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

3.6 Solderability (when specified, see 3.1). When switches are tested as specified in 4.7.2, 95

percent of the total length of fillet, which is between the standard wrap wire and the terminal, shall be

tangent to the surface of the terminal being tested. There shall be no pinholes, voids, and so forth. A

ragged or interrupted line at the point of tangency between the fillet and the terminal under test shall be

considered a defect. After the test, there shall be no evidence of fracture, loosening of parts, or any other

mechanical failure of the switches.

3.7 Run-in (when specified, see 3.1 and 6.1). When switches are tested as specified in 4.7.3, the

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

3.8 Calibration (see 3.1 and 6.1).

3.8.1 Actuation and deactuation. When tested as specified in 4.7.4.1, switches shall actuate and

deactuate at the flow rate and pressure specified (see 3.1 and 6.1).

3.8.2 Proof flow. When tested as specified in 4.7.4.2, switches shall be capable of passing a

minimum proof flow with a maximum differential pressure (pressure drop) as specified (see 3.1 and 6.1).

3.8.3 Differential pressure (pressure drop through switches). When tested as specified in 4.7.4.3,

calibration and proof flow, the total pressure drop across the switch shall not exceed the specified values

(see 3.1 and 6.1).

3.8.4 Proof pressure. When tested as specified in 4.7.4.4, switches shall show no evidence of

leakage. Unless otherwise specified (see 3.1), the proof pressure shall be at least 150 percent of the

maximum operating pressure. The actuation and deactuation flow rate, measured before and after the

proof pressure test, shall not differ by more than the tolerances specified (see 3.1 and 6.1).

3.9 Transfer time. When switches are tested as specified in 4.7.5, the contacts of a pole shall

transfer within 5 milliseconds on both increasing and decreasing flow within the operating tolerances

specified (see 3.1 and 6.1).

3.10 Coincidence of operating points (applicable to multipole switches only). When switches are

tested as specified in 4.7.6, all poles shall transfer within a total operating time of 10 milliseconds on both

increasing and decreasing flow within the operating tolerances specified (see 3.1 and 6.1).

3.11 High temperature. When switches are tested as specified in 4.7.7, there shall be no evidence

of malfunction, internal leakage, deterioration, combustion, or any other damage that may adversely affect

the operation of the switch.

3.12 Low temperature. When switches are tested as specified in 4.7.8, there shall be no evidence

of malfunction, internal leakage, deterioration, combustion, or any other damage that may adversely affect

the operation of the switch.

3.13 Terminal strength (when specified, see 3.1). When switches are tested as specified in 4.7.9,

the terminals shall not break, loosen, crack, or affect the operation of the switch.

3.14 Connector torque (when specified, see 3.1). When switches are tested as specified in 4.7.10,

there shall be no loosening, rotation, distention, short circuiting, open circuiting, or other damage of any

portion of the connector-switch interface or switch itself.