MIL-PRF-24758A(SH)
remain properly assembled to the conduit and there shall be no damage visible to normal or corrected vision without
additional magnification.
Flexing. To determine conformance with the conduit flexibility requirements of 3.7.5, each
4.7.5
representative sample of conduit system shall be tested as specified in IEC 60614-2-5. After the test, there shall be
no structural damage visible to normal or corrected vision without additional magnification, and the stated
classification level of protection for the conduits shall not be reduced.
Resistance to heat. To determine conformance with the conduit resistance to heat requirement of
4.7.6
3.7.6, each representative sample of conduit shall be tested as specified in IEC 60614-2-5, except the high
temperature shall be 257 °F (125 °C). The samples are to be conditioned at the high temperature for 4 hours, then
loaded with the specified weight, and returned to the heating cabinet for 24 hours. Verification shall be the vertical
passing of the specified test gauge through the samples, once cooled to room temperature. To determine
conformance with the fitting resistance to heat requirements of 3.7.6, each representative sample fitting, as
appropriate, shall be tested as specified in IEC 61035-2-3 at a temperature of 257 °F (125 °C).
Resistance to flame-propagation. To determine conformance with the resistance to flame-propagation
4.7.7
requirements of 3.7.7, each representative sample of conduit shall be tested as specified in IEC 60614-1. The test
flame shall be as specified in IEC 60695-2-4/1. The time exposure of the sample to the test flame shall be 60+5
seconds. Representative samples 26.57±0.39 inches (675±10 mm) in length are mounted vertically in a rectangular
metal enclosure, which has one open side, in a draft free surrounding. Mounting is by means of two metal clamps
equidistant from each end of the sample. A steel rod, of a diameter as specified, passed centrally through and
extending to the bottom of the sample, is independently mounted at the enclosure top. A piece of white pine board
approximately 0.39 inches (10 mm) thick covered with a single layer of tissue paper, as specified, is positioned
below the sample. After the removal of the flame and after the burning of the sample has ceased, the surface of the
sample is wiped clean by rubbing with a piece of cloth soaked with water. If the sample has no evidence of burning
or charring within 1.96 inches (50 mm) of any part of the clamp, or ceases to propagate flame after 30 seconds of
removal of test flame, and the tissue paper does not ignite, the sample shall be deemed to have passed the test.
Acid gas emission. To determine conformance with the level of acid gas emission requirement of
4.7.8
3.8.8, each representative sample of conduit shall be tested as specified in IEC 60754-2.
Shock. To determine conformance with the conduit system shock requirements of 3.7.9, each
4.7.9
representative sample of conduit shall be tested as specified in MIL-S-901.
4.8 Weatherproofing. To determine conformance with the conduit system ingress of water requirement of
3.8, each representative sample of conduit system shall be tested as specified in IEC 60529 clause 14.2.6. The
assembly with both end fittings plugged is deemed to have passed the test if no ingress of water is detected inside
the test sample following the test.
4.9 External corrosion. Conformance to the external corrosion requirements of 3.9 shall be verified by a
cyclic sulfur dioxide/salt fog (SO2/NaCl) test. The test sample shall be a representative conduit system. The test
chamber shall be per ASTM B117. The test conditions shall include a 30±2-min spray of 5% NaCl salt solution,
then a 30±2-min exposure to SO2 gas flow of 35 cm2/min/m3, followed by a 120±4-min rest period, to be repeated
for four weeks. Upon completion of the test, the sample shall be examined for visual evidence of corrosion. Any
corrosion, rust, staining, pitting, scaling, or other evidence of corrosion shall constitute failure to conform to the
requirements of 3.9.
Corrosion and polluting materials. To determine conformance with the conduit corrosion and
4.9.1
polluting materials requirement of 3.9.l, each representative sample of conduit system shall be tested as specified in
IEC 60614-1 with the flexible conduits flexed to their minimum bend radius.
4.9.2 Solar radiation. To determine conformance with the conduit solar radiation protection requirements of
3.9.2, each representative sample of conduit system shall be tested as specified in IEC 60068-2-5.
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