MIL-DTL-87255A(USAF)
4.5.12 Centrifuge testing.
Centrifuge testing shall be conducted at a facility approved by the Government. The following
shall be capable of being recorded.
a. Gz: 1 to 10 G with an accuracy of ±0.1 G
b. Tank or anti-g suit pressure: 0 to 15 psig, with an accuracy of ±0.1 psig
c. Valve outlet pressure: 0 to 15 psig, with an accuracy of ±0.1 psi
d. Source pressure: 0 to 300 psig, with an accuracy of ±10 psig
4.5.12.1 Sampling rates and calibrations.
The sampling rates and calibrations shall ensure compliance with the performance requirements
of this specification. Both pre-test and post-test calibrations shall be required. The valve shall
be mounted in radial line with the accelerometer, and connected in accordance with 4.4.4.2 to a
for set-up.
4.5.12.2 Tests.
The following tests shall be performed:
4.5.12.2.1
Test profile 1.
With the valve inlet pressure maintained at 30 psig, the centrifuge shall be accelerated from 1.2
Gz to 10 Gz, held at 10 Gz for at least 10 seconds, and then decelerated back to 1.2 Gz. The
acceleration and deceleration (onset/offset) rates shall be 0.1 Gz per sec. This shall be as
shown on figure 8. Gz level at pressure initiation, the valve outlet pressure versus Gz level, and
The test shall then be repeated for a 4 Gz per sec onset/offset rate. The above test, at both
onset/offset rates, shall be repeated for 70, 150 and 300 psig valve inlet pressures.
4.5.12.2.2
Test profile 2.
The valve inlet pressure shall be maintained at 30 psig while the centrifuge is incrementally
accelerated from 1.2 Gz to Gz levels of 2, 4, 6, 8 and 10 at an onset rate of 4 Gz per sec. Each
Gz level shall be maintained for 10 seconds. It shall then be incrementally decelerated to 8, 6,
4, 2, and 1.2 Gz at a rate of 4 Gz per sec with 10 seconds at each level. This shall be as shown
specification. The above tests shall then be repeated with inlet pressures of 70, 150 and 300
psig.
4.5.12.2.3
Rotated mounting.
Mount the test valve so that the direction of valve's acceleration sensor shall be 22 degrees
from the direction of the applied acceleration, in the direction of the applied acceleration, in the
direction of the relief valve (see figure 10). With the inlet pressure at 70 psig, accelerate the test
valve at an onset rate of 0.1 Gz per sec, to 6 G's, hold at this level for 10 sec, and decelerate at
an offset rate of 0.1 Gz per sec to normal gravity. The valve outlet pressure, with respect to the
acceleration in the direction of the acceleration sensor, shall be as specified in 3.5.2. The valve
acceleration shall be determined by multiplying the actual acceleration by Cosine (22°).
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