MIL-PRF-49175C(CR)
3.5.1 Cooling capacity. The cooler with thermal load (copper mass) shall
provide the minimum refrigeration capacity at 80° K maximum as shown in figure
1, curve A.
3.5.2 Cooldown time. The cooldown time to reach a cold tip temperature
of 80° K from ambient with a 1440, (+25, -0) joule copper thermal mass (from 300°
K to 80° K) shall be in accordance with figure 2.
3.5.3 Input power. The total input power to the cooler shall not exceed
that shown in figure 3 with 1440, (+25, -0) joule thermal mass after cold tip
temperature has stabilized with the heat load shown in figure 1, curve A. The
input voltage shall be 117, ±2 volts alternating current (VAC), 400, ±20 hertz
(Hz) power source.
3.5.4 Acoustic noise. The cooler noise emission shall not be more than
the values listed below, when measured at a distance of 3 feet.
Sound pressure values
Center Frequency
Octave band
Maximum sound pressure
(Hz)
(Hz)
level(dB), ref.0.0002 microbar
125
87-175
45
250
175-350
45
500
350-700
48
1000
700-1400
55
2000
1400-2800
60
4000
2800-5600
65
8000
5600-11200
65
3.5.5 Leak rate. The leak rate of the cooler shall not be greater than
2.5 x 10-7 cubic centimeters per second (cc/sec) helium equivalent at an ambient
temperature of +23°C, ±5°C.
3.5.6 Vibration output. The maximum amplitude, at the ambient
temperature of +23°C ±5°C, of the vibrational force induced by the cooler at a
frequency of 26Hz ±4Hz or any of the next eight harmonics along the compressor
piston and coldfinger axes shall not exceed 0.35 pound (semi-amplitude) and
shall not exceed 0.5 pound (semi-amplitude) along the motor axis. The maximum
amplitude of the torque induced by the cooler about the motor, piston and
coldfinger axes at 26Hz ±4Hz or any of the next eight harmonics shall not
exceed:
a.
4.0 In-oz (semi-amplitude) compressor piston axis
b.
4.0 in-oz (semi-amplitude) coldfinger axis
c.
15.0 in-oz (semi-amplitude) motor axis.
3
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