183.516—Cellular plastic used to encase fuel tanks.
(1)
Not change volume by more than five percent or dissolve after being immersed in any of the following liquids for 24 hours at 29 °C:
(2)
Not absorb more than 0.12 pound of water per square foot of cut surface, measure under Military Specification MIL P-21929B.
(b)
Non-polyurethane cellular plastic used to encase metallic fuel tanks must have a compressive strength of at least 60 pounds per square inch at ten percent deflection measured under ASTM D 1621 (incorporated by reference, see § 183.5 ), “Compressive Strength of Rigid Cellular Plastics”.
(c)
Polyurethane cellular plastic used to encase metallic fuel tanks must have a density of at least 2.0 pounds per cubic foot, measured under ASTM D 1622 (incorporated by reference, see § 183.5 ), “Apparent Density of Rigid Cellular Plastics.”