MIL-PRF-44035B
previously-qualified designs.
4.3.1 Verification alternatives. The contractor may propose
alternative test methods, techniques, or equipment, including the
application of statistical process control, tool control, or
cost-effective sampling procedures to verify performance (see
6.4).
4.3.2 Operating requirements verification.
All operating
requirements shall be verified as follows:
4.3.2.1 4-hour operation test. The refrigeration unit
evaporator shall be clamped to the evaporator opening of a
calorimeter or other insulated structure. All refrigeration unit
components shall be in place and all doors and panels shall be
closed. The refrigeration unit shall be operated for 4 hours to
determine that all mechanical and electrical components,
including heater circuit operation, are functioning as intended
and all controls are in calibration. The units shall have a heat
load applied to the enclosure so that the unit operates more than
50 percent of the test time and cycles on automatic controls 3 or
more times per hour. Suction pressure at the compressor shall be
verified to be within the established guidelines of the
compressor manufacturer. Prior to completion of the 4-hour test,
the air flow to the condenser shall be blocked off and the unit
operated until automatic shutdown of the refrigeration unit is
verified when the compressor discharge pressure limit is
exceeded. This compressor discharge limit shall be that
recommended by the compressor manufacturer for the refrigerant
used. The air exiting the evaporator shall be checked to verify
that the airflow direction is out and upward.
After a minimum operating time of 1 hour, with the thermostat
set a 0 F, the moisture indicator shall be observed to verify
that the moisture content as shown by the component
manufacturer's color chart data is not greater than 25 ppm. A
check for refrigerant leakage shall also be performed with the
unit inoperative, with a leak detector having a maximum
sensitivity of 0.40 oz per year. Verify that leakage is no
greater than 0.5 oz per year. Verify that the compressor shaft
seal leakage is no greater than 3 oz per year.
4.3.2.2 72-hour operating test. A 72-hour operating test shall
be conducted as follows:
a.
The refrigeration unit shall be clamped to the evaporator
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