MIL-PRF-62028D
4.3.1 Verification alternatives. The manufacturer may propose alternative test methods,
techniques, or equipment, including the application of statistical process control, tool control, or
cost-effective sampling procedures, to verify performance. See the contract for alternatives that
replace verifications required by this specification.
4.3.2 Inspection conditions. Unless otherwise specified (see 6.2), all inspections shall be
conducted under the following conditions:
a. Air temperature: 77 + 10°F
b. Barometric pressure: 28.5 (+2,-3) in. mercury.
c. Relative humidity: 50 + 30%.
4.3.3 Operating requirements verifications. Complete each verification under 4.3.3.
4.3.3.1 Leakage. The hose shall be pressurized with air to the maximum working
pressure as specified in table I for a period of 1 minute. A leakage rate greater than 0.02 ft3/min,
per in. of inside diameter (ID), per ft of length shall constitute failure of this test.
4.3.3.2 Proof and burst pressures. The hose shall be tested IAW ASTM D380 at the
proof and burst pressures specified in table II. A rupture of the hose shall constitute failure of this
test.
4.3.3.3 Vacuum resistance. A 36-in. length of hose shall be assembled with end
couplings. One end shall be closed in such a manner as to prevent leakage of air, and the other
end shall be connected to a vacuum pump. The hose shall then be subjected to a vacuum of 10 in.
of mercury while curved to a radius equal to five times the OD of the hose for a period of
5 minutes. Subsequent to testing, a reduction of the hose OD greater than 5%, or a collapsed or
separated hose ID, shall constitute failure of this test.
4.3.3.4 Flexibility. The hose shall be marked at four points spaced 90° apart around the
external perimeter. The hose shall then be bent successively on each of the four marked points at
180° around a rigid cylinder with a diameter equal to the ID of the hose. Subsequent to testing,
evidence of permanent kinking, flattening, fracturing, or deformation in excess of 2% shall
constitute failure of this test.
4.3.3.5 Collapsing resistance. A 6-in. longitudinal section of a 36-in. test specimen shall
be subjected to a load of 50 lb minimum, applied within 15 seconds. The load shall be applied
perpendicular to the hose axis for a period of at least 5 minutes. When the load is removed,
evidence of permanent setting, distortion, or deformation in excess of 5% shall constitute failure
of this test.
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