3.2.1.1
Prior to pneumatic testing, equipment which has been factory tested and
refrigerant charged as well as equipment which could be damaged or cause
personnel injury by imposed test pressure, positive or negative, shall be
isolated from the test pressure or removed from the system. Safety relief
valves and rupture discs, where not part of factory sealed systems, shall
be removed and openings capped or plugged.
3.2.1.2
Pneumatic Test
Pressure control and excess pressure protection shall be provided at the
source of test pressure. Valves shall be wide open, except those leading
to the atmosphere. Test gas shall be dry nitrogen, with minus 56.7 degrees
C minus 70 degree F dewpoint and less than 5 ppm oil. Test pressure shall
be applied in two stages before any refrigerant pipe is insulated or
covered. First stage test shall be at 69 kPa 10 psig with every joint
being tested with a thick soap or color indicating solution. Second stage
tests shall raise the system to the minimum refrigerant leakage test
pressure specified in ASHRAE 15 or IIAR 2 with a maximum test pressure of
25 percent greater than specified. Ammonia unloading lines shall be tested
at 2415 kPa 350 psig. Pressure above 690 kPa 100 psigshall be raised in 10
percent increments with a pressure acclimatizing period between increments.
The initial test pressure shall be recorded along with the ambient
temperature to which the system is exposed. Final test pressures of the
second stage shall be maintained on the system for a minimum of 24 hours.
At the end of the 24 hour period, the system pressure shall be recorded
along with the ambient temperature to which the system is exposed. A
correction factor of 2 kPa 0.3 psi will be allowed for each degree change
between test space initial and final ambient temperature, plus for increase
and minus for a decrease. If the corrected system pressure is not exactly
equal to the initial system test pressure, the system shall be investigated
for leaking joints. To repair leaks, the joint shall be taken apart,
thoroughly cleaned, and reconstructed as a new joint. Joints repaired by
caulking, remelting, or back-welding/brazing will not be acceptable.
Following repair, the entire system shall be retested using the pneumatic
tests described above. The entire system shall be reassembled once the
pneumatic tests are satisfactorily completed.
3.2.1.3
Evacuation Test
Following satisfactory completion of the pneumatic tests, the pressure
shall be relieved and the entire system shall be evacuated to an absolute
pressure of 300 microns. During evacuation of the system, the ambient
temperature shall be higher than 2 degrees C 35 degrees F. No more than
one system shall be evacuated at one time by one vacuum pump. Once the
desired vacuum has been reached, the vacuum line shall be closed and the
system shall stand for 1 hour. If the pressure rises over 500 microns
after the 1 hour period, the system shall be evacuated again down to 300
microns and let set for another 1 hour period. The system shall not be
charged until a vacuum of at least 500 microns is maintained for a period
of 1 hour without the assistance of a vacuum line. If, during the testing,
the pressure continues to rise, the system shall be checked for leaks,
repaired as required, and the evacuation procedure repeated. During
evacuation, pressures shall be recorded by a thermocouple type, electronic
type, or a calibrated-micron type gauge.
SECTION 15652A
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