Classified Locations - paper dust

[patrick7]

I'm trying to find out if areas containing paper dust (from tissue-grade papermaking operations) are considered hazardous locations. Looking at the NEC, NFPA 499 and NFPA 664, it appears cellulose is a Group G combustible dust. But it also looks like this pertains more to the fine wood dust that is produced in some wood processing and wood working facilities, not to paper dust. On the other hand, these standards also indicate that their lists are not all inclusive, and I can't find anything that specifically excludes paper dust. Any advice or guidance would be sincerely appreciated!

 

[rbalex]

Re: Classified Locations - paper dust

It?s important to determine whether you have a combustible dust in the first place. See NFPA 499 Section 1-3 definition:

Combustible Dust. Any finely divided solid material 420 microns or less in diameter (i.e., material passing through a U.S. No. 40 Standard Sieve) that presents a fire or explosion hazard when dispersed.

More likely this is a Class III application:

500.5(D) Class III Locations. Class III locations are those that are hazardous because of the presence of easily ignitable fibers or flyings, but in which such fibers or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitible mixtures. Class III locations shall include those specified in 500.5(D)(1) and (D)(2). [ Bold Italics added]

Look through the definitions and Article 503 and evaluate your actual materials carefully. Let us know if you need more assistance. More than likely, with good housekeeping, you would have very little to classify. Also note that there is virtually no difference between Division 1 and Division 2 for Class III installations.

Edit: completed the Section reference in 500.5(D) citation.

[ May 19, 2005, 01:48 PM: Message edited by: rbalex ]