Question for PVC duct users

[Paul Greathouse]

I use several small tools in the same general area of my shop and have been connecting and disconnecting them from my shop vac when used. I want to setup a PVC header with shutoff valves, to connect each one of them into, so that I don't have to do the connecting and disconnecting.

Sort of a mini dust collection duct system. I have done some experimenting with hoses and it appears that I have plenty of suction even when using small, long hoses, so the problem won't be length from the vac.

My question is with grounding for static charge.

Will I need grounding with this type of setup? My maximum header length will be about 20'?

Do I run the ground wire inside the pipe and then exit the pipe at some point and go to ground or can the wire be attached to the outside of the pipe?

I haven't had any problems with static using the hoses but after seeing some of the threads about grounding PVC on the larger systems, I wanted to ask.

Also, I haven't seen any thread about using a small duct system like this. I would appreciate any other general information from someone that has done something similar to this. Advantages/Disadvantages, Tips, Pictures would be great.
The header will have the following tools attached to it:
Compound miter saw, circular saw, RO sanders, routers, or anything else small that has a dust port connnected to it.

I don't really like the boom idea, because I see where it could get in the way at times. I would rather have my hoses drop down to the center of the table and still be able to get around all four sides of the table without having to work around the boom.

[glenn bradley]

You may get a lot of replies on this but I side with the study done where they were actually able to finally get wood dust to combust in a laboratory. However, the environment required does not exist much in the real world and if the environment approached that which is required you would have left the shop a long time ago so you could breathe.

That's just the side of the fence I've chosen to sit on. Read more here and many other places on the web:

http://mywebpages.comcast.net/rodec/woodworking/articles/DC_myths.html

[Jim Becker]

No "Grounding" is necessary...you can provide a "drain" if you prefer for personal comfort, but otherwise, I wouldn't bother.

There actually have been several commercial "small diameter duct" solutions available for shop vac use from the likes of Sears and Home Depot. Doing this in a small way for convenience at the bench shouldn't pose a problem, but I wouldn't install it the way that those firms have pictured with duct all over a shop. And do use small blast gates to isoloate to the tool being used.

[Randal Stevenson]

Been on both Mythbusters and government studies. Things like Grain elevators, and commercial shops produce enough dust, in the right combination of air/particles to go boom. Shop vacs have been sucking up wood dust/drywall dust, etc for years without issues, and shop vac even sells a dust collector kit, to turn their vac into a small collector. No grounding.

That said, and for personal comfort, You can have a ground run on the outside, with the screws penetrating the plastic, so any miniture voltage, would transfer outside to the wire. Anything (wire/screws) on the inside of the pipe, will cause you to have more clogs, and you run a higher risk of having a fire, if you hit something metal and suck up a burning ember, then you do going boom.

[Dewayne Reding]

Been on both Mythbusters and government studies. Things like Grain elevators, and commercial shops produce enough dust, in the right combination of air/particles to go boom. Shop vacs have been sucking up wood dust/drywall dust, etc for years without issues, .........................

Thats the key point I think. Somebody's vacuum cleaner would have blown by now. However I don't need a government study to believe grain dust can explode. All I have to do is drive by the vacant lot that used to be our local Robin Hood Flour Mill. It was leveled by a dust explosion when I was a boy.

[Jim Young]

No explosions at my house yet from the DC system. I didn't ground my pipes.

[Mike Seals]

Explosions are less likely than a fire. The static will build up in any transfer system and if it builds strong enough, could cause a spark that can ignite a source of fuel, dust being a good one.

I've worked many industrial transfer systems and grounding was a must. You'll always find those that say it's not necessary, but I look at it from the stand point of my seat belt, I wear it anytime the car is moving, I've never been in a wreck, should I quit wearing it?

[Jim Becker]

Explosions are less likely than a fire. The static will build up in any transfer system and if it builds strong enough, could cause a spark that can ignite a source of fuel, dust being a good one.

I've worked many industrial transfer systems and grounding was a must. You'll always find those that say it's not necessary, but I look at it from the stand point of my seat belt, I wear it anytime the car is moving, I've never been in a wreck, should I quit wearing it?

From all evidence...this is a non-industrial situation and there has never been an "explosion" from wood dust in this kind of setting. Rod Cole's article referenced above is pretty clear on that point.

[Dan Gill]

but I look at it from the stand point of my seat belt, I wear it anytime the car is moving, I've never been in a wreck, should I quit wearing it?

Because many, many other people have been in wrecks. There is ample evidence that wrecks happen. It just hasn't happened to you . . . yet. There is no evidence for home shops burning or exploding from ungrounded PVC collection systems.

The two cases are not parallel.That is not the case with ungrounded home shop PVC dust collection systems.

[Mike Wilkins]

Fine Woodworking magazine published an article in one of their annual Shops and Tools issues on this very subject. Using PVC in a home shop environment is highly unkikely to cause enough static to cause an explosion. The amount of material that a home shop dust collection system can move is not like being in an industrial woodworking shop setting.
But the major point in the article is that PVC is a natural insulator. So there should not be any problems. But for peace of mind, lots of folks will add some anti-static wiring to their system.
I have been using PVC for several years; purchased some wire just for this purpose, but the package is still unopened. So far so good.
Now lets go make some sawdust.

[Jim Becker]

Mike, the FWW article was written by Rod Cole who's own site was referenced earlier in this thread.

[Rob Bodenschatz]

Mike, do you get any shocks by not installing the grounding wire? I have decided that I'm not worried about the fire risk. I have heard that the static charges these things can give off can be very, well, shocking when touched, though. More than just the socks-on-the-carpet variety.

[Mike Seals]

Because many, many other people have been in wrecks. There is ample evidence that wrecks happen. It just hasn't happened to you . . . yet. There is no evidence for home shops burning or exploding from ungrounded PVC collection systems.

The two cases are not parallel.That is not the case with ungrounded home shop PVC dust collection systems.

Has there ever been any ESD that have caused an explosion or fire?

For what it cost's to keep the ESD to a minimal range, I'll add the drain wire. When I first put my system in, it was the dead of winter. I cranked it up and you could feel the static charges on the pipe, arm hair would raise when near the pipe. I decided it was better to be safe than sorry, you never know what could happen and it's one less hazard to deal with.

I work in the petro-chemical industries, I'm sure safety has been pounded in my head so well that I over do some things. If I see a potential hazard, I correct it before I can become one of those rare instances, proof or no proof.

[Paul Greathouse]

Thanks for the replies, I feel better about going ahead with the PVC now. I may go ahead and attach a ground wire to the outside, that wouldn't be much of a problem.

Interestingly, I did notice the hair standing up on my arm when I grabbed a joint of PVC pipe off the rack at the Big Blue Box store this afternoon. Seems like its done that before, I guess PVC always carries a little static charge.

[Jim O'Dell]

I can feel the static on the back of my arm when I'm close to the PVC and my Clear Vue is running. I keep touching the pipe to see if it zaps me. Haven't gotten anything at all so far, and lately I've been cutting OSB, and MDF that has a layer of plastic laminate on it. Jim.

[Matt Meiser]

The only thing I've ever gotten zapped by was the cheap flex hose I used between my former drum sander and the dust pipe. That was kind of painful and I did consider grounding the wire in the hose to the machine frame but I never got around to it.

What you are describing building sounds a lot like a whole-house vacuum system. I believe those are made from PVC pipe?

[Doug Shepard]

I'm kind of glad this thread came up. I would have probably been asking the same question in a few weeks. One other comment I picked up somewhere but haven't seen mentioned much: Has anyone noticed a tendency for a fine coat of dust to stick to the PVC due to static? I'm assuming this is akin to static cling in the clothesdryer. I'm not sure how you'd be able to tell if this was an issue inside the PVC. And I would think whoever posted the comment (forget where I saw it) is just referring to ambient shop dust sticking to the PVC and not leaks out of the PVC itself.

I'm sorting of getting the impression from all this is that this is one of those things that certainly cant hurt (other than your pocketbook) but that isnt really needed.

[John Durscher]

I'm running PVC pipe for my dust collector. I ran some of that aluminum duct tape (real duct tape - not the gray fabric stuff we use to fix everything) around the outside of the pipes - now it looks kind of like a barber pole. I also ran a strip down the center of the inside of the pipes. Kind of overkill, but there is absolutely no static buildup on the pipes. It really keeps the outside of the pipes from attracting sawdust like my old shopvac used to.

I did this before I discovered that it really wasn't necessary for safety purposes. However it does keep the static down - no more little shocks when you bump against the pipes.

John

[glenn bradley]

Hi, I'm not Mike but . . . I do notice the dust clinging to the shop vac hose. Much less on the DC hose. I wear rubber soled shoes (if that makes a difference) and have never been shocked. I do however get shocked when I step into the house and brush against the light switch cover screws(?).

[Keith Outten]

We recently installed a dust collection system at CNU in our new sign shop. Our in house electricians insisted on running a ground wire around the outside of the DC pipe because the owners manual required the gound wire and our installation is in a commercial shop.

I have never been a fan of running a ground wire but I will now admit that it does have merit. If you operate equipment that is sensitive to static like a Laser Engraver or a CNC Router a ground wire is a necessity. There are lots of cases where people have had equipment problems that have been attributed to static. I experienced a problem with my CNC router stopping half way through a job last year and I now believe that static was the reason for the problem. During certain seasons when humidity levels increase and drop static electricity can reach levels that are hazardous to sensitive equipment.

I still believe that dust collection systems are not a fire hazard or an increased risk of explosion in home shops. I have revised my opinon in the case of static generated being a risk to electrical equipment, particularly computer operated machines or tools that contain circuit boards.

.

[Larry Kunkler]

FOR ALL THE DC INFO IIN THE KNOWN WORLD SEE:

http://billpentz.com//woodworking/cyclone/index.cfm

GUD LUK....KUNK

[Bill Pentz]

I use several small tools in the same general area of my shop and have been connecting and disconnecting them from my shop vac when used. I want to setup a PVC header with shutoff valves, to connect each one of them into, so that I don't have to do the connecting and disconnecting.

Sort of a mini dust collection duct system. I have done some experimenting with hoses and it appears that I have plenty of suction even when using small, long hoses, so the problem won't be length from the vac.

My question is with grounding for static charge.

Will I need grounding with this type of setup? My maximum header length will be about 20'?

Do I run the ground wire inside the pipe and then exit the pipe at some point and go to ground or can the wire be attached to the outside of the pipe?

I haven't had any problems with static using the hoses but after seeing some of the threads about grounding PVC on the larger systems, I wanted to ask.

Also, I haven't seen any thread about using a small duct system like this. I would appreciate any other general information from someone that has done something similar to this. Advantages/Disadvantages, Tips, Pictures would be great.
The header will have the following tools attached to it:
Compound miter saw, circular saw, RO sanders, routers, or anything else small that has a dust port connnected to it.

I don't really like the boom idea, because I see where it could get in the way at times. I would rather have my hoses drop down to the center of the table and still be able to get around all four sides of the table without having to work around the boom.

Paul,

I seriously doubt that you will have any problems with a PVC system for a vacuum.

Likewise, I think Dr. Rod Cole has done a pretty good job dispelling the problems with PVC ducting touching off static explosions.

Unfortunately, we do have a situation with hobbyist and small shop dust collection systems where we can potentially build a mixture of air and dust that can become explosive. The issue is with these junk ducting designs that use oversized mains and too small of down drops. The rule of thumb is more than 2" difference in diameter and you will get plugging unless you open extra gates. The smal down drops limit the airflow. That limited airflow can be too low to keep from building up huge piles in our mains. These piles pose a serious fire danger. When we restore airflow, we suddenly get these piles breaking loose creating a huge blast of fine dust that could potentially become explosive. As these piles slam around they also can quickly ruin filters, motor bearings, and even the light aluminum impellers that some vendors use.

bill