# Size Piping to Use?



## Brian Briggs (Dec 23, 2019)

Newbie here and newbie to woodworking as well. I am setting up a wood workshop in the corner of our building. I have a Woodteck Dual Bag dust collector that I got off of Facebook Marketplace. It is a 3hp 115 or 230 with a 6" input. It came with a dual 4" and a triple 4" inlet adapter. The dust collector is located in the back right corner. I plan to run 4" or 6" pipe along the top of the wall along the cabinet wall and french cleat wall and a drop to the table saw. I may make it a "P" shape so I have continuous flow. I used this when I ran water and airline in my granite shop so the end of the run did not starve for air / water. My question is; Should I run 4" or 6" SDR 35 piping? I am thinking 4" will be fine but want to know from people that know more than I do about it. Thanks in advance for your help.


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## Dave Mills (Dec 4, 2019)

The cfm math works out such that you should keep the largest possible pipe diameter, with the least number of bends and shortest length, for as long as you can. So the 6" pipe up until you're needing it to be 4" for the tool. Even make the turndown from the ceiling to the wall a 6" fitting, then adapt down to 4" close to the saw.


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## difalkner (Nov 27, 2011)

Welcome to the forum, Brian! Add your location to your profile so it shows in the side panel.

You'll get mixed responses but you'll probably do fine with either 4" or 6". There are advantages and disadvantages to both - 4" is less expensive, 6" flows more air, etc.

We have the HF 2HP unit and I move a 20' long 4" hose to each machine as I run them and it does what I need it to. But you have a higher CFM unit so 6" might be the way to go for the runs and 4" for the drops. 

David


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## epicfail48 (Mar 27, 2014)

Go with the largest size you can for as long as you can, i.e stick with whatever size your DC has at the inlet for as much of the run as you can, and reduce that down as close to the tool as possible. In your case, run the 6" pipe and only reduce to the 4" as close to the tool as possible, for best air flow


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## ducbsa (Jul 6, 2014)

This post has some useful links: https://www.woodworkingtalk.com/f32/piping-210123/#post2032843


Depending on the flow rate of the fan, the duct could be too big and the velocity would be so low as to allow the dust to settle out and plug the duct.


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## Catpower (Jan 11, 2016)

Use 5 inch if you are in between cfm of the fan curve


Also beware of the CFM ratings, #1 there is no such animal as a 3 hp 120V induction motor, which is what is pictured


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## Tool Agnostic (Aug 13, 2017)

Whatever you use, and however you put it together, think about how you will clean it out periodically, and how you might retrieve small parts that get sucked up during sawdust cleanup. They don't always get to the dust bucket at the end of the line.


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## jeff100 (Nov 20, 2019)

I'm setting up a similar duct setup as you are except not doing the "P" shape design. About the same length runs as well. It will be interesting to compare once we both get them finished to see just how effective the "P" shape design is (you might have the right idea). I using 4" DWV sewer pipe (10ft for $10 at lowes/home depot) on all the runs until right near the machines where I switch to the Harbor fright 4" flex hose. I've looked around and for a clear 4" with metal wire coil you cant beat 10ft for $15 at HF. They never seem to have it in store so its a online order kinda thing. 

As far as cleaning periodically, what about using a chimney flu brush setup like a pipe snake with a drill. hopefully you get what im trying to explain. you could turn on the blower and run the flu brush to clean out all the nooks and crannies of the system. ive never tried it but it sorta makes sense that it would be effective.

looking forward to seeing how this comes along.


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## Catpower (Jan 11, 2016)

jeff100 said:


> I'm setting up a similar duct setup as you are except not doing the "P" shape design. About the same length runs as well. It will be interesting to compare once we both get them finished to see just how effective the "P" shape design is (you might have the right idea). I using 4" DWV sewer pipe (10ft for $10 at lowes/home depot) on all the runs until right near the machines where I switch to the Harbor fright 4" flex hose. I've looked around and for a clear 4" with metal wire coil you cant beat 10ft for $15 at HF. They never seem to have it in store so its a online order kinda thing.
> 
> As far as cleaning periodically, what about using a chimney flu brush setup like a pipe snake with a drill. hopefully you get what im trying to explain. you could turn on the blower and run the flu brush to clean out all the nooks and crannies of the system. ive never tried it but it sorta makes sense that it would be effective.
> 
> looking forward to seeing how this comes along.



If the duct work is sized properly and you have enough air movement the inside should never need to be cleaned


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## epicfail48 (Mar 27, 2014)

Catpower said:


> If the duct work is sized properly and you have enough air movement the inside should never need to be cleaned


You can say the same about toilets and kitchen sinks, but plumbers stay in business. Always better to have a way to clean things out, though I do agree that routine cleaning shouldn't be needed unless your collector is starved for air


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## Catpower (Jan 11, 2016)

epicfail48 said:


> You can say the same about toilets and kitchen sinks, but plumbers stay in business. Always better to have a way to clean things out, though I do agree that routine cleaning shouldn't be needed unless your collector is starved for air



But dust collection systems have dry sawdust going through them, the other stuff sometimes is a little sticky LOL


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## DrRobert (Apr 27, 2015)

From experience doing 3 CD systems/remodels and some research I've concluded 6" is the minimum for any blower over 1.5 HP/1100CFM. 4" will be too restrictive I know this was the case with my original system. Going to 6" ducts was a serious upgrade in performance even with the small 1.5HP blower I have. In fact, I was preparing to go to a 3HP blower because I am using a cyclone but gave it a try and was very surprised. All I can say is it does the job and I'm still using it.

Your 3HP blower could easily handle 7 or even 8" ducts. Keep ducts big as far as you can before reducing, long sweeping 90's or 2x45's.

Venting outside is another option sometimes available that will enhance performance. Considerations are your location & heat loss. If this is not possible I recommend getting rid of the bags they are extremely inefficient and will prove to be a hassle emptying and cleaning. I would recommend either a cyclone or canisters type filters.

Forums can be a good or bad source of info, so I would suggest you do a little research and learn about CFM, static pressure, air velocity, filter bags, etc and how these are affected by duct/blower sizes.


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