MIL-DTL-24688 Insulation, Thermal And Acoustic Absorptive, Cellular Polyimide FoamThis specification covers thermal and acoustic absorptive cellular polyimide foam insulation for use on bulkheads, overheads, and ventilation ducting. This specification also covers preformed thermal pipe insulation for use on piping operating at temperatures up to 600 degrees F in shipboard applications \(see 6.1\).

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MIL-DTL-24688A

4.4.7 Mass loss by tumbling (type I and type III). Mass loss by tumbling shall be determined in accordance

with ASTM C421 (see 3.9).

4.4.8 Corrosiveness (type I and type III). Corrosiveness of the material shall be determined in accordance with

the corrosiveness method of ASTM C665 (see 3.10).

4.4.9 Wicking (type I and type III). Wicking of the material shall be determined in accordance with

ASTM C1559, Procedure A. Only the room temperature water test shall be performed for a period of 48�2 hours

4.4.10 Puncture resistance (type II, class 1 only). Puncture resistance shall be determined in accordance with

the method specified in TAPPI T 803, except as follows: The 24 by 18-inch test specimen shall be placed with the

cloth faced down between the clamping plates. The loose sleeve shall be placed against the base of the puncture

point and the pointer shall be set about 1 inch above the expected reading. The pendulum shall be raised to the

horizontal position. The pendulum shall be released by pushing the latch handle to the left. The reading on the

proper scale shall be noted after the pendulum has completed its swing. Two determinations shall be made in the

warp direction and two in the filling direction of the cloth on each specimen (see 3.12).

4.4.11 Compressibility.

4.4.11.1 Type I, type II, and type III, classes 1, 2, 3, and 4. Compressibility of the unfaced foam only shall be

tested in accordance with ASTM D3574, Test Method C, with exception that the foam shall be tested unflexed

4.4.11.2 Type III, classes 5 and 6. Compressibility of the unfaced foam only shall be tested in accordance with

ASTM D1621 (see 3.13.3).

4.4.12 Sound absorption (type I and type II, class 2). Sound absorption coefficients shall be determined in

accordance with ASTM C423 using Type A mounting (see 3.14).

4.4.13 Thermal conductivity.

4.4.13.1 Type I and type II, class 1 only. Thermal conductivity shall be determined in accordance with

ASTM C177 or ASTM C518 (see 3.15.1). In case of a dispute, ASTM C177 shall be the referee test method.

4.4.13.2 Type III. Thermal conductivity shall be tested in accordance with ASTM C335 (see 3.15.2).

4.4.14 Upper temperature limit (type I, type II, and type III). Upper temperature limit shall be determined at

the pipe insulation's intended maximum use temperature (400 �F for Type I, Type II, and Type III, Classes 1 and 2

and 600 �F for Type III, Classes 3, 4, 5, and 6). Testing shall be performed in accordance with ASTM C411 and

ASTM C447 (see 3.16).

4.4.15 Fire resistance tests.

4.4.15.1 Type I and type II. Fire resistance tests shall be performed in accordance with 4.4.15.1.1 and

4.4.15.1.1 Flame resistance (type I and type II, classes 1, 2, and 5). Type I and Type II, Classes 1, 2, and 5

shall be tested in a room fire test in accordance with ISO 9705 (see 3.17.2.1).

4.4.15.1.2 Duct insulation room/corner test (type II, classes 3 and 4). Type II, Classes 3 and 4 shall be tested in

accordance with the ventilation duct insulation room/corner fire test (see 3.17.2.2 and Appendix B).

4.4.15.2 Flame spread and smoke (type I, type II, and type III). Flame spread and smoke developed shall be

determined in accordance with ASTM E84 (see 3.17.2.3, 3.17.2.4, 3.17.3.1, and 3.17.3.2).

4.4.15.2.1 Pipe insulation room/corner test (type III, all classes). The pipe insulation room/corner test shall be

performed in accordance with Appendix A (see 3.17.3.3).