Dust Collector and static electricity

[wgander]

Is there anything I can do to minimize static electricity?
Depending on the weather, there are times when the outside of the hoses and wand attract sawdust when in use. I move the Dust Collector around the shop so running wire through the hose (as in a permanent system) doesn't seem practical.

[JPG]

Unless you make the outer surface of the hoses etc. conductive, there will be that static buildup/dust attraction.

If it be doing it's job, where is the 'attracted' dust coming from?;)

[paulmcohen]

Is there anything I can do to minimize static electricity?
Depending on the weather, there are times when the outside of the hoses and wand attract sawdust when in use. I move the Dust Collector around the shop so running wire through the hose (as in a permanent system) doesn't seem practical.

Running wires inside the hose can cause clogs, It is recommended to run the wires on the outside. In an case I don't know why wires should interfere with movement but if it does you can purchase anti-static or conductive hose.

[gpmark]

Physics 101 clearly shows that moving air through a hose will cause static electricity - it's only a question of how much. In a really high volume environment it's possible to generate enough to knock you to the ground and to also start fires by discharge.

Never, ever put wire inside the hose. You're inviting a fire!

Assuming you just want to make do with the hose and system you have, then running wire along the hose is the cheapest and easiest. You can duct tape it as one solution. If you can ground it to the house ground or a ground rod so much the better. You can also ground it to the green wire on the electrical system - but check so see that it's really a good ground.

Here's another warning. Only ground the system in one spot, preferably the vacuum system itself. Why? A wire connecting two devices with a non-conductor next to it is called both a capacitor (the air is the other conductor) and a path for a ground loop. Capacitors are great for storing static electricity. Ground loops love a path to follow when something electrical fails. A chief engineer friend of mine told me about a the time they turned of a big motor generator on a ship that supplied half the power to the whole ship (half a redundant pair). Instead of stopping it just kept running! The problem was there was a short somewhere else and it traveled through the hull of the ship providing all the energy to keep the motor running. In the case of a ground loop in shop equipment your the one likely to be energized!

[wgander]

I guess I'll just put up with the annoyance on those days...
Taping a ground wire to the hose and then grounding it isn't practical since I move the Dust Collector depending on what I'm doing, sometimes use one hose, sometimes two or none, and change between wand and fittings too.

[gpmark]

It sounds like you don't have a big enough system to be a physical threat. BTW - mine definitely is, it can make me really jump if not grounded!

One option would be to mount a plug or stud with wing nut on the vacuum system. When changing hoses you could simply plug the ground in. (This is how my system is set up, but I have several wing nuts on a grounding bar.)

If this is too much work and a bother you could terminate the wire in an L bracket on the hose and mount a circular ring supported with springs and L brackets on the vacuum. That way plugging the hose in would also connect the ground wire.

[robinson46176]

http://www.google.com/search?client=ubuntu&channel=fs&q=anti-static+tinsel&oe=utf-8&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&hl=en&tab=wi&biw=1080&bih=506

We used a lot of this stuff years ago when I was working in a factory where we worked with a lot of polyethylene film (mostly making bags). Often it was just laying stretched across the moving web and attached at each end to the grounded frame of the machine. Maybe you could spiral a piece of it around the outside of the hose and to a ground.
Of course I work a little differently than many but I'm not sure I understand the concern over a little dust on the hose. If it is enough to be a problem maybe the problem is just too much dust in the air?

I'm going to start a war here but I did a "LOT" of research on grounding dust collection pipes a couple of years ago and decided that if you are not getting nailed regularly that the grounding was unnecessary. According to what I found the whole fear of a static spark causing a fire in a "home shop" dust collecting situation is very highly "overblown" (sorry for the pun)...

In order to get a better picture as you research do not ask "how" to ground a home system, ask instead if it is "necessary" to ground one with a wire, inside or out...

I like to do my own research on such matters. I do very little just because "they" said so... I also spent 20 years using a dust collection system every day capturing rubber, leather, plastic, wood dust along with flammable vapors in an environment where I was often grinding a surface down with high speed sanding wheels and frequently hitting buried nails causing a shower of sparks to be sucked into the system. Never any flash or fire... Not once...

Sometimes perceived logic and reality are not even on the same page.

Everybody has always "heard" of a case, second hand, to the point that one would expect to see long lines of caskets but actual statistics do not bear those anecdotal stories out...

Maybe what we really need is "dust collector stop technology".

.

[gpmark]

As an ex-fireman I can tell you that I've been to several fires in small wood plants, some barely larger than my own, that were caused by static electricity discharge. That's according to the fire investigation teams.

According to an OSHA report:
"Static Electricity, are you at Risk?
Static electricity is the ignition source in about 13% of all chemical fires and explosions (Source: Marc Rothschild - Rohm and Haas). Static electricity is generated whenever materials come into contact and rub against each other, particularly when the materials are in particulate form and being moved at significant speeds. Electrostatic charge will readily accumulate on plastics and other insulating materials, which may ultimately result in a spark or brush discharge capable of igniting a flammable atmosphere. In the absence of any measures to control static electricity, there is a real risk that filling or emptying an FIBC will generate enough static electricity to cause and incendiary discharge."

In a small shop with a few runs and little discharge you are probably safe. If you are getting a discharge, then the danger goes up. Note too that climate and the type of particulates you have factor into it, just as do lengths of run. Mixing pipe may be a factor.

Just because you've never heard of it doesn't mean it doesn't exist. I figure I've spent less than $50 grounding my system. I also have fire extinguishers but have never had a fire. Ditto for fire insurance.

[jimsjinx]

I am a retired firefighter. Here is a little story. One fall afternoon in Arizona, a flour mill blew up, and it was massive. The cause? A broken ground to the dust handler tubes. This plant had run millions of tons of dust through the system it was estimated, and no spark. Then, that particular day, at that particular relative humidity, and with the correct amout of dust and static, it went BOOM. Just because it hasn't happened yet, don't mean it will NEVER happen. I'd suggest grounding your hoses, period. I know there is alot of hype about dust fires and all, but why chance it? Like the guy who burns a wood stove in his quaint little woodshop for 30 odd years, and finally one day his shop burns to the ground. Nah, I'd ground the system. jimsjinx