MIL-PRF-24758A(SH)
3.7 Conduit/conduit fitting integrity. Conduits when bent or compressed, exposed to vibrations (see 6.3.19),
or when exposed to extreme specified temperatures, shall maintain the following properties.
Compression. Conduits, when bent or banded, shall not compress by more than 10% of the conduit
3.7.1
initial inside diameter (ID) when subjected to a compression force of 168.60 pounds (lbs) (750 newtons (N)).
Impact. The conduit system shall maintain performance requirements for electrical, electromagnetic,
3.7.2
and weatherproofing properties when subjected to 14.75 ft/lbs (20 joules) of blunt impact energy with a fall height
of 12 inches plus or minus .25 inches (304mm plus or minus 6 mm).
Vibration. The conduit system shall remain intact and the end fittings are to remain torqued to the
3.7.3
manufacturer's specification when tested in accordance with paragraph 4.7.3.
Tensile strength. A complete conduit system with two terminating fittings shall show no damage nor
3.7.4
have fittings become loosened when subjected to a tensile force of 224.80 lbs (1000 N).
Flexing. A conduit system with a terminating fitting, assembled according to the manufacturer's
3.7.5
instructions, shall have no visible structural damage after two hundred flexings of 120 degrees, at the rate of 20
flexings per minute (min) at each of the temperature limits: -40 °F (-40 °C) to +257 °F (+125 °C). (see 3.4.1) 120°
is understood to mean 60° each side of the longitudinal axis.
Resistance to heat. The conduit shall demonstrate resistance to heat at 257 °F (125 °C) and not be
3.7.6
depressed under load for the relevant conduit. Conduit fittings and constituent parts shall demonstrate resistance to
heat at 257 °F (125 °C) and not dimple under load.
Resistance to flame-propagation. Conduits shall demonstrate resistance to flame-propagation.
3.7.7
Acid gas emission. Conduit systems shall be halogen free (see 6.3.14). The level of acid gas evolved
3.7.8
by conduits calculated as hydrochloric shall be not greater than .0001764 ounce (oz) (5 milligrams (mg)) of
hydrochloric acid per gram of sample.
Shock. Conduit systems shall maintain performance requirements for electrical/electromagnetic
3.7.9
properties and watertight integrity when subjected to nine hammer blows from a medium weight shock machine.
3.8 Weatherproofing. The conduit system shall be inherently weatherproof from end fitting to end fitting.
The conduit system, with the ends of both terminating fittings plugged, shall allow no ingress of water when
subjected to a water jet of 26.42 gallon (100 liters)/min ±5%, from a .49-inch (12.5-mm) diameter nozzle at a
distance of 8.20 to 9.84 feet (2.5 to 3 meters) for 3 minutes.
3.9 External corrosion. Conduit systems shall be constructed of materials that provide external corrosion
protection. Conduit systems shall show no evidence of corrosion when subjected to a cyclic sulfur dioxide/salt fog
(SO2/NaCl) test.
Corrosion and polluting substances. Conduit systems shall demonstrate a high degree of protection
3.9.1
against corrosion, both outside and inside, when flexed to the minimum bend radius of 8 times the conduit's outside
diameter (OD).
Solar radiation. The conduit system shall not degrade in electrical or mechanical performance due to
3.9.2
exposure to 10 cycles of solar radiation. The conduit shall be resistant to solar radiation as defined in 3.4.3.
3.10 EM signal attenuation. EM signal attenuation over a frequency range of 100 KHz to 600 MHz for a
conduit system shall not exceed a surface transfer impedance of 100 milliohms per meter.
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