MIL-DTL-28788C
202. The following details and exception shall apply.
a. Number of terminations for each part to be tested Two.
b. Dipping device If it cannot be used, immersion, dwell, and emersion times shall be as
specified.
c. Examination of terminations Method for evaluation of lugs and tabs shall apply.
4.7.3 Run-in (see 3.7). Switches shall be mounted by their normal mounting means in equipment
capable of providing the media at the flow rates specified (see 3.1). The switches shall be cycled for the
number of cycles specified (see 3.1). One cycle shall consist of increasing the flow rate from 0.25 gallon
per minute (GPM) or 20 percent below the minimum operating flow rate, whichever is less, to the
actuation point and back to the initial flow rate.
4.7.4 Calibration (see 3.8).
4.7.4.1 Actuation and deactuation (see 3.8.1). Switches shall be mounted by their normal mounting
means in equipment capable of providing the media at the flow rates and pressure specified (see 3.1).
The flow rate shall be increased to within 10 percent of actuation and then increased at a flow rate
gradient, not exceeding 1 percent per second, until the actuation point is reached. The point shall be
recorded. The flow rate shall then be reduced to within 10 percent of deactuation and then decreased at
a flow rate gradient, not exceeding 1 percent per second, until deactuation occurs. The value shall be
recorded. The flow rate shall then be decreased to zero. Media other than the service media may be
used during these tests if the changes in fluid properties are properly correlated and submitted for
approval to the qualifying activity.
4.7.4.2 Proof flow (see 3.8.2). Switches shall be mounted in the same fixture and system utilized for
calibration (see 3.8). The flow shall be increased to the proof flow value specified (see 3.1 and 6.1), and
maintained for 1 minute. Proof flow may be run in conjunction with calibration (see 4.7.4.1).
4.7.4.3 Differential pressure (see 3.8.3). Switches shall be mounted in the same fixture and system
utilized for calibration (see 3.8.1). The differential pressure (pressure drop) measurements shall be taken
in conjunction with calibration, at actuation flow, system flow and deactuation flow. During proof flow,
differential pressure will be measured at the specified proof flow value (see 3.1 and 6.1). A differential
pressure gage of at least 0.1 pounds per square inch (PSI) accuracy, shall be mounted such that it
senses the pressure drop across (through) the switch, during flow conditions. The pressure pick-off
points shall be as specified on figure 1.
4.7.4.4 Proof pressure (see 3.8.4). Switches shall be connected to equipment capable of supplying
the specified medium at the pressure which can be varied from zero to at least the proof pressure
specified (see 3.1). The downstream side of the switch may be closed. The pressure, either static or
dynamic, shall be increased from zero to the specified proof pressure, maintained 1 minute, and
decreased to zero.
4.7.5 Transfer time (see 3.9). Switches shall be tested using a variable flow which shall be
increased and decreased slowly and uniformly, with no external vibratory influence while passing through
the operating points at a rate of change not exceeding 1 percent per second.
4.7.6 Coincidence of operating points (see 3.10). When switches are tested, the variable flow shall
be increased and decreased slowly and uniformly, with no external vibratory influence while passing
through the operating points, at a rate of change not exceeding 1 percent per second. All poles shall
transfer contacts on both increasing and decreasing flow tolerances specified (see 3.1 and 6.1), within a
total operating time of 5 milliseconds.
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