This specification covers rigid closed-cell polyurethane and polyisocyanurate thermal insulation foams for application in sandwich structural panel cores used in shelter construction for exposure to specified ambient temperatures. The unfaced foam thermal insulation boards are classified into three types (Types 1, 2, 3, and 4) according to increasing nominal density. The morphology of the insulation shall consist of a multitude of individual cells of uniform size and dimension, essentially closed off from each other, homogeneous throughout, free of voids, accumulations of unexpanded material, foreign inclusions, or seams. Upon undergoing appropriate acceptance tests, sampled specimens should adhere accordingly to the limiting values set for the following physical and mechanical properties: density; thermal conductivity; compressive strength; shear strength; percent closed cell; linear and volumetric dimensional stability; flame resistance (extinguish time and burn distance); and impact resistance.

1.1 This specification covers rigid, closed cell, polyurethane and polyisocyanurate thermal insulation for sandwich panels used in shelter construction for exposure to ambient temperatures of - 25 to 160°F (- 32 to 71°C). Painted surfaces of shelters in actual field use reach temperatures of 200°F (93°C). The materials in this specification must be capable of withstanding processing, (laminating) temperatures of 110°C (230°F).

1.2 The values stated in either inch-pound or SI units are to be regarded separately as the standard. The values given in parentheses are for information only.

1.3 The following precautionary caveat pertains only to the test method portion, Section 12, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.