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 deflagration 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 flashfire hazard areas shall be deemed to exist in all operating areas of facilities processing or handling combustible metal dusts, unless a hazard 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 resistance 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