Vaccuum systems

Yes and NO. I am using 4" PVC pipe overhead and do not have it grounded. Did you ever see the (Of all the things I have lost, I miss my mind the most!) - who are the two guys who test all the theories? - anyway, they did a segment on the static build up on PVC and found that it just does not build enough to give a significant discharge, if any at all. It seems PVC is really lousy at holding a charge.

Deb

"Kevin Cleary" wrote: I was wondering if anyone else has their vaccuum system connected by PVC

^^^^^^^^^^^^^^^^^ I have my vacuum hooked up with 1" flexible plastic tubing (Tygon) and it is not grounded. I don't see any need--there is not enough air flow in a vacuum line, even with minor leaks, to generate much static electricity. You really have to have dry air, vigorous motion and very good insulation to generate sparks.

I guess I need to ask, which kind? Dust collection or vacuum clamping?

Yes.

No.

I like to live dangerously. ;-)

The two guys you are thinking of are Adam Savage, And Jamie Hyneman, from the Mythbusters. While they did prove PVC has a hard time holding a significant charge, I personally like to ground my vacuum tubing. As all it takes is one small spark and the right dust condisitions to create a potential flash fire.

But thats just my two cents.

Donald Vivian

Good point, Leo... we've been at about 20% humidity for a week or so and the cats have gotten shocked enough to be afraid of us, but they haven't burst into flames yet..

I take a lot more precautions for static shock around the computers then the shop..

mac

Please remove splinters before emailing

There is a difference. While the PCV in a pipe can build little charge, this is NOT true for the dust moving through the pipe. That's where the real danger is. The pro's recommend a bare wire through the pipe for that reason

So its best to wrap grounding wire around the PVC and then attach it to a groounding rod?

Kevin

Grounding insulators is a tough task. PVC is a pretty good insulator. Not to mention that wrapping the outside will do even less for the inside than the out.

The "pro's" (sic) still haven't produced a single instance of dust explosion in a sanding dust pipe, and the science says the density, particle size and heat of the spark which would jump from the pipe to the interior ground (?) are not likely to hit a perfect combination, even if they were the proper charges

no, no, no, no.

if you are going to do this at all, you need the wire inside the pipe - I'd use steel instrument wire because it will resist the dust abrasion, and I'd drill a little tiny hole in the pipe occasionally to "sew" the wire through so it stays on the side of the pipe. or, there is conductive pipe available - frequently the black pipe is conductive enough to prevent static build up, but you would want to check this via the specifications.

You can attach the wire to any ground, a rod, the conduit in which you electrical power runs, a water pipe, etc.

Asking isn't the same as thinking, but it's a fair substitute and easier for me, so: ********************************************

How abrasive is the dust from a woodturning shop at the dust removal velocities encountered in a turning shop? Does it abrade PVC walls?

Between the fixed PVC and the moving dust are electrons stripped off some or all of the dust particles or they stripped off the PVC? IOW, is the charge (voltage) between dust and PVC tubing or between dust particles?

Does living in areas of high humidity remove/lessen the possibility of explosion from shop dust? Is there a correlation between relative humidity and charging of dust moving in turning shop dust removal situations'? Is the threshold RH known?

What is the ground wire inside the PVC pipe supposed to prevent; ie. does the dust burn like gasoline vapor in a car's engine or does it explode, whatever the difference is.

Would a humidifier reduce the risk of explosion in dry climes or would it just make the turner uncomfortable and rust all his tools?

I know there are supposed to be no foolish questions, but asking without thinking produced the above. Sorry. :)

Turn to Safety, Arch Fortiter

Try reviewing the info on this site.

Hi jev, I appreciate your response, but I'm unsure of your intent. I thought these were legitimate questions and I don't like to assume knowledge which I have not. Did the site you suggested not get posted or did you refer to mine in some way ?

If you were not pleased, I regret the misunderstanding, but I still would appreciate answers from someone who knows. I could look it up, but better to get a friendly reply from a woodturner's slant.

Thanks in advance for your explanation.

Regards, Arch

Sorry forgot to post the link - my apologies

Wow! What a great link. Many thanks, jev.

Turn to Safety, Arch Fortiter