A lot work has been done in the past twenty years to raise awareness and understanding of the risks associated with combustible dusts. Between NFPA and the IFC, we have some excellent resources to design, operate and maintain areas where combustible dusts may be present. In the 2021 IFC, the “Critical Depth Layer” was re-defined/quantified…
SECTION 2203 – DUST EXPLOSION PREVENTION
2203.1 Critical depth layer
The maximum dust layer on all surfaces, including but not limited to walls, ceilings, beams, equipment, furniture, pipes, and ducts, shall not exceed the critical depth layer specified in Table 2203.1.
The critical depth layer is permitted to be adjusted for explosion hazard where further evaluated in accordance with one of the following:
1. Section 7.2.1.3 of NFPA 654.
2. Section 4.1.3.3 of NFPA 664 for wood flour.
Accumulated combustible dust shall be collected by one of the methods listed in Section 2203.5.
| TYPE OF DUST | CRITICAL DEPTH LAYER (INCHES) |
| Wood flour | 1/8 |
| All other dusts | 1/32 |