 |
|||
|
Page Title:
Extreme temperature functioning |
|
||
| ||||||||||
|
|  MIL-V-19067A(ASG)
4.4.8
Extreme temperature functioning.-
Low temperature functioning - The valve snail be connected to a static
4.4.8.1
head of 1 to 3 feet of hydraulic fuid in the reverse-flow direction. This arrangement
shall be maintained at a temperature not wrmer than -65F for 4 hours. After this period,
the valve poppet shall be actuated mechanically at least 10 times. After the tenth
actuation, a Qualification test for leakage (4.4.5) shall be made at -65F and the require-
ments therein shall be satisfied. After this leakage test, the Control force test
specified herein under Acceptance (4.6.4), followed by the Operational tests (Cracking
pressure and Checking time (4.4.6)) shall each be performed at -650F, and the requirements
therein shall be satisfied.
4.4.8.2
Rapid warmup - The low temperature arrangement shall be allowed to warm
rapidly to a temperature of 27F. While the temperature is being raised, sufficient
mechanical actuation of the poppet and control movement shall be made at approximately
70F differntials in ambient temperature to determine satisfactory operation throughout
the temperature range. Tnese check tests shall be made without waiting for the temperature
of the entire unit to stabilize.
4.4.8.3
High temperature functioning - Except where otherwise indicated} the
following tests shall be conducted at a temperature of 275F. With a head of 1 to 3
feet of hydraulic fluid on the valve in the reverse-flow direction, the poppet shall be
actuated mechanically at least 10 times. After the tenth actuation, the Qualification
test for leakage (4.4.5) shall be conducted, and the requirements therein shall be
satsified. After this leakage test, the Control force test specified herein under
Acceptance (4.6.4) followed by Operational tests (Cracking pressure and Checking time
(4.4.6)) shall performed and the requirements therein shall be satisfied.
Endurance cycling - Controllablc check valves shall be subjected to a
4.4.9
total of 50,000 cycles of operation at a rate of 35 + 5
cpm. With a test setup similar
to figure 2, the valve shall be subjected first to 30,000 cycles of automatic checking
operation in the manner indicated in 4.4.9.1 and 4.4.9.2 Then with a test setup similar
to figire 3, the same valve shall be subjected to 20}000 cycles of manual control operation
in the manner indicated in 4.4.9.3 and 4.4.9.4. For automatic checking operation, each
cycle shall consist of free flow through the valve at the rated pressure and flow
capacity for the size, followed by an impulse in the reverse-flow direction of 150 percent
5 percent of rated pressure. Surge pressures in the free-flow direction during all
30,000 cycles of automatic checking operation shall be between 125 percent and 150 percent
of the rated pressure. For manual control operation, each cycle shall consist of first
opening and then closing the valve by means of the manual control, with the pressure
source delivering rated flow and pressure in the reverse-flow direction. For manual
control operation, surge pressure during the valve-closing portion of each of the 20,000
cycles shall be 150 percent + 5 percent of the rated pressure. The rated flow capacity
shall be as indicated in table IV.
8
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals