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Forum topic by BJODay posted 09-25-2013 06:01 PM 1210 views 0 times favorited 15 replies Add to Favorites Watch
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BJODay

512 posts in 1403 days


09-25-2013 06:01 PM

Topic tags/keywords: static dust collection

I was using my planer for the first big project. I have it connected to my DC via 4” plastic hose. I noticed the hair on my arms standing up anytime I got near the DC hose. Is this common? I know static is generated with any type of movement.

Later I took a length of wire and ran it from the hose clamp on the DC hose to my cold water pipe. This seemed to lessen the static but I also wasn’t planing the same volume as when I first noticed the static.

BJ


15 replies so far

View brtech's profile

brtech

893 posts in 2382 days


#1 posted 09-25-2013 06:07 PM

It’s a known issue. The airflow in the plastic hose builds up a static charge.

There have been persistent rumors that this is an actual safety problem, with a possibility of an explosion in the DC. This has been debunked – there is no safety risk.

It still could give you a zap.

There aren’t a lot of good grounding ideas. A wire inside the hose won’t work. Some folks have wrapped a spiral wire around the outside and reported that it helped, but I’m dubious.

View Charlie's profile

Charlie

1100 posts in 1746 days


#2 posted 09-25-2013 06:11 PM

There’s a spiral wire IN the plastic hose! :)

View jonah's profile

jonah

687 posts in 2758 days


#3 posted 09-25-2013 06:18 PM

It’s not going to explode. It may or may not shock you a little. Ground it if there is an easy way to do that, otherwise just live with it.

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brtech

893 posts in 2382 days


#4 posted 09-25-2013 06:20 PM

It’s usually embedded in channels, right, not actually exposed. You can try grounding it, but I suspect you won’t get much benefit.

View crank49's profile

crank49

3980 posts in 2431 days


#5 posted 09-25-2013 06:46 PM

I have responded to similar posts to this before. In fact, on several occasions.

I used to work at a foundry. We had millions of dollars worth of dust collecting equipment.
I bought and installed most of it. Designed some of it as well.

We had one dust collector blow up during my 30 year career.
It was a small 5,000 CFM collector on the wood pattern shop.

The Stanley hammer handle factory was just about a mile from our plant.
They had explosions and fires about every couple of months until they installed a CO2 automatic suppression system on their dust collection system.

Here is a link to a publication that is widely read in the dust control business.
http://www.baghouse.com/2011/01/19/the-potential-for-dust-explosions-in-dust-collection-systems/

To say this is a “rumor” and worse, one that has been “debunked”, is a pretty ignorant thing to say.
Dust explosions are not common, but they sure as hell are not rumors.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View Richforever's profile

Richforever

751 posts in 3180 days


#6 posted 09-25-2013 07:10 PM

Haven’t done it, but I’ve heard that the metal dust collection tubing prevents the static if it is grounded properly.

-- Rich, Seattle, WA

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Grandpa

3256 posts in 2135 days


#7 posted 09-25-2013 07:41 PM

Crank, I did read that there are industrial explosions but there had never been a residential hobby shop dust explosions. I am not sure how the machine can tell the difference but I guess it is because the home owner/hobby person uses the collector far less than an industrial plant.

I believe that bonding your machines is the correct terminology. This is done with a wire from one to the next and it is easiest when attaching to the collection pipe. Can’t ground an insulator can you?? You can get the same charge when walking under a high voltage power line. I know a guy that got shocked from this.

View BJODay's profile

BJODay

512 posts in 1403 days


#8 posted 09-25-2013 07:56 PM

Crank 49, that is an informative article. Thanks for the info. I’m familiar with the mechanics of dust explosions. I wasn’t too concerned about that happening in my workshop. I am more concerned about having something smolder unnoticed after a leave the shop. The next time I planing I’ll set up a bonding wire in a more permanent location. Then I’ll be able to monitor its effectiveness a little better.

Thanks for the responses,
BJ

View Steve Peterson's profile

Steve Peterson

324 posts in 2542 days


#9 posted 09-25-2013 08:23 PM

I used to get a spark from the wire inside some flex duct on my bandsaw. The end of the wire was sticking out and the gap was just the right size. I simply bent it a bit further so it touched the metal frame and the problem went away.

I can occasionally feel a small buildup of static on the PVC pipe, but do nothing about it. Most of it is mounted at the ceiling, so it is out of the way. I rarely get close enough to notice the static.

-- Steve

View Bill White's profile

Bill White

4448 posts in 3420 days


#10 posted 09-25-2013 09:40 PM

OK! Here’s the easy and cheap/inexpensive solution.
Get some dryer cloths..the anti-static ones, suck ‘em thru the DC hose(s). Let ‘em live in the DC. No more static.
I even rub the exterior of my Ridgid vac every so often just to help.
Bill

-- bill@magraphics.us

View bigblockyeti's profile

bigblockyeti

3665 posts in 1180 days


#11 posted 09-25-2013 10:14 PM

I worked in a shop where they had some European 10hp dust collector and ran 10” green thin wall sewer PVC for the dust collection, ripping a lot of dry wood would produce a tremendous static buildup that could zap you from over 6” away in the right conditions. As the safety manager, it was my responsibility to remedy this. The solution was running a thin braided copper wire from the metal on each machine through the duct work back to the dust collector. Feeding it through was easy as the wire was fairly flexible, I just tied a rag to the end of it and feed it from the disconnected end off each tool while the collector was running. It fixed the problem completely.

View Shawn Masterson's profile

Shawn Masterson

1297 posts in 1408 days


#12 posted 09-25-2013 10:54 PM

On a 10” line you can run a wire inside the pipe. On a 6” I am concerned about blockages. The INDUSTRIAL DUST EXPLOSIONS are using DC blowers that move monstrous amounts of air. I have never read or seen anything documenting an explosion in a small DC(under 5000 cfm).

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jonah

687 posts in 2758 days


#13 posted 09-26-2013 12:56 PM

I love how he described an explosion involving a “small” dust collector that moves 5,000 CFM. That is roughly three or four times the size of the average hobbyist setup.

View crank49's profile

crank49

3980 posts in 2431 days


#14 posted 09-26-2013 01:38 PM

Well, 5,000 CFM was small for that site. My smallest collector was 1,200 CFM, in the metallurgical lab.

At the other extreme I had a unit around back that was rated at 215,000 CFM and was connected to the plant with an 8 foot diameter duct, 400ft long.

It’s all relative, the physics don’t change. It takes the same horsepower to suck a cubic foot of air through a pipe and pull it through a filter at a specific pressure, regardless of the size.

I just observed that the one explosion I had, and the ones I knew about at the Stanley handle mill, all had one underlying common factor. They all were dealing with wood dust.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View Bluepine38's profile

Bluepine38

3341 posts in 2545 days


#15 posted 09-26-2013 03:07 PM

Sawdust can explode and burn, but most small shops do not produce enough dust to cause that problem,
and most of the bigger shops I have seen tend to have metal duct work, which grounds everything. An
explosion could happen, so all my plastic hoses have their wire spirals gounded to the metal ductwork and
the dust collector is also grounded. I am old enough that I do not like to take chances.

-- As ever, Gus-the 77 yr young apprentice carpenter

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