Metal or plastic?

[Wade Lippman]

I have done a search than read several threads on this subject; PVC or 26 gauge steel.
I have a 3hp Grizzly Cyclone, 13x25 shop, and will be putting 4 tools on it now; perhaps 6 later on.
My intent is to run all 6" to the machines, then drop down 4" to connect to the machine.

I can buy steel for $2.10 a foot and PVC for $1.50 a foot. I haven't priced fittings, but assume they are comparable. (If I am wrong; let me know!)

As I see it, steel has the advantage of not building up static electricity. As I understand it, SE can't make anything explode, but can give some nasty shocks. In my old shop I used 20' of 5" PVC flex and never got a shock off it.

PVC is cheaper, easier to work with, easier to modify; but builds up SE.

Is all this about right? If so, then PVC seems to be the clear choice.

Still, I am going to run a survey to see what you guys think.

[Rod Sheridan]

Hi Wade, I can't imagine anything being easier to work with then metal ducting.

I have metal ducting and don't use plastic due to the static shock factor.

Nothing gets your attention like bending down to pick up a piece from the planer and getting a static discharge to your head......After 2 or 3 experiences I went with aluminum flex...............Regards, Rod.

[Paul Wunder]

PVC.

Easy to install

Tight installation (no leaks) without taping, calking.

Less risk of cutting one's self

Readily available fittings

Less internal friction than most metal. Improves air flow

Easy modifications as needed

NO STATIC! What a red herring argument

[Larry Browning]

To me PVC is far easier to work with. It is easy to cut and fit. Also you don't need to glue the joints either, so dis-assembly is easy as well. However the PVC fittings may actually be more expensive than the metal ones. My personal experience tells me that the static elec thing is WAY over stated. I have had my system for 5-6 years now and have yet to experience my 1st SE shock from the system. So, my vote goes to PVC.

[Rick Moyer]

Three years and have never had a static issue with mine either.

[Alan Melbourne]

mine is metal but plastic is ok too. you will have to cut the metal with a mini grinder etc but thats not too bad.
i went for the metal because i started working out the cost and there was very little in it.

i would be carfull going from 6" down to 4".
mine ducts are 6" and i tried reducing down to 4" but it restricted everything too much.
i filled all the 6" duct all the way around with planer shavings. i changed the 4" to a 6" and put a 6" y with a 4"reducer on both sides of the y. the extra air coming in as soon as posible allows the full 6" to pull all the air .
i put a blast gate on the open side of the y . if i close that the pipe starts filling up straight away.

[Bas Pluim]

One thing to keep in mind is that the hose from the blast gate to the machine will be plastic, no matter what material you use for your duct work. That's the most likely area for you to zap yourself (if at all).

[Steve Milito]

To me PVC is far easier to work with. It is easy to cut and fit. Also you don't need to glue the joints either, so dis-assembly is easy as well. However the PVC fittings may actually be more expensive than the metal ones. My personal experience tells me that the static elec thing is WAY over stated. I have had my system for 5-6 years now and have yet to experience my 1st SE shock from the system. So, my vote goes to PVC.

Did you do something to try and have a ground conductor with the pvc or is it au naturale?

[Ole Anderson]

Steel here. Easy to install. Check BORG pricing on 26 gauge snap lock, should be about the same as you are getting for PCV, $1.50 per foot. Also available easily in one inch increments. Best if you go with a 7" main and 5" drops to your 4" hoses. Try that with PVC. Ever seen a professional install with PVC? Moving pipes? Just cut the tape, drill the rivets and away you go. Try ungluing or uncaulking PVC. 6" PVC is OK if you are running a 5 hp collector, not so much with a 2 or 3 hp unless you have short runs.

[David Kumm]

The choice is really only valid for 3 hp 14" systems or less. While it may create less resistance than equal sized steel, the lack of 1.5 ot 2.5 radius fittings takes that advantage away. If your system is larger steel optimizes it better. Dave

[Rod Sheridan]

One thing to keep in mind is that the hose from the blast gate to the machine will be plastic, no matter what material you use for your duct work. That's the most likely area for you to zap yourself (if at all).

\

Exactly, that's why I indicated that I replaced it with aluminum flex..........Rod.

[glenn bradley]

It used to be that price was a driving force. PVC prices are nearly double since I put mine in 3 years ago. PVC still has the advantage of ease of working/changing/modifying but, that is subjective. All my hose has a wire helix. I hadn't seen hose in those sizes that were all plastic(?). In the winter we get some dry weather and something moving through the duct in those conditions will develop a charge. All that is required to never experience a static shock is to make sure that something is an easier path to ground than you are.

[Andy Fox]

6" PVC is OK if you are running a 5 hp collector, not so much with a 2 or 3 hp unless you have short runs.

Why is that?

[Robert Payne]

I'm another PVC proponent and have found that either silver HVAC tape or a length of stranded wire wrapped helically around the duct will pick up the static charge; add jumpers around blast gates and connect crimp connectors on the wire coil ends of flex duct to get any charge they carry and then route one or more locations to ground to dissipate the static without ever getting zapped. Even though PVC is a non-conductor, a fairly substantial static charge will build up from the moving particulates inside the pipe, but this bleeds it off before your get a jolt. The other advantage of price, internal smoothness, tight joints and easy modification all add to the advantage side. I've used PVC for nearly 20 years (first 4" and later 6" when I upgraded my DC). My blast gates are all ClearVue and they fit PVC perfectly. Just my .02

[Larry Browning]

Did you do something to try and have a ground conductor with the pvc or is it au naturale?

Nope, no grounding conductor. I think maybe one time I felt the hair on my arm raise a bit when I was close to one of the ducts, but it has never shocked me.