MIL-DTL-25867D
4.5.15 Sand and dust. The gage shall be subjected to a sand and dust test in accordance
with MIL-STD-810F, Method 510.4, procedure I. At the completion of this test the gage shall be
removed from the test chamber, allowed to cool to room temperature, and then subjected to the
scale error test (at room temperature) and friction error test. The scale error and friction error
shall not exceed the tolerances specified in table II.
4.5.16 Overpressure. The gage shall be subjected to an overpressure of 135 percent of the
rated pressure for a period of 10 minutes. Not less than 1 hour after application of the specified
pressure, the gage shall be subjected to the scale error test at room temperature. The scale error
shall not exceed the tolerance specified in table II.
4.5.17 Reliability. Ten gages shall be tested for reliability. Recording, data handling, and
reporting shall be performed for the government. MIL-HDBK-781 may be used for guidance.
4.5.17.1 Reliability test. The test equipment and fixtures shall include provisions for
vibration and temperature cycling at periodic intervals specified herein. During this test, input
pressure shall be applied to the gage at a rate of 2 cpm to 3 cpm from 0 percent to 85 percent of
full scale and return. Completion of 4 hours of operation shall include at least 480 operational
cycles. For at least 10 minutes out of every hour of "ON" time, the gage shall be vibrated at
2.2g ± 10 percent peak acceleration value at any non-resonant frequency between 20 cycles per
second (cps) and 60 cps, measured at the mounting points on the equipment. The temperature
cycles shall be conducted in the following sequence: 4 hours at -55 ºC (-67 ºF), temperature
change to 50 ºC (122 ºF) at a minimum rate of 5 ºC (41 ºF) per minute; 4 hours at 50 ºC (122 ºF),
temperature change to -55 ºC (-67 ºF), and 4 hours at -55 ºC (-67 ºF). In case of malfunction, the
malfunction shall be recorded and the test interrupted while repairs are made. Upon completion
of each 250 hours of cycling, the gage shall be checked for scale error. The scale error reading
shall not exceed twice the room temperature tolerance in table II. No calibration shall be
performed on the units during this test. The test may be interrupted for weekend shutdown. The
contractor shall prepare a report that contains test procedures, details of any malfunctions, and
corrective actions taken. MIL-HDBK-781 may be used for guidance.
4.5.18 Vent. If a plug is used, one gage shall be subjected to a pressure sufficient to blow
out the plug or sealing device that fills the vent hole. The pressure shall be applied to the inside
of the case after the sensing element has been ruptured mechanically. The cover glass and case
shall not be ruptured or damaged as a result of this test.
4.6 Maintenance of qualification. At specified intervals determined by the qualifying
activity, the manufacturer must be able to demonstrate that the company still has the capabilities
and facilities necessary to produce the QPL items in accordance with this specification and in
accordance with the provisions governing qualification specified in SD-6.
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