PVC piping -- OK for dust collection?
Plastic pipe systems are not designed for dust collection use. A necessary diversity of fittings to meet design requirement does not exist. Also, plastic pipe elbows have a very short radius and plastic tee fittings are improper for dust removal. It is these types of problems that lead to an inefficient dust collection system.
With a metal dust collection piping system, static electrically won't develop. Elbows and other various fittings are properly designed for conveying dust. The diversity of fittings and accessories will enable you to meet design requirements.
I have found no problems using schedule 40 PVC. You do need to run a ground wire to each machine. As far as elbows are concerned, you can use electrical sweeps, which ease the bends. Also, don't use tees, use Y fittings.
I used plastic in my first shop. The static electric buildup was amazing. I tried to control it with ground wires, but still had problems. Don't take a chance on a dust explosion--use metal. Commercial heating contractors often stock the spiral duct and fittings since they are used in big buildings for air handling.
The National Fire Protection Agency recommends non-combustible ducting when conveying combustible material. As we know, wood dust is combustible, as well as PVC pipe, never mind the static buildup, which is a source of ignition.
When we create a duct system, the interior should be as obstruction-free as possible. A copper wire will snag chips and curls. In addition, many extraction systems are abrasive, such as the conveying of hardwood chips. This material will wear the copper wire.
When we had a PVC system in our shop, I had a chance to discuss the plastic pipe/static situation with an electrical engineer well-versed in industrial issues. According to him, there is virtually no way to protect a plastic based system. The static builds on the surfaces (inside or out) of the pipe and nothing but a continuous metallic ground (more like a coating than a wire) inside the pipe would mitigate the static buildup. He convinced me to get rid of the plastic and redo our system with metal pipe and fittings.
While removing the plastic (prior to a metal install) on a Monday after a non-working weekend, I noticed that the pipe still held a charge from the previous Friday's work. As a precaution I put on light duty rubber gloves. I got zapped right through the gloves by the static discharge from a length of pipe connected to the planer, which had been working hard the previous week. A few minutes later I picked up a piece of pipe that had also been connected to the planer and watched as a large spark arced from the pipe to my chest. These shocks were not life-threatening, as the discharge was mostly voltage with little amperage. That said, they made me painfully aware of the potential for static build-up.
You may get away with a plastic system for years, but some day when you are collecting large quantities of fine dust through your new wide-belt sander, disaster may strike. I'd never consider using anything but metal pipe for dust collection.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
I have seen some air pipe burst causing shop damage and narrowly missing the owner. Luckily, no one was injured.
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