5 Determination of Dust Explosion Hazard Areas and Flash-Fire Hazard Areas
5.1 Dust Explosion and Flash-Fire Hazard Areas.
5.1.1 Those portions of the process and facility where defla- gration venting is not currently required and a dust explosion hazard or flash-fire hazard exists shall be evaluated to deter- mine appropriate protection levels from the effects of these hazards in accordance with this section and the fire protection and building construction sections in each metal chapter, Chapters 7 through 14, and Chapter 15.
5.1.2 Dust explosion hazard areas and dust flash-fire hazard areas shall be deemed to exist in all operating areas of facilities processing or handling combustible metal dusts, unless a haz- ard analysis determines otherwise.
5.2 Segregation, Separation, or Detachment to Limit Dust Haz- ard Areas.
5.2.1 It shall be permitted to use segregation, separation, or detachment to limit the extent of a dust explosion hazard area or a dust flash-fire hazard area.
5.2.2 Use of Segregation.
5.2.2.1 Physical barriers that are erected to segregate dust flash-fire hazard areas, including seals at all penetrations of floors, walls, ceilings, or partitions shall have a 1-hour fire re- sistance rating.
5.2.2.2 Physical barriers that are erected to segregate dust explosion hazard areas shall be designed to preclude failure of those barriers during a dust explosion in accordance with NFPA 68, Standard on Explosion Protection by Deflagration Venting