MIL-DTL-24402F(SH)
4.6.1.6 Differential pressure indicator operation.
4.6.1.6.1 Mechanical-type indicator. With the outlet unpressurized, the inlet pressure shall be increased slowly
until the pressure indicator actuates. The actuation pressure shall be higher than the outlet pressure by the value
specified in MIL-DTL-24402/5. This test shall be repeated with the outlet pressurized to 50 and 3,000 lb/inē. After
actuation, it shall be demonstrated that the indicator will remain actuated when the inlet pressure is reduced to zero
with outlet pressures of 0, 50, and 3,000 lb/inē, and that the actuators can be manually depressed to the normal reset
position under these conditions. With the outlet pressurized to 50 and 3,000 lb/inē, a differential pressure of a value,
as specified in MIL-DTL-24402/5, of 5 seconds duration shall not cause the indicator to actuate.
The above qualification tests shall be performed after completion of shock, fatigue impulse, vibration, and proof
pressure tests. For conformance, the actuation pressure of each indicator shall be verified to be higher than the
outlet pressure by the value specified in MIL-DTL-24402/5. This test may be conducted with the outlet port
unpressurized.
4.6.1.6.2 Electrical-type port. For qualification testing, the electrical differential pressure indicators shall be
tested for operation in accordance with 4.6.1.6.1. During operational tests, it shall be verified that the electrical
contacts trip in conjunction with the actuation and reset of the red indicator (see 3.5.3.1.2). For conformance, the
actuation pressure for both the red indicator and electrical switch of each indicator shall be verified to be higher, by
the value specified in the applicable specification sheet, than the outlet pressure.
4.6.1.6.3 Gauge-type indicator. For gauge-type differential pressure indicators, the gauge shall be subjected to
forward and reverse differential pressures up to 3,000 lb/inē. Differential pressure shall be maintained at 3,000 lb/inē
for 1 minute. After all tests, including shock, fatigue impulse, vibration, and proof pressure, the gauge shall read
within the specified accuracy in the differential pressure range specified in 3.5.3.1.3. The gauge shall be tested in
both the ascending and descending pressure modes of operation at 20-lb/inē intervals from the lowest to highest
pressure range, inclusive. An indicator response time of less than 20 seconds for a 50-lb/inē change in pressure shall
be demonstrated. For conformance, the accuracy of each indicator shall be verified at a pressure interval of
25 percent of gauge pressure range, starting from the lowest to highest pressure range in both ascending and
descending pressure modes.
4.6.1.7 Relief valve operation.
4.6.1.7.1 Relief valve (qualification). Filter assemblies with an integral relief valve shall be tested for relief
valve operation. For this test, dummy elements which stop flow shall be installed. Relief valve performance
requirements shall be in accordance with the applicable specification sheet. Test procedures shall be as follows:
a. Cracking pressure (see 6.8.1). Relief valve cracking differential pressure shall be determined by applying
pressure at the inlet port of the filter assembly with a power-driven pump. Starting at 80 percent of the minimum
cracking pressure, pressure shall be increased in increments not to exceed 5 percent of cracking pressure. At each
pressure increment, leakage shall be measured for not less than 1 minute.
b. Full flow. The pressure differential across the valve shall be increased until rated flow is obtained or until
the maximum allowed full flow differential pressure is exceeded (see the applicable specification sheet for rated
flow, maximum full flow differential pressure, and test fluid). Rated flow shall occur at a differential pressure less
than the maximum specified value.
c. Minimum reseat pressure (see 6.8.2). With the bypass relief valve flowing at least 10 percent of rated flow,
the inlet pressure shall be reduced below the cracking pressure in increments not to exceed 5 percent of the
minimum cracking pressure. At each pressure increment, leakage shall be measured for not less than 1 minute. The
pressure shall be reduced until the leakage is less than that permitted by the applicable specification sheet.
4.6.1.7.2 Relief valve (conformance). Filter assemblies with an integral relief valve shall be tested as specified
in 4.6.1.7.1 to verify the cracking pressure and minimum reseat requirements specified for conformance on the
applicable specification sheet. For conformance, the cracking pressure test may be conducted at the maximum
permitted pressure and the reseat test at the minimum permitted pressure without testing at incremental pressures.
10
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business