MIL-DTL-6396F
Alternate test methods may be used if approved by the procuring activity. A test apparatus
utilizing a grooved mounting flange with mating head in the retainer ring has been found to yield
more consistent results for some materials.
4.5.13 Fuel contamination.
4.5.13.1 Non-volatile gum residue. A 5-gram sample of the inner layers, up to the barrier,
shall be cut up into approximately 0.062 inch squares and placed in a flask containing 250
milliliter (ml) of test fuel conforming to ASTM-D471 Ref Fuel B, and allowed to stand for 48
hours at 77 ±5 °F (25 ±3 °C). The contaminated test fuel shall be decanted off and the non-
volatile gum residue determined by FED-STD-791, Method 3302, and ASTM-D381 except that
the total evaporation time shall be 45 minutes. The non-volatile material shall be not greater
than 60 milligrams (mg) per 100 ml of the contaminated fuel.
4.5.13.2 Stoved gum residue. The beakers containing the non-volatile material shall be
placed in an appropriate bath maintained constantly at a temperature of 572 ±9 °F (300 ±5 °C)
for 30 minutes. After cooling in a closed container, the beakers shall be weighed. The stoved
gum residue shall be not greater than 20 mg per 100 ml of the contaminated fuel, after necessary
corrections have been made for preformed gums originally present in the test fuel.
4.5.14 Oil dilution resistance. Tensile and elongation tests, before and after immersion in
the oil diluted 30 percent by volume with test fuel conforming to ASTM-D471 Ref Fuel B, shall
be made on the inner layer ply in accordance with ASTM-D412. The test specimens shall be
immersed for 48 hours at room temperature, 77 +5 °F (25 +3 °C). The tensile properties shall be
not less than 40 percent from the original values, and the Shore A durometer hardness shall vary
no greater than 15 points from the original value.
4.5.15 Inner liner strength.
4.5.15.1 Gum inner liner strength. The tensile strength of the gum inner layer ply, without
barrier, shall be determined in accordance with ASTM-D412, before and after immersion in
ASTM-D471 Ref Fuel B for 72 hours at a temperature of 135 ±3 °F (57 ±2 °C). The tensile
strength shall also be determined before and after immersion in a solution of 25 percent
MIL-DTL-85470 inhibitor and 75 percent water, by volume, for 72 hours at a temperature of
135 ±3 °F (57 ±2 °C). The tensile strength reduction shall be reported to the procuring activity.
The strength shall be reduced no greater than 50 percent for fuel immersion and 20 percent for
water immersion calculated on the basis of the original cross-sectional area.
4.5.15.2 Fabric inner liner strength. The tensile strength of the fabric inner layer ply,
without barrier, shall be determined in accordance with FED-STD-191, Method 5100 before and
after immersion in ASTM-D471 Ref Fuel B for 72 hours at a temperature of 135 ±3 °F
(57 ±2 °C). Also, the tensile strength shall be determined before and after immersion in a
solution of 25 percent MIL-DTL-85470 inhibitor and 75 percent water, by volume, for 72 hours
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