WOODWORKING SHOP+DUST COLLECTOR= CLASS II DIV II???

[TrickleCharge]

So i have a woodworking shop that is going to also install dust collector. The hazardous/classification report states that with all the woodworking equipment, the dust collector will work to "declassify" the area along with good housekeeping. Now with NFPA 499 5.4.1 this is true to unclassify a location on the basis of a dust removal system that prevents dust clouds and lay accumilations that make surface colors indiscernible. Or you can unclassify an area on the basis where excellent housekeeping prevents the same result as the dust collection system. My question is....how do i know that the dust collection will do such if the manufacturer has no proven data or samples that can support the conlusion that the dust is greater than 420 microns (Fire Code Def. of Combustible dust is dust smaller than 420 microns) or can mitigate the dust with the equipment installed to a point that would declassify it. So basically they say "well we have a dust collection system why do we need a classifation study?" But Im wondering where is the evidence that supports this claim? Any input?

Thanks

 

[GoldDigger]

My question is....how do i know that the dust collection will do such if the manufacturer has no proven data or samples that can support the conlusion that the dust is greater than 420 microns (Fire Code Def. of Combustible dust is dust smaller than 420 microns) or can mitigate the dust with the equipment installed to a point that would declassify it. So basically they say "well we have a dust collection system why do we need a classifation study?" But Im wondering where is the evidence that supports this claim? Any input?

Thanks

If the dust collection system exhausts the "dust free" air outside (the classic inverted cone cyclone dust collector exhausting outside), there should be no dependency of the collection efficiency on the particle size. So if the system does not let visible clouds form during operation it should be OK.
The effectiveness of the system will depend entirely on how closely it couples to the tools that are creating the dust, and therefore the results should be visible.
If the dust collector recirculates the air back into the building, then the collection efficiency will vary by particle size, and whether a vortex or a filter or a combination are used, the specifications would have to come from the manufacturer. But this information will have more impact on user safety from toxic or irritating dust than on the explosive/flammable dust classification.

 

[TrickleCharge]

How do I know that the proposed dust collector "coupled" with this equipment will be enough to NOT create a hazardous space without some type of sample analysis or data to back up that statement?

 

[rbalex]

I tried to get to this when everything went “kerplop” on me yesterday.

How do I know that the proposed dust collector "coupled" with this equipment will be enough to NOT create a hazardous space without some type of sample analysis or data to back up that statement?

The truth is, unless there is a great deal of fine sanding, you’re not likely to have a Class II location in the first place (420 microns is very small particles); a flash fire is more likely than an explosion for larger particles.

Good housekeeping is still more or less the key for Group G, and a sound, running cleaning system when the process is active, sure helps. It doesn’t even need to be particularly exotic. A good shop vac is often all that’s necessary. This is not to say there is no danger, I mentioned the flash fire above.