MIL-DTL-28788 Switches, Air And Liquid Flow, Sensing, General Specification ForThis specification covers the general requirements for flow switches intended primarily for use in equipment to sense velocity and flow of air or liquid.

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MIL-DTL-28788C

3.15 Shock. Unless otherwise specified (see 3.1 and 6.1), when switches are tested as specified

in 4.7.11, there shall be no change in operation, no evidence of broken, deformed, displace, or loose

parts, and the operating points shall be within the tolerances specified (see 3.1).

3.15.1 Method I (shock, specified pulse). When switches are tested as specified in 4.7.11.1, closing

of open contacts and chatter of closed contacts shall not exceed 10 microseconds, unless otherwise

specified (see 3.1 and 6.1).

3.15.2 Method II (when specified, see 3.1) (high-impact shock). When switches are tested as

specified in 4.7.11.2, closing of open contacts and chatter of closed contacts shall not exceed 20

milliseconds, unless otherwise specified (see 3.1 and 6.2).

3.16 Vibration. When switches are tested as specified in 4.7.12, there shall be no opening of

closed contacts, nor closing of open contacts, in excess of 250 broken, deformed, displace, or loose parts

and the operating points shall be within the tolerances specified (see 3.1).

3.17 Thermal shock. When switches are tested as specified in 4.7.13, there shall be no mechanical

or electrical damage.

3.18 Moisture resistance. When switches are tested as specified in 4.7.14, the insulation

resistance immediately after conclusion of the test shall be greater than 2 megohms at 500 Vdc. At the

end of the drying period, the insulation resistance shall be as specified in 3.19. At the conclusion of the

test, there shall be no evidence of corrosion or mechanical damage.

3.19 Insulation resistance. When measured as specified in 4.7.15, the insulation resistance

between all insulated terminals and enclosures shall be not less than 500 megohms.

3.20 Dielectric withstanding voltage. Unless otherwise specified (see 3.1 and 6.1), when

switches are tested as specified in 4.7.16, there shall be no flashover, arcing, or current flow in excess of

500 microamperes.

Seal (when specified, see 3.1 and 6.2).

3.21

3.21.1 Watertight. When switches are tested as specified in 4.7.17.1, there shall be no leakage as

evidenced by a continuous stream of bubbles.

3.21.2 Hermetic. When switches are tested as specified in 4.7.17.2, the leakage rate shall not

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exceed 1x10 standard atmospheric cubic centimeters per second (atm cc/sec).

3.22 Contact resistance. When switches are tested as specified in 4.7.18, the initial resistance

shall not exceed 100 milliohms. The final resistance at completion of endurance testing shall not exceed

250 milliohms.

3.23 Endurance. When tested as specified in 4.7.19, there shall be no evidence of malfunction or

damage during or after the test, and switches shall meet the requirements of 3.8.

3.24 Sand and dust (when specified, see 3.1). When switches are tested as specified in 4.7.20, the

subsequent operating characteristics shall be as specified (see 3.1), and they shall be mechanically and

electrically operative at the conclusion of the test.

3.25 Explosion (when specified, see 3.1). When switches are tested as specified in 4.7.21, there

shall be no explosion within the test chamber, whether or not explosion occurs within the switch.

Switches shall be mechanically and electrically operable at the conclusion of the test.