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|  MIL-S-25980A(USAF)
4 . 6 . 4 Leakage.- The float switch shall be Installed on a pressure vessel
a n d the vessel filled w i t h teat fluid. The vessel shall be positioned in such
manner that the float switch mounting seal is in contact with the test fluid at all
times. A pressure Of 30 psi shall be applied to the test fluid, Any leakage
occurring irlth.in a 10-minute waiting periods commencing with the application-of pres-
sue, shall constitute failure. Float switches designed for mounting within q fuel
tank shall also be subjected to 30 pal test fluid pressure for a 10-minute period.
Any evidence of leakage into the sealed portions of the float switch, as disclosed
by disassembly and inspection on completion of all tests, shall constitute failure.
4.6.5 Proof pressure.- The float switch shall be installed on a pressure
vessel and the vessel filled with test fluid. The vessel shall be positioned in
such manner that the float switch mounting seal is in contact with the test fluid
at all times. A pressure of 60 psi shall be applied to the teat fluid for a 5-
minute period. When the pressure is reduced to 30 psi, there shall be no external
leakage during q 10-minute waiting period. There shall be no evidence of failure,
malfunction, or distortion, and the low specific gravity teat shall be performed in
accordance with 4.6.3.1, This test also applies to float switches designed for
mounting within fuel tanks.
4.6.6 Burst pressure.- The float switch shall be installed on a pressure
vessel and the vessel filled with teat fluid. The vessel shall be positioned in
such manner that the float switch mounting seal is in contact with the test fluid
a t all times. A pressure of 90 psi shall be applied to the test fluid for a 5-
minute period. When the pressure is reduced to 30 psi, there shall be no external
leakage during a 10-minute waiting period. The float switch shall be functionally
operational when tested with the low specific gravity test as described in 4.6.3.1.
This test also applies to float switches designed for mounting within fuel tanks.
4.6.7 Vibration.- The float switch shall be subjected to vibration test Prroce-
dure XII of MIL-E-5272. Half of the total vibration period shall be conducted with
the switch assembly in the dry state. The cycling times, resonant scanning, and
prolonged vibration shall all be proportioned between a condition of operation and
a condition of nonoperation. The maximum rated resistance load shall be contin-
uously monitored by means of an oscilloscope for any erratic or inadvertent opera-
tion during vibration. Float switches with relays shall be tested, using minimum
line voltage applied to the relay. The test fluid level shall be maintained within
the actuation range of the float switch. Any erratic or inadvertent operation
during teat or any evidence of failure or distortion shall constitute failure. On
completion of teat, the low specific gravity teat shall be performed in accordance
w i t h 4.6.3.1.
4.6.8 Fungus resistance The float switch shall be subjected to fungus
resistance test Procedure I of MIL-E-5272. After completion of the test, the
complete float switch shall be subjected to the low specific gravity test in
accordance with 4.6.3.1.
The float switch shall be subjected to humidity test Proce-
4.6.9 Humidity.-
dure I of MIL-E-5272. There shall be no evidence of malfunction or deterioration
that might adversely affect operation. At the end of the test period, the low
specific gravity test shall be performed in accordance with 4.6.3.1.
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