MIL-DTL-19068B
than 3 feet in length. The line and fitting sizes shall be not smaller than the corresponding size of
the test valve. Pressure drop at rated flow through the directional control valve shall be not
greater than the maximum allowable value for the corresponding size specified in table II. The
valve shall be subjected to 109 cycles of flow reversals. The shuttle valve shall also be subjected
to this washout test with the inlet ports interchanged. The leakage shall meet the requirements as
specified in 3.12.3.
4.6.5 Leakage and shuttling with fluid. Set up the test similar to figure 2. Unless
otherwise specified, conduct the test with a fluid at a temperature of 100 °F. Plug the outlet port
and position the 3-way-valve so that the unconnected inlet port is down and open to the
atmosphere. With the system bled of air, the power driven pump and needle valve shall be
adjusted until the valve shuttles at a flow rate not exceeding 10 cubic inches per minute.
Observe the leakage and the leakage shall meet the requirements specified in 3.12.4. The
pressure for shuttling shall be observed. It shall be between 25 and 100 psi. A pressure of 5 psi
shall then be applied to the valve for 32 minutes. The leakage in a 30-minute period following a
2-minute seating period shall be not greater than 5 drops (.25 cc). The pressure shall then be
raised to a rated pressure of 3,000 psi and there shall be no leakage in a 30-minute period
following a 2-minute seating time. The valves shall also meet this test requirement with the inlet
ports interchanged.
4.6.6 Air pressure shuttling and leakage. Perform the test with air within a temperature
range of 70 to 120 oF. Set up the test valve similar to figure 3. Wet the test shuttle valve
internally, but do not fill with hydraulic fluid. With the air pressure reducing valve set at 100
psi, and shutoff valve "A" closed, the quick-opening type valve "B" opened, the valve shall
shuttle satisfactorily. Leakage of air past the shuttle valve piston as collected in the graduate
shall be not greater than 10 cubic inches of free air per shuttling cycle. Adjust the air pressure to
15 psi, and observe the leakage. Raise the pressure to 3,000 psi rated pressure and check the
leakage. The leakage shall meet the requirement specified in 3.12.5.
4.6.7 Extreme temperature functioning.
4.6.7.1 Low temperature functioning. Set up the test similar to figure 4. The
temperature shall be maintained at -65 °F for a period of 4 hours. After this period, the valve
shall be shuttled at least five times by means of the hand pump. After the fifth actuation, the
shuttling pressure and leakage shall be observed and shall meet the requirements specified in
3.12.4.
4.6.7.2 Rapid warm up. The low-temperature test setup shall allow the test fluid to warm
up rapidly to a temperature of 275 °F. While the temperature is being raised and without waiting
for the temperature to stabilize throughout the setup, the valve shall be shuttled at approximately
70 °F differentials in ambient temperature and the shuttling pressure shall be observed and shall
meet the requirements specified in 3.12.4.
4.6.7.3 High temperature functioning. Unless otherwise specified, this test shall be
conducted at a fluid temperature of 275 oF. The test valve shall then be shuttled at least five
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