading taken when
the machine was received, determine vacuum
leak rate using the following formula:
Leak Rate = Vacuum loss
H- No. of days between readings
3. If vacuum leak rate is 0.05 in. Hg or less per
24 hours, the machine is sufficiently tight.
If vacuum leak rate exceeds this rate, per­
form "Refrigerant Pressure Test” and cor­
rect leakage.
EXCESSIVE OR TOTAL VACUUM LOSS - Ex­
cessive or total vacuum loss can be caused by
accidental opening of a valve or other connec­
tion. If this is suspected, proceed as follows:
1. Install a mercury manometer (absolute pres­
sure type) to the cooler charging valve (Fig. 1).
A dial type gage can not indicate the small
amount of leakage acceptable during a short
period of time.
2. Pull a vacuum on the machine equal to 25 in.
Hg. Use external vacuum pump or energize
purge pump (Fig. 2) using operation No. 2
described on the purge valve operation plate
shown on Fig. 2.
3. Let the machine stand with this vacuum, and
then perform the leak rate check previously
outlined.
4. If the vacuum leak rate is 0.05 in. Hg or less
per 24 hours, the machine is sufficiently tight.
Perform all steps under "Machine Dehydra­
tion" (pg 3).
5. If the vacuum leak rate exceeds 0.05 in. Hg
per 24 hours, perform all steps under "Re­
frigerant Pressure Test" (pg 2) and correct
leakage. Perform all steps under "Machine
Dehydration."
6. Remove the mercury manometer from cooler
charging valve.
REFRIGERANT PRESSURE TEST
1. Pull approximately five inches of vacuum on
the machine by energizing machine purge pump
(Fig. 2). Use operation No. 2 described on the
purge valve operation plate or with an external
vacuum pump connected to the cooler charging
valve (Fig. 1).
2. Charge approximately one gallon of Refrig­
erant 11 thru the cooler charging valve. Refer
to refrigerant charging instructions (pg 4).
3. Increase pressure to eight to ten psi with dry
air or nitrogen thru the cooler charging valve.
DO NOT EXCEED TEN PSI.
4. Test all joints, valves, fittings, flanges, etc.
with a halide or electronic leak detector.
CAUTION: Due to rupture disc limitations :
DO NOT EXCEED TEN PSI.