MIL-PRF-13312 Refrigeration Units, Mechanical, Panel Mounted, 10,000 Btu For Refrigerator, Prefabricated, Panel TypeThis document covers two types of panel mounted, mechanical, refrigeration units having a capacity of 10,000 British thermal units \(Btu\) per hour and used with the prefabricated, panel type refrigerator \(see 6.1\).

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MIL-PRF-13312R

shall be installed inside the calorimeter. The electrical energy of the fan motor shall be measured by

the same meter used for the heating elements in subparagraph (c) and this heat equivalent shall be

added to other sources of heat added to the calorimeter.

b. Four thermocouples, shielded from the effects of radiant heat, shall be installed inside the

calorimeter and positioned within 6 inches of the ceiling and floor at two opposite corners. The

interior temperature shall be taken as the average of the four thermocouples.

c. Heating elements shall be installed approximately in the center of the calorimeter. Electrical

heat input shall be measured by a watt-hour meter with a scale increment of 0.1 kilowatt-hour or less.

d. Eight thermometers or thermocouples, shielded from the effects of the radiant heat, shall be

installed approximately 18 inches from each corner of the calorimeter in the room where it is placed.

The ambient temperature shall be taken as the average of these eight temperatures.

e. All openings in the calorimeter shall be sealed, and the calorimeter shall remain undisturbed

throughout the test.

f. The ambient temperature shall then be maintained constant within + 20F. Sufficient, steady,

non-varying heat shall be added to the interior of the calorimeter to maintain a minimum of 600 F and a

maximum of 1000 F temperature difference between the interior and exterior of the calorimeter.

g. The test shall be considered concluded when eight consecutive half-hourly readings indicate

that:

1. The ambient temperature has been maintained constant within +20F.

2. The temperature inside the calorimeter has been maintained constant within + 10F.

h. The overall heat leakage coefficient U (Btu/hr/0 F) of the calorimeter is given by:

U =

(T1 - T2)

H1 = Sum of all electrical heat energies added to the calorimeter,

Btu/hr.

T1 = Average interior temperature of the calorimeter,

(1000F to 1550F).

T2 = Average ambient temperature, (T1 - T2) shall be in the

range of 600 F to 1000 F.

i. The test calorimeter shall not be used until a heat leakage coefficient no greater than