PVC or landscape duct for dust collection duct?

[Matt Meiser]

Sean, for the latest ones, I just used prefinished maple plywood scraps for the outer parts. I used a beam-type circle cutter to cut a hole for the pipe, then mechanically fastened the pipe from the inside with small screws and caulked. The core is 1/4" material. I cut a U-shaped slot so there are no tricky corners to clean and sandwiched the outer part of the U between the two ends. In practice I've never had any issues with them trying to clog up.

As for static causing explosions, its been debated 1000's of times on the forums. No one has ever cited a real case in a small shop. If you light off road flares in your PVC ductwork, maybe--if you get the right fuel to air ratio, which is unlikely. Grounding PVC is like herding cats--you can try but you won't succeed. Its a non-conductive material.

[Sean Rainaldi]

The drain pipe idea is impractical, as the material is difficult to terminate and rather inflexible.

I hear no mention of spark suppression and grounding in this discussion. Sawdust explosions can take out a garage wall.

Dust goes BOOM!

Yeah I was going to ask about that - should I ground the duct work with copper wire attached from the duct to a copper pipe hammered into the ground outside the garage?

[Sean Rainaldi]

As for static causing explosions, its been debated 1000's of times on the forums. No one has ever cited a real case in a small shop. If you light off road flares in your PVC ductwork, maybe--if you get the right fuel to air ratio, which is unlikely. Grounding PVC is like herding cats--you can try but you won't succeed. Its a non-conductive material.

thanks for the info on your blast gates Matt.

As for grounding, would it be safer then to use metal duct and ground it, instead of PVC?

I have a friend who told me about the dangers, and I often get static electricity shocks from the colllector - can't remember if it was from touching the flexible tubing or what...

[paul cottingham]

Scan through some of the other post on this forum about static explosions, I think this has been pretty much debunked, even the mythbusters couldn't get dust to explode that way. I believe the massive explosions on mythbusters were all set off by flares. Metal is easier to ground, but more costly.

[Sean Rainaldi]

Sean, for the latest ones, I just used prefinished maple plywood scraps for the outer parts. I used a beam-type circle cutter to cut a hole for the pipe, then mechanically fastened the pipe from the inside with small screws and caulked. The core is 1/4" material. I cut a U-shaped slot so there are no tricky corners to clean and sandwiched the outer part of the U between the two ends. In practice I've never had any issues with them trying to clog up.

As for static causing explosions, its been debated 1000's of times on the forums. No one has ever cited a real case in a small shop. If you light off road flares in your PVC ductwork, maybe--if you get the right fuel to air ratio, which is unlikely. Grounding PVC is like herding cats--you can try but you won't succeed. Its a non-conductive material.

Matt,

What size collector do you use?

[George Clark]

The drain pipe idea is impractical, as the material is difficult to terminate and rather inflexible.

I hear no mention of spark suppression and grounding in this discussion. Sawdust explosions can take out a garage wall.

Dust goes BOOM!

Jim,

Unless you can point to a documented case of this happening in a home shop, I believe you are perpetuating a myth. The theory may sound good but reality just doesn't back it up. There are literally thousands of home shops with PVC for ductwork and no documented dust explosions caused by static discharge according to many many on line discussions. Unless you have some documented data, we probably ought to leave this dead horse alone.

George

[Dan Hintz]

To back George's statement up, there was a test I mentioned a number of months back about this very thing... can't recall exact numbers offhand, but it amounted to dust particles of a certain size (a relatively fine grit sandpaper) being created at a rate so high it would take a 36" wide belt sander removing 1/4" of wood per minute in an airstream moving fast enough to keep the airstream saturated with the dust, and so on and so on... followed by a spark. The numbers they were talking about were way higher than any Joe Schmoe could do in a home shop... it was approaching industrial setups before it was a potential problem. With the equipment any of us have (or ever hope to have), it simply wasn't possible to reach that correct dust-to-air ratio for an explosion to happen.

Explosions are something to worry about... just not by us.

[paul cottingham]

Bear in mind, tho' that pvc can give you a good zap when sawdust is running through it. My planer "generates" enough static electricity to raise the hairs on my arm, and give me a good crack if I'm not careful.

Do I worry about an explosion? Not at all. Besides, no-one has been able to explain to me how to ground an insulator.

I get pretty good dust extraction with 4 in. pipe and a 1.5 HP collector. But I really want a cyclone, and want to use it with 6 in. duct. (PVC if it's cheaper.....)

[Matt Meiser]

Sean, I have the Grizzly 3HP cyclone.

[Sean Rainaldi]

I only have a one horse 700 CFM with no cyclone so I think it would be better to use it at the machine for now.

[Alan Schaffter]

So just use the PVC over head and the appropriate PVC elbows and fittings (glued with that epoxy) and quick couple with electrical tape and quick couplers to all machines?

Think that would be the cheapest alternative to the standard dust collection hose?

DO they make quick couplers for 2.5" pvc to 2.5" ports?

DO NOT USE EPOXY or GLUE!!!! Friction fit is fine add a little screw if needed on vertical runs, and seal with a small bead of pure silicone caulk (not latex) applied to the outside of each joint after assembly. If you don't it will be a pain to reconfigure if needed- and it is always needed!

[paul cottingham]

DO NOT USE EPOXY or GLUE!!!! Friction fit is fine add a little screw if needed on vertical runs, and seal with a small bead of pure silicone caulk (not latex) applied to the outside of each joint after assembly. If you don't it will be a pain to reconfigure if needed- and it is always needed!

I just used tape and screws. Works great.