MIL-DTL-24487B (SH)
4.5.3 Hardness. The hardness of the tiles shall be measured with a durometer conforming to ASTM D
2240, Type A.
4.5.3.1 Reference value. Hardness shall be determined on each of the five tiles furnished for first article
inspection and the results shall be averaged. This average value shall be recorded as a requirement for conformance
tests of tiles submitted for delivery by the same contractor.
4.5.3.2 Conformance. For conformance tests, hardness shall be determined on each tile selected in 4.4.2.
The values obtained on each tile shall be averaged and compared to the average obtained in 4.5.3.1 and shall
conform to the requirement in 3.2 within ± 5 units.
4.5.4 Tensile strength and ultimate elongation. Die C specimens shall be used. The specimens shall
conform to 3.2.
4.5.4.1 Initial tensile strength and ultimate elongation. The tensile strength and ultimate elongation of the
0.080 inch (0.203 cm) thick specimens representing the rubber tiles shall be determined in accordance with ASTM
D 573 and ASTM D 412.
4.5.4.2 Tensile strength and ultimate elongation after oven aging. The tensile strength and ultimate
elongation of the 0.080 inch (0.203 cm) thick specimens representing the rubber tiles shall be determined after oven
aging for 166 ± 2 hours at 158 ± 2 °F (70 ± 1.1 °C) in accordance with ASTM D 573 and ASTM D 412.
4.5.5 Flame retardance. Flame retardance shall be determined in accordance with ASTM D 635, except
that no wire gauze shall be mounted beneath the specimen and only three specimens cut from the same tile shall be
tested. Each of the three specimens shall be rated at least self-extinguishing. If a specimen does not burn to the 4-
inch mark after the first or second ignition, it is judged to be "self-extinguishing".
4.5.6 Volume change after immersion in water. Three specimens, each 1 by 2 by 0.080 ± 0.010 inches
(2.5 by 5.1 by 0.20 ± 0.025 cm) prepared from sheets furnished in 4.3.1 or 4.3.3 shall be immersed in distilled water
in accordance with ASTM D 471 at a temperature of 130 ± 2 °F (54.4 ± 1.1 °C) for a period of 166 ± 1 hour. The
resulting change in volume of each specimen shall be determined by and the results shall be averaged. The volume
change shall conform to the requirement in 3.2.
4.5.7 Adhesion of tile to painted steel surface.
4.5.7.1 Specimen preparation. Three specimens each 1 by 11.875 inches (2.5 by 30.16 cm), shall be cut
from one of the tiles along the grooves. The edge of the tile shall not be used for adhesion specimens. The rubber
specimens shall be cleaned on the grooved side with PF-145HP degreaser (also known as PF High Performance
Solvent, available from PT Technologies, 4647 Hugh Howell Road, Tucker, Georgia 30084) and allowed to dry.
The grooved side of each specimen shall be bonded to a steel plate prepared to SSPC-SP 10 and painted with
MIL-DTL-24441/29 to achieve a nominal dry film thickness (DFT) of 1 - 3 mils, approximately 2 by 14 by 0.125
inches (5.1 by 36 by 0.32 cm), using epoxy adhesive conforming to MIL-A-24456. The adhesive shall be mixed in
accordance with manufacturer's instructions and applied to the central portion of the steel plate which has been
previously masked to expose an area which fits the rubber specimen. The adhesive shall be applied evenly and be
0.10 ± 0.01 inch (0.25 ± 0.03 cm) thick. One end of the specimen shall be aligned on the steel plate. The opposite
end of the specimen shall be held up and a hand roller shall be used to draw the specimen against the steel surface.
The surface of the specimen shall be rolled several times to press it firmly against the steel surface. The excess
adhesive shall then be removed by stripping the masking tape before the adhesive sets. The assembly shall be
allowed to stand for at least 3 days at room temperature before testing.
4.5.7.2 Test procedure. The measurement shall be made at a 90-degree angle of pull. The assemblies
shall be immersed in salt water (3 percent sodium chloride) at room temperature and fastened in a horizontal
position with the specimen on the bottom side. One end of the specimen shall be peeled loose from the steel far
enough to permit the fastening of a clamp with weight equal to 25 pounds (11.3 kg) (corrected for buoyancy of the
salt water). Mark the starting point on the steel where the rubber is still just attached to the steel. The specimens
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