PVC Dust Collection Issues

Woodworkers discuss pipe diameter compatibility and fire risks with PVC dust collection ducting. October 16, 2012

I am trying to put together a dust collection system for a small shop using PVC. I cannot find an adapter to connect 4" DC hose to the 4" PVC fitting. I purchased some adapters from Peachtree which were supposed to do the job, but they do not work with the schedule 40 PVC used in this area (Northeast). Any suggestions?

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor J:
If yours is a professional shop and open to a potential visit from the local fire department, OSHA inspector, etc., you're not going to do well with PVC piping.

PVC is popular in home hobby shops, so you may find some good info on the hobby sites. They usually have tons of advice on hooking up PVC systems.

From contributor S:
Use metal duct work. PVC or rubber creates static electricity which may cause a fire.

From contributor B:
From a block of wood about 3" thick, cut a circle with a diameter about 1/4" less than what you want the diameter of the PVC to be. Put the wood circle in the end of the PVC pipe and use a heat gun to melt the PVC around the wood circle. Let it cool and you should be ready to go. If you use something other than a heat gun to speed up the process of melting the PVC, use extreme caution.

Or buy some aluminum blast gates to use as transitions from the PVC to the flex hose. To get the blast gate to fit snugly into the PVC you will need to wrap some rubberbands around the flange of the blast gate.

Don't forget to ground the entire system.

From the original questioner:
Thanks. I think I'll go with the aluminum blast gates. Resizing PVC sounds kind of daunting.

From contributor X:
I've heard of static leading to possible fires but I've never met anyone who had a static fire. I never even met anyone that knew anyone who had a static fire. I guess there could be a first, and who the heck wants to be the first to have a static fire? If anyone has PVC static worries, just run a piece of wire through it and ground it. if your machines are made of metal and your metal machines are sitting on concrete, they're probably grounded. Or if they're plugged into a grounded receptacle. All that said, if it makes you feel better, run a piece of wire through the PVC and ground it.

From the original questioner:
Thanks for your input. From what I've been able to gather, this PVC/fire hazard thing appears to be a myth. No one, it seems, is able to recount a single instance of a PVC DC system exploding or catching fire. I found a study done by a guy from MIT about this.

From contributor S:
Well fellows, I had a static fire. I run 16" spiral duct with 9000 cfm. On one machine where I had too long of Canaflex tubing hooked up, we noticed it was sparking on the spiral duct. Before we knew it, the bag house was burning. If you're running small stuff, it probably doesn't matter. 500 -1000 cfm.

From contributor V:
Run a copper wire through the PVC and connect the end to a grounded machine. Any static will dissipate into the wire before it can build up a dangerous charge. There is no such thing as too much safety.

As to your pipe fitting issue, just wrap the male fitting with a little duct tape to bring it up to the size of the female fitting. I use a few ABS and PVC fittings around the shop to bring dust hoods into the galvanized collection system. I've used the tape trick for years to solve this problem.

From the original questioner:
I've been able to solve most of my connection problems with rubber "no hub" fittings and, yes, duct tape. Thanks for the help.