MIL-DTL-5523E
influence the performance of the component, such as pistons operated by spring, etc., the maximum packing friction
anticipated shall be induced in the test specimen. In these cases O-ring packing glands shall be fabricated to provide
maximum design O-ring squeeze, including the effect of adverse O-ring cross section tolerances and high-swell
fluids. This specimen shall be marked "MIN".
4.4.1.2 Maximum clearance specimen. The second specimen shall be assembled of parts which have been selected
to provide that the clearance with regards to linear and diametrical tolerances between moving members, conducive
to malfunctioning as a result of wear associated with prolonged operation will be not less than 90 percent of the
maximum designed clearance permitted by the manufacturer's drawings. This specimen shall be marked "MAX".
4.4.1.3 Typical specimen. A specimen assembled from parts conforming to manufacturer's drawings. This
specimen shall be marked TYP.
4.4.1.4 Tolerance considerations. In machining these specimens, surface finishes shall be of no finer degree than
the surface finishes as will be produced on production units. Packing glands may be fabricated to nominal
dimensions. Lapped or selectively fitted parts need not be made to adverse limits. To facilitate fabrication of adverse
tolerance units, it is permissible for one of the mating parts required to produce the critical clearance to be outside of
drawing tolerances, provided that the clearance as established falls within the range specified. In the event that the
design clearances in themselves are extremely close, the 10-percent limitations on clearance may be adjusted or
waived entirely, but at the discretion of the qualifying activity. In case of waiver of adverse tolerance specimens, tests
shall be conducted on two representative production samples, and the test report shall analyze the effects of adverse
tolerance conditions.
4.4.2 First article tests. First article inspections shall be performed on each valve of the test sample, except where a
specific valve is identified in the test. The first article inspection shall consist of the following tests and shall be
performed in the sequence listed:
(see 4.4.2.1)
a. Examination of product.
b. Immersion.
(see 4.4.2.2)
c. Proof pressure.
(see 4.4.2.3.1)
d. Normal temperature performance.
(see 4.4.2.4)
e. Extreme temperature performance.
(see 4.4.2.5)
f. Burst pressure.
(see 4.4.2.3.2)
4.4.2.1 Examination of product. Each valve shall be examined in accordance with the requirements of 4.5.4.1.
4.4.2.2 Immersion.
4.4.2.2.1 Other nonmetallic parts. Components containing nonmetallic parts other than plastic parts or MS or AN
standard seals in glands conforming to MIL-G-5514 shall be immersed in hydraulic fluid for a period of 7 days at a
temperature of not less than 160°F (71.1°)prior to conducting the qualification tests specified herein. All internal parts
shall be in contact with the fluid during this period. If this test is necessary as a result of the use of nonstandard
packing installations, or if the packings pass over holes, ports, step diameters, threads, etc., and if the inside
diameter, outside diameter, or sides of the seal are unrestrained during any part of their normal operation, the
packing used in the test samples shall be fabricated of a compound specified in MIL-DTL-5516 having the highest
swell, and the fluid shall be that approved by MIL-PRF-5606, MIL-PRF-83282 or MIL-PRF-87257 having the highest
swell characteristics. (The Government will designate the applicable high-swell packing compound and fluid upon
request to the activity responsible for qualification.) After the above immersion, the equipment shall remain in the
high-swell fluid at normal room temperature until ready for test. It shall not be exposed to air for any appreciable
length of time during the tests.
4.4.2.3 Pressure tests.
4.4.2.3.1 Proof pressure type I system valves. Proof pressure, as specified for its class in table II, shall be applied
simultaneously to both the pressure and return ports at a rate not exceeding 25,000 psi per minute and held for at
least 2 minutes. When subjected to the rated proof pressure specified in table II the valve shall meet the
requirements of 3.5.1.
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