MIL-PRF-2818D
4.5 Test methods.
4.5.1 Non-fibrous material (shot content). The non-fibrous material (shot) content shall be tested as
specified in ASTM C 892, Annex 2.
4.5.2 Alkalinity. The alkalinity test shall be performed as follows: Weigh a 5 + 0.01 gram representative
sample of the insulation material, and introduce into a 500 milliliter (mL) Pyrex Erlenmeyer flask. Wet with 5 mL
of 95 percent ethyl alcohol and add 400 mL of distilled water. Reflux for 4 hours plus or minus 5 minutes. At the
end of this period, disconnect the condenser and filter at once through a no. 41 Whatman paper, or its equivalent,
supported in a Buechner funnel and connected to a suction source. Wash the flask and residual material three
times with 25 mL portions of hot distilled water. Titrate the combined filtrate and wash solution immediately with
0.02N H2SO4 using 6 to 8 drops of a 1 percent solution of phenol red indicator to the disappearance of the pink
color. Run a blank determination on the same amount of distilled water and alcohol and substitute the titration
value in the formula below:
Percentage alkalinity as Na2O = (A-B)N x 0.031 x 100
W
Where:
A - mL H2SO4 required to titrate total sample
B - mL H2SO4 required to titrate blank
N - Normality of the H2SO4
W - Weight of the samples in grams
A representative sample may be prepared by taking borings with a large cork borer through the cross selection of
the insulation.
4.5.3 Corrosiveness to steel, copper, and aluminum. The insulation shall be tested in accordance with the
corrosiveness method of ASTM C 665.
4.5.4 Binder content. The binder content of each sample tested shall be determined by heating not less
than 1/2 square foot of insulation material separated into small pieces to approximately 800 degrees Fahrenheit
(F°) for 3 hours in an oven vented in such a manner as to ensure complete circulation of the atmosphere of the
entire oven chamber, preferably by fan or other forced circulation methods. The weight before and after heating
shall be taken under atmospheric conditions of the same relative humidity.
4.5.5 Dimensions and density. The dimensions and density of the insulation shall be determined in
accordance with the method specified in ASTM C 167.
4.5.6 Thermal conductivity. Thermal conductivity shall be determined in accordance with the method
specified in ASTM C 177.
4.5.7 Moisture absorption. A 3-1/2 by 3-1/2 by 3 inch specimen of the insulation material component
shall be weighed and then subjected to an atmosphere of 90 + 3 percent humidity at 120 + 3°F for 6 hours. The
specimen shall be weighted immediately upon removal from the test chamber and the percent moisture absorbed
shall be determined.
4.5.8 Resistance to vibration. Vibration resistance shall be conducted in accordance with the test method
in the Supplementary Requirements Section of ASTM C 592.
4.5.9 Fire resistance. Fire resistance shall be conducted in accordance with the test method in MIL-STD-
1623.
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