MIL-DTL-27190C
4.5.7 Vibration. The indicator shall be subjected to a vibration test in accordance with
MIL-STD-810, method 514, procedure I. A synchro signal shall be maintained on the stators of
the indicator synchro to provide an indication of 2,000 psi. Pointer oscillation shall not exceed
200 psi double amplitude. Upon completion of this test, the indicator shall be subjected to the
scale error test at room temperature. The scale errors shall not exceed the tolerances specified in
table II.
4.5.8 Low temperature. The indicator shall be subjected to a temperature of -55 °C ± 2 °C
for a period of 4 hours. While at this temperature, it shall be checked for scale error and friction.
The tolerances shall not exceed those specified in tables II and III. In every case, the indicator
shall not require more than 3 seconds to come within the tolerance specified.
4.5.9 High temperature. The indicator shall be subjected to a temperature of 72 °C for a
period of 4 hours. While at this temperature, it shall be checked for scale errors. The scale error
and friction shall not exceed those specified in tables II and III. The response time shall not
exceed 3 seconds.
4.5.10 Fogging. The indicator shall be placed in a controlled ambient temperature of
85 °C ± 5 °C for a minimum period of 2 hours. Within 10 seconds after removal from the oven,
the indicator shall be immersed to a depth of 1/4 inch in an ice water bath maintained at 0 °C to
7 °C. After 3 minutes, the indicator shall be removed from the fluid bath and quickly wiped dry
(compressed air shall not be used). The cover glass and dial shall immediately be inspected and
any evidence of fogging or damage shall be cause for rejection.
4.5.11 Step input response. The indicator pointer shall be positioned at approximately
0 psi pressure. With excitation power off, the test transmitter shall be positioned to the
equivalent of 2,000 psi. Excitation power shall then be applied and the time required for the
indicator to indicate 2,000 psi ± 100 psi shall not exceed 2.0 seconds. The pointer shall move
smoothly and shall not oscillate and shall not overshoot more than two times.
4.5.12 Voltage and frequency variation. The indicator shall meet the test specified in
4.5.11 and the scale error and friction tolerances specified in tables II and III when the voltage
and frequency are varied from 22 V to 30 V and 320 cps to 480 cps or any combination thereof.
4.5.13 Secondary voltage. The maximum open-circuit voltage shall be measured
between any two secondary leads and shall be 11.8 V ± 3 percent. The variation between the
three maximum secondary voltages on the indicator synchro as measured between any two stator
leads shall not exceed 0.2 V.
4.5.14 Magnetic effect. The indicator, first not operating and second, operating on rated
voltage, shall be rotated in a vertical plane about a short bar magnet compass with the nearest part
of the indicator 5-1/2 inches from and magnetically east or west of the center of the compass.
Starting directly under the compass, the indicator shall be held in positions 0 degrees, 45 degrees,
90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees from the initial
position. At each of these positions, the indicator shall be rotated on its own horizontal axis until it
is in its normal upright position. The horizontal magnetic field intensity shall be 0.17 oersted to
0.19 oersted. Deflection of the compass at any of the specified positions shall not exceed 3 degrees.
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