Fibrous glass duct liner insulations are manufactured from glass fibers bonded with thermosetting resin. They are dimensionally stable, withstand abuse, and provide a cleanable, fire-resistant interior surface designed to minimize friction loss. This interior treatment may be in the form of a coating and/or a mat facing. Two forms are available. Both are designed to meet physical property requirements of ASTM C 1071, Standard Specification for Duct Lining Insulation (Thermal and Sound Absorbing Material):

• Type I - Flexible blankets, supplied in roll form; thicknesses of 1/2 to 2 in. (13 to 51 mm) in 1/2 in. (13 mm) increments.

• Type II - Rigid boards, supplied in sheet form; thicknesses of 1 to 2 in. (25 to 51mm) in 1/2 in. (13mm) increments.