MIL-DTL-87255 Valves, Pressure, Anti-G Suit, High FlowThis specification covers a high-flow, pressure regulating valve for inflating anti-G suits and providing a sense line signal for a g-compensated oxygen regulator \(if applicable\). It also includes details of inlet and outlet fittings required to interface the valve to specific aircraft.

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MIL-DTL-87255A(USAF)

4.5.9

Vibration

4.5.9.1 Random vibration.

With the valve connected to the test equipment described in 4.4.4, with an inlet pressure of 300

psig, the valve shall be exposed for one hour at each simulated G level to the random vibration

described below in each of three mutually orthogonal axes. After this test, there shall be no

damage to the valve and the valve performance shall be verified as described by 4.5.2 through

4.5.6, except that the minimum operating force can be between 1.25 and 2.0 Gz. The random

vibration envelope (see figure 6) shall be as follows:

0.04 g2/Hz from 15 � 100 Hz

-4 db/octave slope from 100 � 140 Hz

0.025 g2/Hz from 140 � 540 Hz

0.072 g2/Hz from 540 � 900 Hz

-6 db/octave from 900 � 2000 Hz

4.5.9.2 Resonance.

With the test equipment and anti-g valve set up as described in 4.5.9.1, and using a sinusoidal

vibration at 0.02 inches or �2 Gz double amplitude whichever shall be less; a resonance search

shall be conducted between 5 and 2000 Hz in three mutually orthogonal axes to identify

resonant frequencies. The valve shall then be subjected to any and all resonant frequencies for

seven and one half minutes each. There shall be no damage to the valve and the valve shall

meet the requirements of 3.5.1 through 3.5.5 before and after this exposure. After this test,

there shall be no damage to the valve and the valve performance shall be verified as described

by 4.5.2 through 4.5.6, except that the minimum operating force can be between 1.25 and 2.0

Gz.

4.5.9.3 Gunfire vibration.

With the test equipment and anti-g valve operating as described in 4.5.9.1, the valve shall be

subjected to the following vibrations along each of three mutually orthogonal axes. After this

test, there shall be no damage to the valve and the valve performance shall be verified as

described by 4.5.2 through 4.5.6, except that the minimum operating force can be between 1.25

and 2.0 Gz.

4.5.9.3.1

Excitation.

The excitation shall consist of four phase uncorrelated sinusoids superimposed over a random

vibration background. The sinusoids shall be at frequencies representing the basic gunfire rate

orders; 100 Hz (f1), 200 Hz (f2), 300 Hz (f3), and 400 Hz (f4). Synchronously, the frequencies

shall be swept logarithmically over a bandwidth equal to �0.2 times f1 f2, f3, and f4, beginning at

the low frequency and ending at the high frequency limit. The sweep time for the combination

sine sweep and random vibration shall be 60 minutes per axis. The instantaneous peaks of the

random vibration may be limited to 2.5 times the root mean square spectral acceleration level.

Spectrum frequencies, frequency-function levels, and location-function levels for the combined

random and sinusoidal vibration tests shall be as contained on figure 7. After this test, there

shall be no damage to the valve and the valve performance shall be verified as described in

4.5.2 through 4.5.6, except that the minimum operating force can be between 1.25 and 2.0 Gz.