MIL-DTL-26521L
4.5.3 Individual test failures. Any item failing to meet the requirements of the individual tests shall be
immediately removed from the lot. The entire lot shall be inspected for that particular defect and then the
entire lot shall be re-inspected from the point where the failure occurred. Any additional hose assembly
failing to meet the requirements of the individual inspections specified in table V, the entire lot shall be
rejected and not supplied to the contract.
4.6 Performance requirements.
4.6.1 Hose liner test methods.
4.6.1.1 Liner thickness (see 3.5.2.1). The liner thickness dimensions shall be measured in
accordance with ASTM D380 and meet the requirements of 3.5.1.2.
4.6.1.2 Liner tensile strength and elongation (see 3.5.1.3). The liner material tensile strength and
elongation shall be tested in accordance with ASTM D380 and ASTM D412 and meet the requirements of
4.6.1.3 Liner volume change (see 3.5.1.4). The liner material volume change shall be tested in
accordance with ASTM D380 and ASTM D471 and meet the requirements of 3.5.1.4. The following shall
apply, the liner material shall be immersed for 70 hours in ASTM D471 reference fuel B at 72°F ±2°F
(22°C ± 1.1°C).
4.6.1.4 Liner extractable material (see 3.5.1.5). The fuel-soluble matter test shall be performed
based on ASTM D2276, the following details shall apply:
a. A sample of hose liner shall be cut into pieces of approximately .12 in2.
b. 5 ± .01 grams of the sample shall be extracted into 100 ml of reference fuel B in accordance
with ASTM D471.
c. The test fluid and sample shall be stored in a glass flask for 96 hours at 104°F ±2° F (38°C ±
1.1°C). Suitable precaution should be taken to prevent loss by evaporation.
d. The flask contents shall be filtered into a pre-weighed hemispherical glass dish of suitable
size, while washing both the residue in the flask and the filter with a further quantity of fuel.
e. The contents of the dish shall be evaporated on a boiling water bath and the residue shall be
heated in a ventilated air oven for 2 hours at 302°F ± 5°F (150°C ± 2.7°C).
f. The weight of the extractable residual matter shall be calculated as a percentage of the original
test sample weight. The percentage of extractable residual matter shall not exceed the limit
specified in 3.5.1.5.
4.6.1.5 Liner fuel contamination (see 3.5.1.6). The liner material when tested for fuel contamination
shall meet the requirements of 3.5.1.6, the following details shall apply:
a.
Sample shall be a 3 inch diameter 12 inch long (76.2 mm diameter 305 mm long) hose.
b.
The liner material shall be extracted with ASTM D471 reference fuel B.
c.
The sample shall be plugged at one end with a glass or non-contaminating metal plug.
d.
The hose sample shall be filled with reference fuel B specified in ASTM D471 and shall be
allowed to stand for three days at 72°F ±2°F (22°C ±1.1°C).
e. The hose sample shall be drained and refilled with fresh ASTM D471 fuel B.
f. The procedure shall be repeated daily for four additional days.
g. On the eighth day the hose sample shall be drained and refilled with fresh ASTM D471
reference fuel B and shall be allowed to stand for three additional days at 72°F ±2°F (22°C ±
1.1°C).
h. On the final cycle, the fuel from the sample hose shall be tested in accordance with
ASTM D2276.
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