MIL-PRF-13312R
25 Btu/hr/0 is obtained.
4.3.2.3.2 Capacity test (00F). The capacity of the refrigeration unit for low temperature shall be
verified to be no less than 10,000 Btu/hr using the method described below. Recorded data shall be
required and shall include all specified temperature readings, electrical heat input, suction and
discharge pressures, and complete calculations. All panels and doors of the refrigeration unit shall be
in the closed position.
a. All accessories and appurtenances shall be in their proper place.
b. Thermocouples, shielded from the effects of radiant heat, shall be installed in the air streams
entering the evaporator and leaving the evaporator section.
c. Shielded thermocouples shall be located at the approximate center of four equal areas of the
condenser face. The condenser inlet temperature will be taken as the average of these four
temperatures.
d. Recording pressure gages shall be used for the compressor suction and discharge pressures.
e. The procedures described in 4.3.2.3.1 (b), (c), (d), and (e) shall be followed for this test.
f. The refrigeration unit shall then be operated with air surrounding the condenser section and
entering the condenser at 1100F, +20F , and sufficient, steady, non-varying heat shall be added to the
interior of the calorimeter to maintain 00 F temperature of air entering the evaporator, + 10F. A watt-
hour meter with scale increments of 0.1 kilowatt-hour or less shall be used to indicate the quantity of
electrical energy added. Air velocity shall not exceed 100 feet per minute at any point 3 feet from the
refrigeration unit.
g. The test shall be considered concluded when eight consecutive half-hourly readings indicate
that:
1. The average calorimeter ambient temperature, T3 has been maintained at steady state
of + 20F at a temperature of 1000F to 1100F.
2. Return air temperature, T4, entering the evaporator has been maintained at 00 F + 10F.
3. The net refrigerator capacity shall be considered as the sum of the electrical energy, in
Btu/hr, added during this test plus the heat leakage gain in Btu/hr, as calculated from the calibration
specified in 4.3.2.3.1.
The net refrigeration capacity is given by:
Q = U (T3 - T4) + H2
Q = Net refrigeration capacity in Btu/hr
U = Overall heat leakage coefficient Btu/hr/0 F as determined by paragraph (h)
in 4.3.2.3.1
H2 = Sum of all heat energy added to the interior of the calorimeter in
Btu/hr, (f) above.
4.3.2.3.3 Capacity test (350F). The procedure specified in 4.3.2.3.2 shall be followed with the
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