scope:

This specification covers the general requirements, property and performance requirements, quality, and inspection tests. An approved source list is included.

When no Grade is specified on the print, Grade 1 material will be provided.

If insulating performance is affected by orientation, the attachment side must be identified.

APPLICATION

This specification applies to under hood acoustical insulation requiring high sound absorptive characteristics. The NAVISTAR Vehicle Acoustics Group must approve material supplied for acoustical applications. Various grades are specified for Type I, Type II, Type III, and Type IV requirements for certain thermal environments or operating conditions.

Grade 1 - Material is a composite blend of synthetic and natural fibers, recommended when under hood temperatures are above 275˚F.

Grade 2 - Material is made from polyester fiber and is recommended when under hood temperatures are below 275˚F.

Grade 3 - Material is made from polyether urethane acoustic foam, which may be composited with facing materials. It is recommended when under hood temperatures are below 225˚F. Specially designed Grade 3 foam composites with facings may be used for under hood temperatures above 275˚F as long as the composite does not come into direct contact with the heat source.

Grade 4 - Material is made from a combination of polypropylene micro fibers and polyester staple fibers. It is designed for use in environments where the operating temperature is less than 250˚F.