MIL-PRF-20092M
pressure heat aging and low temperature compression resistance. The air-pressure heat-aging test shall be
performed by the contractor on the first lot; subsequent testing will be performed by the Government as necessary.
4.5 End item testing. Testing of the completely fabricated item taken from the production line shall be
performed as specified in Table III for the characteristics shown therein. The sample size shall be as specified in
4.3.4. Tests shall be conducted in accordance with applicable methods as specified. Unless otherwise specified
(see 6.2), tests shall be conducted at a temperature of 70 + 5 degrees Fahrenheit (°F). Specimens shall be
conditioned in an atmosphere of 50 + 45 percent relative humidity, and a temperature of 73 + 4°F.
4.5.1 Indentation. The indentation of Type II mattress inserts shall be determined in accordance with
ASTM D 3574, Test B1 except that test specimens shall be not less than 15 by 15 by 3 inches and the values shall
be obtained 5 seconds after the pressure foot has produced a 25 percent indentation in the cellular material.
4.5.2 Density. Density or apparent density shall be determined by accurately weighing and measuring the
cellular sample and dividing the weight by the volume. The volume of irregular-shaped pieces shall be determined
as follows: The sample shall be placed in a graduated container and then completely surrounded by 10 to 14 mesh,
free flowing seed, such as flaxseed, so that the sample is covered to a depth of 1 inch. The true or apparent volume
(as applicable) of the seed plus the sample shall be noted, the sample removed, and the volume of the seed
determined. The volume of the sample shall be determined by deducting the volume of the seed from the volume
of seed plus sample.
4.5.3 Compression resistance. The compression resistance of Type II cellular material shall be
determined in accordance with ASTM D 945.
4.5.4 Low temperature compression set.
4.5.4.1 Low temperature compression resistance (Type II mattress inserts only). Compression
resistance at low temperature shall be determined in accordance with ASTM D 1055, after conditioning for 5 +
1/4 hours at minus 20 + 2°F.
4.5.4.2 Compression resistance at low temperature (Type II other than mattress inserts). Compression
resistance shall be determined in accordance with ASTM D 1055, after conditioning for 5 ± 1/4 hours at minus 10
± 2°F.
4.5.5 Compression set. Compression set of the cellular material shall be determined in accordance with
compression set under the constant deflection procedure of ASTM D 3574, except that the specimens shall be
compressed to 50 percent of their original height for a period of 46 + 1/4 hours at room temperature. The
thickness of the specimens shall be determined 1 minute after removal from the compression apparatus. The
compression set shall be calculated and expressed as a percentage of the original height of the sample tested.
4.5.6 Flexing. The flexing endurance of the cellular material shall be determined in accordance with
ASTM D 1055. The thickness of the specimen shall be measured 1 hour after completion of the test, and the
percent set calculated as follows:
Percent set = (a-b) x 100
a
Where:
a = original thickness before flexing.
b = thickness 1 hour after flexing.
The percent set reported shall be the average of the results obtained from the test conducted.
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