MIL-PRF-25439C
b. Dielectric strength
c. Leak test
d. Scale error and friction
e. Phase angle tolerance
4.4.2 Sampling tests. Unless otherwise specified a minimum of 2 transmitters shall be
selected at random from each 100 items produced on the contract or order and subjected to all
the tests as described under 4.5.
4.4.3 Rejection and Retest. When an item selected from a production run fails to meet
the tests of this specification, no items still on hand or later produced shall be accepted until the
extent and cause of the failure have been determined and corrected. The contractor shall provide
a written explanation as to the cause of the failures and the actions taken to preclude recurrence.
After correction, all tests shall be repeated. For production reasons individual tests may be
continued pending the investigation of a sampling test failure but final acceptance of these items
shall not be made until it is determined that all items meet all the requirements of this
specification. IF investigation indicates that defects may exist in items already accepted the
contractor shall notify the procuring activity of these defects and the method of correcting them.
4.5 Test Methods.
4.5.1 Physical examination. The transmitter shall be inspected to determine compliance
with this specification with respect to materials, workmanship, identification and dimensions.
4.5.2 Dielectric strength. Prior to sealing, 550 V AC at a commercial frequency shall be
applied to certain pins and the case for a period of 5 seconds. Only those pins not used for
grounding the components to the case shall be used. There shall be no insulation breakdown.
4.5.3 Leak test. The transmitter shall be connected to a hydraulic pump or other source
of hydraulic pressure and a proof pressure of 240 psi applied and maintained for a period of 5
minutes. There shall be no leakage or damage as a result of this test.
4.5.4 Scale error and friction. The test points shall be as noted in Table I. The scale error
shall not exceed the tolerance in Table I. The friction error shall be determined at the mid-scale
point by bringing the flow up to, but not exceeding, the specified rate and then down to, but not
below, the specified rate. The difference between the upscale and downscale reading shall not
exceed the tolerance in Table II. Tapping shall not be used when making the friction error
readings. The transmitter shall be tested on a flow stand capable of determining the true flow
within an accuracy of ±0.5% of the point.
4.5.5 Phase angle tolerances. The phase angle tolerances at the test points shall not
exceed the values shown in Table III.
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