Dust collectin and plastic pipe

You can pick up an anti-static/grounding system at any woodworking shop or on-line. It works like a lightning rod in a home by discharging any build-up. I don’t have one installed in my system and every once in a while I get a good annoying zap. I don’t work with any fumes or flammables so have not put it high on my priority list. The grounding system might be a good alternative to investing in ductwork.

-- Behind the Bark is a lot of Heartwood----Charles, Centennial, CO

After reading and participating in ANY discussions on this subject I have an opinion.
You may have as much caution as you will in regard to opinions.
You may also know some of the things they say about opinions.
Anyway, here goes.
There isn’t much liklihood that there would be enough charge built up in a home shop based DC to create a spark.
If such a thing did occur (very unlikely, I repeat) there is a similarly low liklihood of ignition of dust.

The causes of ignition in small and medium sized DCs can be blamed, for the most part, on ferrous metal drawn into the system, striking the impeller wheel and thus staring a small fire. Tools can also start fires by striking a nail or screw and then the sparks get sucked into the DC piping. But the chance of having those sparks stay hot enough to start fires is very low, too. Think about it. These little sparks MIGHT ignite nearby wood dust IF there is not a lot of moving air in the area, but a DC pulls a lot of airthrought the area and the tiny sparks cool quickly.
Careless smoking has also been the source of ignition in DC systems, especially in schools where the student may be sneaking a smoke in a bag house.
I have yet to hear of a properly documented case of static electricity generated in a home shop DC starting a fire or explosion. Dust explosions CAN happen in very large scale environments like grain elevators, but even they are rare.

That’s all!

d

-- If a man says something in the forest and there's no woman to hear it, is he still wrong?

I have 4” PVC plastic run throughout my 20×24 shop. I’ve never had a spark or any hint of a static shock. I would highly recommend using PVC. And my shop is in the basement so if I get a fire, my whole house burns down. I’m not worried at all. It’s cheap and easy to work with. Go for it.

-- Tony, Ohio

Food for thought

-- - Please help keep Lumberjocks an enjoyable escape by refusing to participate in political discussions. Simply spit out the bait and ignore the thread...

My stepfather used to work in a furniture factory (Broyhill), he was laid off since they moved a majority of their operations overseas. But I do recall the Sawdust building blowing up once. This building is basically 250’ long by 50’ wide, one end is open for trucks or front end loaders. The saw dust is dumped in by giant piping feeding into the roof and dumping on the floor. Lucky nobody was in the building when it happened.

-- San Diego, CA US Navy

I have metal pipes but only because i couldn’t find 6” schedule 20 S$D in my area, I think the latest thoughts are that PVC is safe and the fire danger is fairly small. I have also read the anti-static system are fairly ineffective but couldn’t hurt.

The following web site may help

http://home.comcast.net/~rodec/woodworking/articles/DC_myths.html

I have 6” pvc in my system, and I used to get shocked from the static charge all the time if I was close to the flex pipe running from the machine to the pvc pipe. To remedy it, I just wrapped a piece of stripped copper electrical wire around the last foot of flex pipe, and hang it on a piece of metal on the machine I am using. Problem solved.

-- Julian, Park Forest, IL

MIT did a study on the explosion factor of PVC with dust collection and their study showed that the chance of an explosion happening was pretty much nil. But the chance of getting a static shock on ungrounded pipe is high, but just uncomfortable for the recipient not enough to cause an explosion. There is a much bigger danger in picking up a screw or something causing a spark ,or causing it to get hot, while passing through the DC impeller. This can eventually start a fire in your dust bin or bag.

Good Luck.

-- -JimmyC...Clayton,NC- "Just smile and wave boys, smile and wave"

A 1 1/2 hp portable DC is probably a little on the light side for a overhead layout. You will want to keep ducting to a minimum, use large radius elbows, and kept them to a minimum number of also. Mounting the blower on the wall close to the cieling will shorten the main branch and eliminate elbows. Or you could buy a 2 hp Cyclone which are built more for overhead layouts.

I have a 6” PVC installation. It works great. I used screws and friction fit on most connections.

I have had NO problems with static.

This keeps coming up. In all the discussions I have read NO ONE has ever had a problem with any kind of explosions. I once read a post from a fireman who had never heard of a problem with home shop pvc static causing a fire.

All of the manufacturers are covering themselves legally with statements and warning in their warranty documents.

So…. I think PVC is great. Easy to work with and a great solution.

Here is my install LINK#

I used to use pvc for my dust collector, but have recently switched to metal.

Here’s a good article on about grounding, in WOOD Magazine.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

I also use PVC (ASTM 2729) with no problems. There hasn’t been one case where PVC has caused any explosions, it’s safe. The static shock can be a PITA, but there are ways around that.

Go ahead and use it if it’s cheap in your area.

I have read that plastic has a natural “drag” to it, and metal is the best. You lose a little CFM with plastic I’ve read. Metal is inherently anti-static. There are anti-static grounding kits sold everywhere if you go the PVC route.

-- Odie, Confucius say, "He who laughs at one's self is BUTT of joke". http://woodstermangotwood.blogspot.com/ (my funny blog)

I am using 4” PVC. I grounded both inside and out and tied to the cold water pipe that is in my shop. I am planing on re-working my dust collection to my shop. When I do, I am going to pull out the grounding wires from inside the pipe and just leave the wires on the outside. The wire inside of the pipe catches too much junk.

This has been discussed mutiple times on this site and the conclusion seems that you don’t need to ground at all. However the DC will then be prone to static electricy dischages to the end user. :) I don’t like that and have already invested in the wire so I am going to use it to help keep this end user from getting litely zapped all of the time.

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

Odie, I could believe the drag factor. I wonder if Blankman has a calculation for that too. lol

One thing I didn’t like about the plastic it always accumulated dust on its surface.

But maybe that’s a good feature.

It’s attracting all of the fine dust that gets missed by the suction.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

People overanalize this too much. The only problem you’ll get is static shock if you touch the flex tube from the machine to the pvc. Just wrap a piece of wire around the end, and hook the other end onto the machine you’re using. Problem solved, no more shock since the machine now grounds the line.

I think that running a wire inside the pvc is a bad idea, and could lead to clogged lines.

-- Julian, Park Forest, IL

Dust explosions are mainly caused by extremely poor house keeping. Years of fine dust build up. Blow your rafters off once a month.

-- There's many a slip betwixt a cup and a lip.--Scott

I don’t recommend blowing, you just put more dust in the air that you’re trying to keep from breathing, cough, cough!!!
Use a vacuum.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

I have just been reading this site, which is a bit of an eye opener in terms of dust collection:
http://billpentz.com/woodworking/cyclone/index.cfm

He has a cyclone design you can build from sheet metal as well.

I have 6” PVC, no problems.

-- Chip -- Manchester, Connecticut "When the power of love overcomes the love of power, the world will know peace."

Thanks all,

I will use the PVC and probably rap it with some light copper to negate the PITA factor. With just a little luck I will get this done this summer. The plan is sooner than later but then that is always the plan :)

-- "so much to learn and so little time"..

I’m going to do some overhead ducting myself and I’m just going to run it across and not worry about grounding at all. I’ll have mine nestled right next to my I-beam for the house, so I figure it might bleed off any static on the surface.

-- Bradley Miller, Blue Springs, MO - http://myoldgarage.blogspot.com

Just to complete my thinking on this subject -

The only disastrous dust explosions I ever heard of were not (apparently) the result of the containers or conduits of he dust (IE- the piping) but rather the result of static charges built up on the dust particles themselves.
Consider the case of an explosion in a grain elevator.
It isn’t that the piping is an ungrounded or ungroundable material, it is the buildup of an enormous cloud of dust in the storage silo, usually when the silo isn’t full. That allows for a very large cloud. Think of a volume much bigger than your house and a couple of hundred feet high.
But, you may ask, “where does the static buildup take place?”
Here’s where.
I recently saw a picture of a volcano spewing a cloud of volcanic ash high in the sky. It was in a magazine like National Geographic, I think.
At any rate, the remarkable thing was the tremendous display of “lightning” in the dust cloud. Very much like ordinary lightning, it was the result of the dust particles rubbing against one another.
Now, think about your (comparatively) tiny dust collector.
How much static are you going to generate? Enough to give you a little zing if you touch a PVC pipe? Sure. But I’ve experienced some very large shocks just getting out of the car and touching the door handle. I don’t think, however, that it’s enough to fire off an explosion in the relatively tiny dust cloud in my cyclone DC.
In fact it’s a charge in the wrong place to fire off a dust fire. The dust itself needs to be charged in order to do that and it needs to be larger by orders of magnitude!

Well, I believe that’s the last thing I want to say on the subject. It’s been gone over many times and its unlikely my thoughts will change the minds of those convinced otherwise.

d

-- If a man says something in the forest and there's no woman to hear it, is he still wrong?

To those who are planning on spending time and money “grounding” PVC pipe: Before you spend the time, effort, and money, please read the link posted by WhittleMeThis and myself. Read the entire article, then make your decision.

An interesting side note that has developed over the last few years, supporting the MIT employee’s writings, is the plastic cyclone body. How would you “ground” a plastic cyclone body? ;^)

The fire hazard folks should really worry about are sparks caused by sharpening on the belt sander, blades that hit steel nails and screws, cigarette butts sucked into the system, etc…

-- - Please help keep Lumberjocks an enjoyable escape by refusing to participate in political discussions. Simply spit out the bait and ignore the thread...

CPB, I didn’t even think about cigarette butts, that cracked me up because I know smokers that are dust conscious, lol.

-- -JimmyC...Clayton,NC- "Just smile and wave boys, smile and wave"

I’m not a smoker, but plenty of woodworkers are.

We had a local shop who had a DC fire from a cigarette in the collection bag. The scary part is how long a butt or sharpening spark can smolder in the bag / can…

-- - Please help keep Lumberjocks an enjoyable escape by refusing to participate in political discussions. Simply spit out the bait and ignore the thread...

I learned my lesson about not using the dust collector for metal once.

I was sharpening an old beat up chisel, & all of a sudden my shop was full of smoke.

It was coming from the lower bag of the collector.

I immediately removed the bag, & took it outside.

There was a small 4” patch of sawdust smoldering inside.

I was lucky, because I was just going to take a lunch break.

I could have lost my shop.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

Floor sweeps I’m not sure are a great idea either.

My little fright with smoke and smoldering embers wasn’t in the DC, but it taught me the seriousness of having a smoke alarm in the woodworking shop.
I had been cutting a thick workpiece on the tablesaw, but I had forgotten that there was a blade stabilizer disc mounted on the arbor. Moreover, as is my habit, I was using a zero clearance insert on the machine.
When I raised the blade high enough to cut the workpiece I didn’t realize the stabilizer would rub against the ZCI. But it did. And it created enough heat to start a small ember in the cabinet below.
Just after that I went into the house for dinner.
My wife, whose nose is astonishingly sensitive, remarked that she smelled smoke.
I went into the shop (after searching the rest of the building) and found it filled with woodsmoke. When I discovered where it came from I discharged the fire extinguisher into the saw cabinet and raked out the sawdust that was smouldering there.
My heart squeezed me a bit and I wondered how I would tell Marge without sending her into a panic. I managed to break it to her gently, saying it was a minor matter and assuring her I would mount a smoke detector immediately.
This is only a bit off topic because it still deals with the possibility of losing everything in a fire in the woodworking shop.
Please, everyone, remember that our medium, wood, well dried wood for the most part, is flammable and we owe it to ourselves and our families to be as careful as we can be.

Don

-- If a man says something in the forest and there's no woman to hear it, is he still wrong?

I used to work in a factory that made taillights for cars. When the plastic parts came down the line they were very hot and the plastic firm we put on them generated a lot of static. When we would ship them out in these huge medal containers, you could hold your hand an inch away from it and see the static spark jump from you the box to you finger. It would make your finger hurt. What we did was take a copper wire and attach two clips on each end. Clip one end to the box and the other to something else, BINGO you just grounded the object. I don’t see why this would no work on the plastic pipe.

-- Twenty years from now you will be more disappointed by the things that you didin't do then by the ones you did. - Mark Twain

Don,
I know it’s not a laughing matter, but I just read your comment on this forum. I can picture myself trying to tell my wife, it was only a small fire, nothing to worry about. It gave me a good laugh tonight. My wife didn’t think it was so funny, ...go figure.

-- Mike the CreekWoodworker

I’ve been running PVC for years with out problems,

-- Jim from Heirloom Woodshop Southern Oregon

I’ve seen and read too many discussions on this particular subject. I know it’s a risk to run PVC pipe, but then again so is waking up in the morning. Run the pipe you want and go on living. Worrying about it probably has better odds of harming you or your property than the potential for fire from PVC pipe…

-- Trying to follow the example of the master.

I have had PVC in my shop for years. Because you are always going to hear good reasons to believe either argument, I ran a ground wire through mine from my DC to each tool. I just bought a 50ft roll of 12/2 wire and took the ground wire out, then stripped as much of the plastic insulation off the other wires as I needed to finish the job. I made sure that there is no splices inside the tubing, only at the tool to reduce the chance of a clog. Knock on wood in all the years I have had mine I have never had a clog, I did put in a couple Y’s just in case I ever do then I can just snake it clean. Have fun.
Nate

By chance I listened to an old Wood Talk Online and came across this episode that talks about this topic and gives a nice link that might answer your ?’s a little more. Hope it helps.
Nate
http://thewoodwhisperer.com/woodtalkonline/episode12

404!!!

-- If a man says something in the forest and there's no woman to hear it, is he still wrong?

Snowdog, if you look at the pictures of my shop, I have PVC running along the wall to the bench tools. Never had a problem or even a hint of one.

-- Guy Kroll

I know I started this thread a while back but I just got my PVC up inside the suspended ceiling, now I have to connect all the fittings. Dang I am moving slow on this :)

-- "so much to learn and so little time"..

PVC 25 years, no troubles.

The issues are only for larger commercial operations, home shops do not generate the proper combination of elements to cause problems.

-- Still clinging to my guns and religion.

My father has PVC in his shop, he ran copper wire through it to ground it. The only issue he’s had was when he was planning a lot of pine. The chips are very light and the little bit of static that built up cause the system to clog a few times. He just unhooked the system from the planner while he was planning the pine and swept up afterwards. Just an FYI, static will build up in a metal system too, I’ve been zapped a few times by ours, nothing big though. You should be fine with just PVC.

-- "At its best, life is completely unpredictable." - Christopher Walken