MIL-PRF-25439C
TABLE III. Phase angle tolerance.
Phase Angle Tolerance, Degree ±
Flow
Room
Low
High
PPM
Temp
Temp
Temp
0
--
--
--
2,000
1.0
1.5
1.5
4,000
0.5
1.0
1.0
6,000
0.5
1.0
1.0
8,000
1.0
1.5
1.5
10,000
1.5
2.0
2.0
4.5.7 Low temperature scale error and friction. The transmitter shall be subjected to a
temperature of approximately -54°C for a period of 4 hours. While still at this temperature, the
transmitter shall be tested for scale error and friction as specified in 4.5.4. The scale error and the
friction error shall not exceed the tolerances specified in Tables I, II, and III. The fuel use in this
test shall be at a room temperature, and the ambient temperature around the transmitter shall be
maintained at approximately -54°C.
4.5.8 Low temperature leak. The transmitter shall be subjected to a temperature of
approximately -54°C for a period of 4 hours. While the transmitter and fuel are still at this
temperature, the test specified in 4.5.3 shall be repeated. There shall be no leaks and the
transmitter shall not be damaged as a result of this test. This test may be combined with the test
specified in 4.5.7.
4.5.9 High temperature scale error and friction. The transmitter shall be subjected to a
temperature of approximately 70°C for a period of 4 hours. While still at this temperature, the
transmitter shall be tested for scale error and friction error as specified in 4.5.4. The scale error
and friction error shall not exceed the tolerances in Tables I, II, and III. The fuel used in this test
shall be at room temperature, and the ambient temperature around the transmitter shall be
maintained at approximately 70°C.
4.5.10 Vibration resonances. For the vibration resonances tests, the transmitter shall be
subjected to the following frequency range and vibratory acceleration or double amplitude:
Frequency (cpm)
Amplitude
300 - 600
0.010 inch
6,000 - 30,000
±5g
30,000 - 60,000
±5 g
4.5.10.1 When conducting the vibration resonance test and observing errors, the fuel
flow rate shall be approximately 1,000 ppm. During this test, when the output signal error is not
being observed, the vibration may be applied with zero flow but with fuel in the transmitter.
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