MIL-PRF-87260B(USAF)
within the porosity range for a material shall be evaluated and a curve of fuel retention versus
air pressure drop established. The data (curve) shall be extrapolated to the upper air pressure
drop limit and the projected fuel retention limit shall be established and reported. A fuel
retention sample for each data point along with the tested porosity samples shall be identified
and submitted to the qualifying activity (see 6.3.1).
4.5.11 Extractable material test.
The extractable material test shall be conducted on one test specimen. The specimen size shall
be 1 inch x 1 inch x 2 inches and cut by means of a saw or die. Preconditioning of the
specimen shall include drying at 200 ±5°F for 15 minutes and cooling the specimen in a
desiccator for a minimum of 30 minutes. Immediately following the preconditioning, the
specimen shall be weighed to the nearest 0.10 milligram. The specimen shall then be placed in
a 60 ml volume Soxhlet extraction tube which is connected to a water-jacketed condenser.
Several standard boiling stones and 125 ml of Type III test fluid conforming to SAE AMS-2629
shall be added to a 250 ml Florence flask and the flask attached to the extraction tube. The
heating unit shall be activated and the fluid allowed to reflux for a period of 3 hours. Following
reflux, the specimen shall be removed, dried at 200 ±5°F for 15 minutes, cooled in a desiccator
for 30 minutes and then weighed. The percentage of extractable material shall be calculated as
follows:
( or ig in al sp ecim en w eig h t - f in al w eig h t ) X 1 0 0
Per cen t ex t r act ab le =
or ig in al sp ecim en w eig h t
4.5.12 Volume swell test.
One specimen for each test fluid shall be tested for volume changes after immersion for 7 days
at 72 ±5°F in Type I test fluid conforming to SAE AMS-2629, Type III test fluid conforming to
SAE AMS-2629, and Grade JP-5 conforming to MIL-DTL-5624, and JP-8 turbine fuel
conforming to MIL-DTL-83133. Sample size shall be 6 inches x 6 inches x 6 inches. The
samples shall be taken from the same approximate location in the test section as the retention
test specimens specified in 4.5.10. Dry and wet measurements shall be made on the test
specimens in accordance with ASTM D3574. Following immersion, the specimens shall be
removed and immediately measured wet for the final volume. All values for the specimen
including original and wet volumes shall be reported and the percent volume increase from the
original and wet measurements shall be calculated.
4.5.13 Low temperature flexibility test.
Three specimens, 2 inches x 1/2 inch x 12 inches shall be preconditioned in air along with a
3-inch diameter rod to a temperature of -55 ±5°F for 1 hour. Each specimen shall be cut such
that the 12-inch dimension is in the machine direction. At the end of the conditioning period and
without removing the specimens from the chamber, each specimen shall be bent around the
rod. Any evidence of breaking or cracking of foam strands shall be cause for failure.
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