MIL-DTL-82604A (OS)
4.5.4 Softening point stability. Determine softening point on two samples run in the same
bath at the same time in accordance with ASTM D 36 using the double ring-holding device of
ASTM D 36, except use Dow Corning Silicone Fluid DC-200 of 350 centistokes viscosity in lieu
of water for the bath fluid. The thermometer shall be a total immersion, range -10 to 250 șC,
0.5 degree divisions, 16 inches in length (Arthur H. Thomas No. 9296-L40 is satisfactory).
Employ two shouldered rings and heat the samples at a rate of 5 șC/min ± 1 șC for the last
30 degrees before the softening point is reached. (Temperature program controller, Mode1
No, 240, Mfg. Hewlett Packard; Chromalox, 2000-watt hotplate, Mfg. Edwin L. Wiegard Co., can
be used to obtain the proper heating rate.) Drill the top cover of the ring-holding device to
accommodate a small glass, motor driven stirrer with a 6-inch shaft. Heat the shouldered rings
to 232 ± 2 șC before the molten compound is poured. To facilitate release of filled rings from
the bottom plate of the mold, wipe the plate with silicone oil, leaving a thin film before pouring
the sample. After samples have solidified, place mold on a hotplate. When mold becomes hot,
but still can be handled with the bare hand, remove from the hotplate and slide rings from the
bare plate to a piece of aluminum foil. Take the average of the values to determine the
softening point.
4.5.5 Penetration. Determine the penetration values in accordance with ASTM D 5.
Preheat ointment cups before pouring samples into them.
4.5.6 Flash point. Determine the flash point in accordance with ASTM D 92.
4.5.7 Heat resistance.
4.5.7.1 Preparation of test panel. Use a solvent-cleaned, mechanically polished, plain
carbon steel panel, 6 by 4 inches, by approximately ⅛-inch thick. Preheat the panel for
5 minutes, prior to dipping in the preconditioning oven (see 4.5.2.2). Coat the panel by dipping
it into the molten compound which shall be maintained at 232 ± 2 șC. Leave the top portion of
the panel uncoated. Ensure the asphalt thickness is approximately 1/16 inch on each side of
the panel. Suspend the panel with the uncoated portion up and allow to cool to room
temperature. Trim the excess compound from the bottom edge of the panel with a sharp knife.
4.5.7.2 Method. Suspend a panel, prepared as described in 4.5.7.1, in a bath of silicone
oil, Dow Corning DC-200 (350 cs), at 172 ± 1 șC for 1 hour so that the uncoated end of the
panel is uppermost and one-half of coated portion is submerged. Remove panel and cool by
immersion in cold water. Examine the film for sag or flow. A slight surface displacement at the
silicone line is permissible.
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