MIL-PRF-87260B(USAF)
reticulation prior to compression load deflection testing. Tests shall be conducted in the
direction of material rise. Prior to testing, the specimens shall be pre-flexed twice to 80 percent
compression. A copy of the recorded traces for each test shall be included in the test report
and results reported in pounds per square inch. For wet compression load deflection
properties, the test specimen shall be tested immediately after removal from the fluid. The
original dry specimen data shall be used as a baseline for determining the percent loss in wet
compression load deflection properties per 4.5.16b.
4.5.9 Fuel displacement test.
One sample per test shall be run using Grade JP-5 or JP-8 turbine fuel conforming to MIL-DTL-
5624 or MIL-DTL-83133 respectively, and the average reported as the fuel displacement. The
test shall be conducted at standard conditions using a standard 1,000 milliliters (ml) capacity
cylinder having 10 to 20 ml graduations. Each specimen shall be cut into a cylindrical shape
having a diameter approximately equal to that of the graduated cylinder and a length sufficient
to fill the test cylinder to the 900 ml mark. Specimens shall be cut in the direction of the material
rise (bun height). Fuel shall be added to the 900 ml mark in the graduated cylinder and the
specimen slowly added until it is completely immersed. The specimen shall be immersed for a
period of 24 hours to obtain maximum swelling effects. The new fluid level shall be noted and
the increase in milliliters shall be recorded. The size of each specimen shall be measured and
recorded. The displacement shall be calculated as follows:
m illilit er s in cr ease X 1 0 0
Per cen t v olu m e d isp lacem en t =
or ig in al f lu id v olu m e
4.5.9.1
Theoretical fuel displacement.
The theoretical volume displacement of the material as calculated from the following formula
and based on the material density specified in 4.5.3 shall be reported:
m at er ial d en sit y ( lb s/ f t 3 ) X 1 0 0
Per cen t v olu m e d isp lacem en t =
d en sit y of p oly m er s ( lb s/ f t 3 )
4.5.10 Fuel and water retention test.
4.5.10.1 Fuel retention tests.
Fuel retention shall be determined on a 6 inches x 6 inches x 6 inches specimen using Grade
JP-5 or JP-8 turbine fuel conforming to MIL-DTL-5624 or MIL-DTL-83133 respectively, having a
specific gravity of 0.788 to 0.845. For qualification testing the retention values shall be
determined throughout the porosity range of the product and the data plotted as a function of air
pressure drop. A minimum of three different retention specimens at three different porosity
locations (lower, middle, and upper porosity ranges) shall be tested for each type of material. At
each test location, four retention specimens shall be cut from the center of the respective test
section (bun height) directly adjacent to each other. These shall be identified at the top surface,
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