MIL-DTL-17505F
4.7.3 Tube and cover thicknesses. The thicknesses of the tube and cover shall be measured on
specimens removed from each end of the hose section obtained in accordance with 4.5.2.5 to
determine conformance to 3.4. The thicknesses shall be determined by the procedures given in
ASTM D 380. The respective values found for the tube thickness shall not be averaged, but shall
be regarded as independent measurements, each of which shall meet the requirement. The
respective values for the cover thicknesses shall be treated in the same manner.
4.7.4 Resistance to vacuum. Hose selected shall be subjected for 5 minutes to a vacuum test
equivalent to 20 inches (508 mm) of mercury. One end of the hose shall be equipped with a
transparent cap and an electric light shall be used to permit visual examination for collapse or
failure.
4.7.5 Hydrostatic pressure test. Each length of hose, complete with fittings, flanges, or adapters
(or all), shall be subjected to a 250 psi (1 724 kPa) pressure test as follows:
a. Lay out the hose as straight as possible.
b. Fill with water, venting to remove all air and apply a pressure of 10 psi (69 kPa).
c. Mark off a test length of 50 inches (1 270 mm), clear of the end reinforcement, for later
measurement of elongation.
d. Increase the pressure, over a period of 5 minutes, from 10 psi (69 kPa) to half the test
pressure of 250 psi (1 724 kPa), (125 psi (862 kPa)), hold this for 10 minutes, then reduce
pressure over a period of 5 minutes to zero.
e. Raise the pressure over a period of 5 minutes to the full test pressure of 250 psi
(1 724 kPa), and hold it for 10 minutes.
f. Before releasing the full test pressure, measure the distance between the test marks to
ascertain the temporary elongation and record the increase as a percentage of the original
length measured at 10 psi (69 kPa).
g. Electrical conductivity: While subjected to 250 psi (1 724 kPa) pressure, each length of
hose shall be tested for electrical conductivity in an electrical circuit. Any hose that does
not meet electrical conductivity requirements (see 3.10) shall be rejected.
h. Reduce pressure over a period of 5 minutes to zero.
i. On the first hose tested in each lot, after an interval of not less than 15 minutes, raise the
pressure again to 10 psi (69 kPa). Measure the distance between the test marks to
ascertain the permanent elongation and record the increase as a percentage of the original
length measured at 10 psi (69 kPa). No other hose in the lot will require testing provided
that this hose meets the permanent elongation requirement. If the hose does not meet the
permanent elongation requirement, all hose in the lot shall be tested.
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