MIL-DTL-5516D
4.5.4 Performance tests. The following performance tests shall be conducted in the sequence
listed. All packings shall be installed in the applicable glands of a test cylinder similar to figure 3,
and the cylinder filled with hydraulic oil conforming to Specification MIL-PRF-5606 at no pressure.
The cylinder with packings installed shall be maintained at 70° ± 1°C (158° ± 2°F) for 6 days prior
to performance tests. All packings and the metals in contact with the packings shall be inspected
at termination of this period for sticky or gummy residue, permanent set, or swelling of the
packings and discoloration or corrosion of the metals. These data shall be recorded for use in
conjunction with later results of the test for evaluation of performance.
4.5.4.1 High-temperature performance.
4.5.4.1.1 High-temperature leakage. At completion of the preceding preparation, the packings
shall be installed in a controlled temperature chamber as indicated in figure 4 (only the apparatus
indicated within the upper left-hand corner of figure 4 is applicable to this test). The hydraulic
fluid used for testing shall be the type conforming to Specification MIL-PRF-5606. The pressure
in the entire system shall be raised to 1,500 psi (10.34 Mpa) with the piston near one end of the
cylinder, but not bottomed, and necessary valves adjusted to prevent motion. The temperature in
the test box shall be raised to 71°C (160°F) minimum within a period of 60 minutes, and shall
remain at this temperature and pressure for 24 hours. Upon completion of the 24-hour period,
the following cycling and static operations shall be accomplished in the order listed. (The
specified temperature shall be maintained throughout the test.)
(a) High-pressure cycling. At least 10 cycles of operation at a 1,500 psi (10.34 Mpa)
pressure shall be made by opening the proper valves between the cylinder and the accumulator
and bleeding pressure from the opposite end of the cylinder to the reservoir.
(b) Low-pressure cycling. At least 10 cycles of operation at low pressure shall be made by
opening the proper valves between the cylinder and the reservoir and bleeding just enough
pressure from the accumulator to cycle the cylinder at slow motion. The pressure shall be
recorded.
(c) Low-pressure static. The hydraulic pressure in the test cylinder shall be lowered to 5 to
10 psi (.034 to .069 Mpa) pressure and the installation allowed to set for 1 hour to determine low-
pressure static leakage.
The total leakage during entire test shall not exceed three drops (approximately 0.15 cc) from
each packing gland. The leakage shall be recorded.
4.5.4.1.2 High-temperature breakout. Upon completion of the high temperature leakage test, the
hydraulic pressure in the entire system shall be again pumped up to 1,500 psi (10.34 Mpa). With
the piston held static and a 1,500 psi (10.34 Mpa) pressure maintained, the temperature in the
box shall be maintained at 71°C (160°F) minimum for 3 hours after which time the source of heat
shall be turned off and the entire apparatus allowed to cool to room temperature over
approximately a 20-hour period. Pressure shall not fall below 1,000 psi (6.89 Mpa) during this 20-
hour period. A no-load breakout test shall then be performed by closing the valve between the
accumulator and cylinder, exhausting the pressure in each end of the test cylinder
simultaneously, and recording the lowest pressure necessary to start motion of the piston. The
pressure required for breakout shall not exceed 30 psi (.207 Mpa) for V-ring packings. Leakage
during the period of this portion of the test shall not exceed two drops (approximately 0.10 cc) per
gland. Breakout pressure and leakage shall be recorded.
4.5.4.2 Low-temperature performance.
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