Use metal or pvc for dust collection pipe?

[Benjimin Young]

There are a lot of posts on dust collection and piping but I am still wallowing on a decision.

System

My DC is a 10 year old 3hp, Craftex, twin 1 micron felt bags, 12" impeller, 6" main with a 3 x 4" adapter. The spec is 2200cfm however I measure 800-1000 at the 6” main with a cheap meter. Up to now I leave one 4” port open, one closed and the 3^rd has a 4” vinyl flex pipe to a Veritas Cyclone lid on a Brute heavy duty plastic garbage can.


Changes I am making
I got rid of the Veritas and installed an Oneida Super Cyclone XL mounted on the Brute garbage can with a 1” wood lid. I have not done the piping yet. (Future full ducting throughout the whole shop is on my to-do list, item 147 I think LOL)

For now it will be very short and simple from DC to cyclone; from the 6” main of DC to cyclone about 9-10 ft including 3 elbows. I plan on re-attaching the Craftex 3x4” adapter to the Cyclone intake and run my well used 4” x 20ft vinyl flex from there to my tool(s). I might still need to keep one 4” port open so the Brute Can does not collapse (TBD).

Detail of piping DC to cyclone

I can purchase either 26ga 6” round housing duct (not spiral) or 6” pvc pipe, price difference for this small run is not important. I have metal adapters for the cyclone and DC for either option so no issue there. The part I am not clear on is air leakage at joints etc.….


Questions

For metal duct will I need to tape all metal joints including the elbow swivels (i.e aluminum tape) , favored option as it is not as permanent.

For pvc will I need to glue the joints? I don’t like the idea of permanent glue in case I need to tweak the install later.
You opinions would be much appreciated…. metal vs pvc for this DC to cyclone short run, assume 800-1000 cfm at cyclone.

[glenn bradley]

Lots of discussion on this. Search like so:

duct site:www.sawmillcreek.org

You will find a lot of answers, prejudices and opinions. ;-) I use PVC and am so glad; light, easy to change and relatively inexpensive.

[Ken Fitzgerald]

I used metal. I am glad I did.

It's like so many things in woodworking. There is no right or wrong. It's a matter of personal preference. What is right for you?

[Brandon Conover]

My setup is all pvc and no complaints. I just don’t like working with metal ducting to begin with so I opted for pvc. Tons of fittings available, easy to glue up or tape together. Can’t go wrong with metal but for me pvc was the better option.

I did did all my the supply lines from my compressor in pvc as well, couldn’t be happier

[Larry Frank]

Mine is 6" DWV plastic pipe and I taped the joints.

[Dennis Ford]

I used 6" DWV also, no glue or tape, just a little silicone caulk

[Jim Becker]

This is more or less a subjective decision...both metal and PVC can be used to build great dust collection duct networks. My personal choice was 26 gage metal.

[Curt Harms]

I did PVC mostly due to familiarity. One thing I did to make transitions (pipe to hose) simpler was to make my own blast gates. One side has a cut in half 6" coupler, the other side uses an HVAC fitting that fits 6" flex hose perfectly. The blast gates are wood, the sliding surfaces are smooth tempered hardboard.

[Robert Engel]

I used PVC for my ducts mostly to save money. Be sure to use thin wall (Sewer and drain). Some of the fittings such as sweeps can be quite expensive so use Y's.

Do not glue PVC. Screw or rivet and tape.

I think its best to mount the blower as close to the cyclone as possible.

[Ole Anderson]

I used 26 gauge snap lock. No regrets.

[John C Bush]

I used 26 ga. snaplock-7" main to 6" runs to 4" drops and gates and 4" flex to machines. Fittings are readily available, and adaptable to vacuum(HVAC blows the other way). I drilled and pop riveted the joints and sealed with the grey joint compound. Seals really well, easier than tape and less $$$. Modifications are easy-drill out rivets and tug on the joints. Tin snips and pronged duct crimpers are all you need. Good luck with your DC

[Wade Lippman]

I used metal, but either is okay.

Small leaks, even a lot of them, are unimportant. Grizzly actually advised me to leave more than one gate open to give the cyclone enough air flow.

[Ole Anderson]

I used metal, but either is okay.

Small leaks, even a lot of them, are unimportant. Grizzly actually advised me to leave more than one gate open to give the cyclone enough air flow.

I don't understand that rationale at all. You want as much suction at the machine, that will force all of the airflow to that machine and produce more airflow where you need it. Bleeding off air at any other place is simply wasting valuable potential airflow.

Ok, if you have a 3 hp blower and you are using it with an 1.25" airhose to your ROS, then maybe...but even then my rationale applies.

[Josh Kocher]

I've got 26 ga metal duct. No issues... goes together easy.
I put a couple screws through connections and then aluminum tape. A couple places I used silicone.
The guy I bought it all from sealed all his elbows with silicone too... It was a real hassle to peel it out and get them moving again where required when I set it up in my shop, so I wouldn't silicone to seal the elbows in case you want to change/move things... tape works fine and peels easy.

[Bill Dufour]

I did did all my the supply lines from my compressor in pvc as well, couldn’t be happier

Note that PVC is spelled out by OSHA as not allowed for compressed air. It will fail explosively in 10-15 years and if you are lucky the sharpnel will not take out too much vital stuff. Metal will fail and either pinhole leak or peel apart but it should last a lifetime if kept dry inside.
If your insurance company ever sees the PVC they will void your insurance before or after the fact.
Of course PVC for dust collection pressures is fine and dandy.
Bill D.