The FM approval or the FM 4924 standard is an approval requirement for insulation material used on the exterior of non-combustible pipes or ducts. This standard uses a full-scale pipe chase test for tube insulation and a full-scale room test for duct insulation (sheets). Tests in this standard are different from the BS 476 standard where small samples are exposed to heat or flame.

How are pipes tested?

The setup:A three-sided ‘L-shaped’ channel consisting of a horizontal segment attached to a vertical segment contains three insulated pipes which are laterally spaced inside the channel.

The procedure: A propane burner is placed at the end of vertical pipes and the samples are subjected to an exposed fire for 10 minutes (Figure 3).

The result: In order to pass this standard, the following requirements must be met:

1. the fire shall not propagate to the end of the horizontal segment
2. the temperature must not exceed 300°C, and
3. the insulation falling off the horizontal segment must be extinguished within 10 seconds of hitting the base of the channel.

How are sheets tested?

The setup: 8ft by 8ft test samples are mounted on the back wall and adjacent left wall of a room. A fire pan, starter material and wood crib is placed in the corner between these two walls.

The procedure: The starter material is ignited in the room and the test runs for 15 minutes.

The result: In order to pass this standard, the following requirements must be met:

1. Charring of the foam plastic panel cores do not extend to the outer extremities of the test area within 15 minutes.
2. Smoke levels generated during the test are not excessive.

What does this mean for my project?

FM approved products are known for their quality, technical integrity and performance in tough conditions. Having the FM approved mark assures you that the product of choice will uphold the safety standards of your project.