MIL-PRF-131K
4.6.2.2 Procedure. A water solution, containing dye and 1 percent sodium
dioctylsulfosuccinate as approved by the qualifying activity, shall be made to produce a distinct
color. The solution shall be poured into each sealed pouch to a level of two inches above the top
of the bottom seam. The pouches shall then be suspended vertically. After a period of 15
minutes at room temperature, the pouches shall be examined for dye leakage at all seams and
especially at the double seam junctions (the points where the vertical seams intersect the bottom
seam at points other than at the corners of the pouch) by blotting with white tissue.
4.6.3 Aging resistance. Three specimens, 36 by 6 inches, cut from across the roll of
material, at points which shall be not less than 1 yard apart, shall be used for this test.
4.6.3.1 Procedure. The specimens shall be subjected to the following aging cycle:
8 hours in a humidity chamber of 100 ± 2 °F and 90 to 95 percent relative humidity.
16 hours in a circulating air oven at 160 ± 2 °F.
The aging cycle shall be repeated every weekday, for five consecutive days. The specimens shall
remain in the circulating air oven maintained at the conditions described above on Saturday,
Sunday and holidays, except that holidays shall not exceed a total of two days over the entire
aging period. The aging procedure shall continue for fourteen consecutive days. The specimens
shall be folded loosely, hung, rolled loosely or laid flat in the test chamber during the aging
period. At the conclusion of the aging period the specimens shall be returned to room
temperature and examined, particularly at all edges, for delamination brought about by the aging
exposure. No supplemental attempt to delaminate the material, such as prying or picking at the
plies, shall be carried out. Delamination shall be measured as ply separation at any one given
point extending more than ½ inch from the edge, with an edge length separation greater than one
inch.
4.6.4 WVTR (modulated infrared sensor). A suitably sized sample of material shall be
installed on a calibrated device for measuring moisture permeation through an area of
approximately 50 cm2 in accordance with ASTM-F1249. The surface of the sample designed for
heat sealing shall be oriented toward the dry carrier gas with the other side oriented toward a
100 percent relative humidity environment. The test temperature shall be 100 °F (38 °C). The
material shall be tested for permeation, allowing a minimum of 80 hours to reach steady state.
Three samples shall be tested and the results averaged.
4.6.5 Breaking strength. Five specimens 4 by 6 inches shall be cut with the long dimension
parallel to the machine direction and another five specimens of the same size cut in the transverse
direction. Specimens shall be marked with a line parallel to a long edge and 1½ inches from it.
Clamps shall be rubber-faced pneumatic grips with the gripping surface 1 by 1 inch. Initial grip
separation shall be 2 ± ½ inches. Each specimen shall be installed by aligning the marked line
with the inside edge of the grips, allowing approximately the same amount of material protruding
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