MIL-DTL-24643C
4.8.11 Drip. This test shall determine whether or not fillers will exude and drip from the cable ends when
cables containing these fillers are subjected to high temperatures. Such filler dripping may produce deleterious
effects, such as the coating or bridging of underlying electrical contacts.
4.8.11.1 Specimen. The specimen shall consist of an 18±½ inch length of completed cable.
4.8.11.2 Special apparatus. Apparatus shall include a heating chamber for supporting the requirements as
specified in 4.8.11.3. The chamber air temperature shall be measured in the immediate vicinity of the specimen.
4.8.11.3 Procedure. The specimen shall be straightened and shall be suspended from one end within the
heating chamber, such that the specimen hangs freely downward. The temperature within the chamber shall then be
raised to the specified value (see 3.1) within 1 °C. This chamber temperature shall be maintained for a continuous
period of not less than 18 hours. Provision shall be made to catch any material which may fall away from the lower
specimen end during this test.
4.8.11.4 Observation. Specimen failure shall be construed if any material falls away from the lower specimen
end during the test.
4.8.12 Durometer hardness. This test shall be to determine whether or not jacketing material exhibits
sufficient hardness (see 4.8.12.4) for use in cable construction.
4.8.12.1 Specimen. The specimen shall consist of a block of material of the dimensions specified in
ASTM D2240, which shall have been cured in effectively the same manner as when used in cable manufacture.
4.8.12.2 Special apparatus. Apparatus shall include a Type A or D durometer, as specified (see 3.1), which
shall be in accordance with ASTM D2240.
4.8.12.3 Procedure. The specimen shall be tested in accordance with ASTM D2240.
4.8.12.4 Observation. Specimen failure shall be construed if the specimen exhibits a durometer hardness other
than that specified (see 3.1).
4.8.13 Flame propagation. This test shall be to determine the relative ability of grouped cable to resist the
propagation of fire along its length. The test shall be performed according to Method 1 of UL Standard 1685,
without the smoke requirements.
4.8.14 Gas flame. This test shall determine the ability of completed cable to maintain electrical circuit integrity
in the presence of flame.
4.8.14.1 Specimen. The specimen shall consist of a 48±6 inch length of completed cable. The jacket and
blocking materials shall be removed for a distance of 3 inches on each end of the sample. Sufficient insulation shall
be removed from one end of each conductor for making electrical connections as follows:
a. Specimens with one conductor shall be tested with single-phase voltage. The specimen shall be covered
with an aluminum or copper braid shield providing no less than 50 percent coverage. The braid covering shall be
attached to ground.
b.
Specimens with two conductors shall be tested using two phases of the three-phase source.
c.
Specimens with three conductors shall be tested with each conductor connected to a separate phase.
d. Specimens with four conductors shall have physically opposite conductors and be connected together in
pairs to form two effective electrical circuits.
e. Specimens with six conductors shall have physically opposite conductors and be connected together in
pairs to form three effective electrical circuits.
f. Specimens with seven or more conductors shall have conductors connected together to form three effective
electrical conductors. Connections shall be made such that physically adjacent conductors shall be members of
different effective electrical conductors to the maximum practicable extent and such that the number of conductors
constituting each effective electrical conductor does not differ by more than one.
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