MIL-PRF-13312R
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 the refrigeration unit doors shall be closed. The refrigeration unit shall be
operated for 4 hours to determine that all mechanical and electrical components 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 the automatic controls three
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 and automatic shutdown of the
refrigeration unit verified when compressor discharge limit is exceeded. During normal operation, the
discharge pressure shall be observed to be not less than 100 pounds per square inch gage (psig).
4.3.2.2 72-hour operating test. A 72-hour test shall be conducted as follows:
a. The refrigeration unit shall be clamped to the evaporator opening of a calorimeter or
other insulated structure.
b. A combined heat load of 7000 Btu/hr shall be impressed.
c. The refrigeration unit shall be operated 36 hours with the thermostat set at 00 F and 36
hours with the thermostat set at 35 0F. During this test, suction and discharge pressure, ambient air,
condenser air, and evaporator in and out air temperatures shall be recorded on automatic recording
instruments. Normal maintenance shall be performed during this test and verification shall be made
that rated conditions are maintained during the 72-hour period in an ambient temperature of 1100 F.
d. After a minimum operating time of 1 hour with the thermostat set at 00 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 parts per million. A check for refrigerant
leakage shall also be performed with a leak detector having a maximum sensitivity of 0.40 oz per
year. Leakage shall be checked to verify that it is no greater than 0.5 oz per year, except the
compressor shaft seal leakage is no greater than 3.0 oz per year.
e. When the refrigeration unit being tested is a type I unit, the fuel consumption shall be
monitored and recorded. Verification shall be made that the unit operates no less than 44 hours
before refueling.
4.3.2.3 Refrigeration capacity tests.
4.3.2.3.1 Calorimeter calibration. The calorimeter calibration shall be run once prior to capacity
tests to establish the coefficient of heat leakage to be used for capacity calculation. The coefficient of
heat leakage for the calorimeter shall not exceed 25 Btu/hr/0F and the volume shall not be less than
150 cubic feet. A refrigeration unit shall be bolted to the evaporator opening in the calorimeter with a
minimum 5-foot clearance on the front of the unit and the overall heat leakage coefficient shall be
determined as follows:
a. An electric fan(s), of a sufficient capacity to insure that no uncirculated air pocket will exist,
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