How much do you know about protecting your factory against the risks of a combustible dust explosion? Take this brief quiz provided by Camfil Air Pollution Control ( and test your personal knowledge.

1. A dust is considered to be combustible if the Kst value (defined as the speed of pressure rise) is:

a)      >0 Kst

b)      >100 Kst

c)       >150 Kst

d)      >300 Kst

2. The organization tasked with developing and updating standards for explosion prevention and combustible dust safety is:

a)      OSHA

b)      NFPA

c)       U.S. Chemical Safety Board

d)      None of the above

3. Because they use water to capture dust particles, thereby removing fire and explosion hazards, wet scrubbers are always the collection technology of choice for capturing combustible dusts.

a)      True

b)      False

4. Of the following explosion protection devices, the one that is likely to be the least costly is:

a)      Chemical isolation

b)      Chemical suppression

c)       Explosion venting

d)      High-speed abort gate

5. A heavy-duty dry dust collector, constructed of thick gauge metal and with a high pressure rating, will stand up better in the event of a combustible dust explosion and may enable you to use a simpler and less costly explosion protection system to comply with NFPA standards.

a)      True

b)      False

6. Dust explosions in processing facilities can be caused by:

a)      Poor housekeeping practices

b)      Dust backup in the dust collector’s hopper

c)       Dust entrained on horizontally mounted filters

d)      Static electricity discharge

e)      All of the above


1. a) >0 Kst. Unless a dust is completely inert (0 kst), it has the ability to explode and must be treated as a potential hazard.

2. b) NFPA. The NFPA develops and updates standards on fire and explosion protection, while OSHA is charged with enforcing those standards in the workplace.

3. b) False. It is true that wet scrubbers can often eliminate the need for costly ancillary explosion protection devices. However, dry media cartridge dust collectors offer a number of advantages such as higher efficiency removal of fine dusts, large airflow capacities, and more efficient operation. A hazard analysis can determine the best collection technology for your specific combustible dust application.

4. c) Explosion venting. An explosion vent is a relatively simple “passive” device that minimizes damage to a dust collector in the event of an explosion. The other devices are all “active” systems that are actually designed to prevent explosions from occurring. Active systems involve much costlier technology.

5. a) True. When a collector is equipped with an explosion venting or suppression system, as required when handling combustible dusts, vessel strength is an important factor in sizing and selecting explosion protection equipment. Often, a heavy-duty collector can even withstand an explosion and continue in service afterwards.

6. e) All of the above. TheNFPA and other organizations have identified numerous conditions that can lead to dust explosions, and these are just a few of the culprits.

Rating Your Score

5-6: Excellent. Congratulations on staying up to date on the important topic of combustible dust control.

3-4: OK to good. You’re familiar with some of the fundamentals of combustible dust hazards but could use further guidance.

1-2:  Poor to fair. Better brush up on your NFPA combustible dust standards!