MIL-DTL-3950J
4.8.19 Switch sealing (see 3.6.18).
4.8.19.1 Sealing.
a. Applicable for qualification and group B tests only. Switches shall be immersed in an enclosure
containing a saturated solution of sodium chloride. The enclosure shall be subjected to a vacuum
resulting in an absolute pressure of 2.0 inches ± 0.5 inches of mercury. During the first 5 minutes
after the required vacuum has reached, the immersed switches shall be observed for leakage as
evidenced by a continuous stream of bubbles emanating from the switch case. The vacuum shall
be maintained for a period of 4 hours, and the pressure shall then be returned to normal. After
immersion for a minimum of 16 hours at normal pressure, the switches shall be removed from the
enclosure, and the odd-numbered specimens shall be opened and examined for leakage at the
conclusion of the test sequence. "Switches with integrated wire termination shall be fully wired
and shall have one inboard and one outboard terminal on two switches loaded with a five-pound
±1 pound load at 90° to the center line of the switches."
b. Applicable for group A tests only. The switches shall be immersed in an enclosure containing
water. The enclosure shall be subject to a vacuum resulting in an absolute pressure equal to
2 inches ± 0.5 inches of mercury for 5 minutes. The immersed switches shall be observed for
leakage as evidence by a continuous stream of bubbles emanating from the water prior to
release of the vacuum.
4.8.19.2 Terminal sealing, fluid submersion (applicable to switches with integrated wire terminals).
a. Applicable to qualification and group B only. Switch terminals shall be immersed for three cycles
as follows:
(1) Two switches (specimen 1 and specimen 2 of table II) with integrated wire terminals shall be
fully wired.
(2) Switches shall be completely submerged in each of the following fluids for 2 (+1/2, -0)
minutes which shall consist on one cycle:
(a) MIL-DTL-83133 Turbine Fuels, Aviation, Kerosene Types, NATO F-34(JP-8), NATO F-
35, and JP-8 + 100 or Commercial Jet-A-1.
(b) Skydrol 500 A - Federal Stock Number 9150-857-9069.
(c) MIL-PRF-87252 - Coolant Fluid, Hydrolytically Stable, Dielectric.
(d) ASTM E 1119 - ethylene glycol.
(e) MIL-PRF-7808 - Lubricating Oil, Aircraft Turbine Engine, Synthetic Base.
(f) After each immersion the excess liquid is to be blown off the switch external surfaces with
an air jet.
(3) At the end of the third cycle, the dielectric withstanding voltage shall be as specified herein.
There shall be no cracking and loosening of bonds and seams.
(4) Switches shall be operable and the odd-numbered samples shall be opened and examined
for leakage upon conclusion of the test sequence.
5. PACKAGING
5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the
contract or order (see 6.2). When packaging of materiel is to be performed by DoD or in-house contractor
personnel, these personnel need to contact the responsible packaging activity to ascertain packaging
requirements. Packaging requirements are maintained by the Inventory Control Point's packaging
activities within the Military Service or Defense Agency, or within the military service's system commands.
Packaging data retrieval is available from the managing Military Department's or Defense Agency's
automated packaging files, CD-ROM products, or by contacting the responsible packaging activity.
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