# Static Hazard in Dust Collection



## woodnthings (Jan 24, 2009)

This is a great article by Rick Christopherson on this subject, which keeps coming up on this forum. To wire the PVC ducts...inside...outside...at all....? :thumbsup: bill
Check the other Articles on the site as well. This is a very smart guy! *Static in Dust Collectors*


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## cabinetman (Jul 5, 2007)

That's an interesting write up. I've used metallic ductwork, and heavy walled PVC. Fortunately I've never had an "explosion". There needs to be sufficient kindling (dust) for that to happen. I've also tried the ground wire inside, outside, and both. I still get a static charge on the outside.












 





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## BWSmith (Aug 24, 2010)

A cpl years ago I spent countless hrs reading reports and watching NFPA videos on dust coll. hazards.Probably in excess of 50hrs........The thing about dust or flour explosions is almost universally the same.Its a secondary explosion that causes the biggest problem.If you take a handful of dust and throw it onto an open fire you'll clearly see it explode.Its the mix of oxygen and dust particles that are so combustable.

In a large factory that deals with dust,be it wood,flour,whatever....what usually happens is there will be some sort of initial explosion.Then dust that has settled on horz. surfaces gets "jarred" and creates a cloud in the air.Its this highly explosive cloud that then causes the secondary,factory leveling explosion.

Some of these facilities were of such high cleanliness factors that you would'nt believe it happens.But cleaning efforts are almost always limited to what we can see.IOWs be EXTREMELY vigilant about cleaning horz. surfaces ON TOP of high,out of sight places.

Reading and watching the NFPA stuff really made an impression on this ole shop rat.Very best of luck,BW


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## BWSmith (Aug 24, 2010)

Another reply...I really like metal ducts.Once you get a few simple sheet metal tools and learn a few VERY interesting and fun tricks(making a wye)it really comes into focus.The metal makes a much more professional setup.Just a number here but.....I'd say sheetmetal work is 75% layout,15% tools,10% labor.

We went so far as to even paint all ducts before hanging(a very nice Beige).The custom made straps are left unpainted.Am more proud of our ducting than the collectors,cleaners ect.BW


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## burkhome (Sep 5, 2010)

woodnthings said:


> This is a great article by Rick Christopherson on this subject, which keeps coming up on this forum. To wire the PVC ducts...inside...outside...at all....? :thumbsup: bill
> Check the other Articles on the site as well. This is a very smart guy! *Static in Dust Collectors*


 Thanks for the post. As one who had pretty much decided on HVAC pipe for the installation of my system, I appreciate the additional validation.


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## rrbrown (Feb 15, 2009)

Bill thanks for the post. I have only one problem with this entire subject. There has _*never*_ been a single case of a home shop explosion involving PVC duct or otherwise. I agree with almost every other thing in the article except the use of the word *rare* since no one has ever showed a single case. 

This has been argued, discussed or what ever you want to call it, to no end. I would just like to see proof of something that is said to be rare. It seems to be a hypothesis that in theory it could happen rather then a fact that it has happened in at least one rare instance.

People win the lottery everyday it is possible it has happened. I would think that there would be some proof of at least one case where this dust explosion has happened in a home shop using PVC if it actually happened.

That said nothing is impossible and in theory maybe it could happen but I want documented facts or it's nothing but a unproven hypothesis which is bad science.


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## rrich (Jun 24, 2009)

I have to agree with Richard. What it amounts to is two things, burnable material and ignition.

In a *HOME* workshop neither is present. The dust is not in the air in sufficient quantity to support combustion. A static spark does not have sufficient energy to cause ignition. 

To support combustion, the wood dust in the air would have to be so thick that humans couldn't breathe.

AND the wood dust would need to be near the consistency of flour for combustion to be possible. 

Maybe if you hosted the "Great American Belt Sander Sand Off" finals with 50 simultaneous contestants. And then you put a propane torch into the dust stream, maybe, just maybe you might get ignition. Maybe, but I doubt it.

Remember that a dust explosion requires a four sided fire triangle.
Heat
Oxygen
Combustible material
The combustible material in sufficient concentration to support combustion.


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## burkhome (Sep 5, 2010)

BWSmith said:


> Another reply...I really like metal ducts.Once you get a few simple sheet metal tools and learn a few VERY interesting and fun tricks(making a wye)it really comes into focus.The metal makes a much more professional setup.Just a number here but.....I'd say sheetmetal work is 75% layout,15% tools,10% labor.
> 
> We went so far as to even paint all ducts before hanging(a very nice Beige).The custom made straps are left unpainted.Am more proud of our ducting than the collectors,cleaners ect.BW


 Would love to see a photo.


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