Dust Collection Piping

[Graham Flaig]

Hi there,

I recently got a dust collector, 3hp 2320 cfm. I am going to make a dust collection system for my shop to connect to my table saw, jointer, planer, drum sander, router table, miter saw, drill press, and stationary sander. I was looking around and can't find much on pvc and metal piping and was wondering if it was ok to do my entire system using the 6" flex hose. I heard somewhere that it reduces the efficiency from the rigid piping, is this true? I think it will be much easier to use the flex hose throughout the whole shop and just use pvc or metal fitting when i want to change direction. Here is a link to the flexhose I was planning on getting http://www.leevalley.com/us/wood/pag...at=,62604&ap=1

Thanks,

Graham

[Ed Mazuronis]

Couple thoughts. One, there is no way that unit pushes 2320 CFM. Off the top of my head, 3HP and 12” impeller is much closer to 1000 before duct loses. Two, given the real world capacity, I’d go 6” PVC sewer and drain pipe. It’s far less restrictive and much cheaper. I paid $25 for 10’ of SDR-43 today. The distributor was out of thin wall D2729, which is sufficient and around $15 for 10’. Im using 120mm flex the last 2-4 feet of each run.

[Peter Christensen]

Graham flex will add as much as triple the drag of pipe. I play with this calculator for comparisons and with the 2320cfm your specs said using 30' of pipe and 4 smooth elbows the total duct loss was 14". With nothing changed except flexible duct (wires covered) it came out as 23" of loss. Since the specs on dust collectors is greatly exaggerated I did it again at a more realistic 1300cfm. The numbers were 4.4" and 7". So in the example you're looking at half the performance with flex hose over pipe. Use the pipe as much as you can and keep the flex to a minimum.

http://www.freecalc.com/ductloss.htm

Would you put your location (city is good enough) in your profile so we know where you are? It is easier for people to give you supplier information near you.

[Graham Flaig]

Thanks so much Peter, I added my location (Calgary). I have been having troubles finding suppliers for cheap sewer PVC so would love to know if anybody in the area found some.
Thanks for the link, super helpful.

[Peter Christensen]

I haven’t found any cheap PVC myself. $10 to $16 per foot for 6” here and 8” was $16 to $24. Spiral 6” is $6 to $10 which is still painful.

[Ole Anderson]

Welcome to the Creek! I am a big fan of 26 gauge snaplock steel duct, usually easier to find locally than S&D PVC and it is available in one inch increments which allows you to fine tune the duct design. Certainly there are HVAC suppliers/sheet metal guys there?

[Julie Moriarty]

Two downsides to PVC pipe is static buildup and the lack of proper fittings. In my last shop I installed PVC pipe and wrapped it with #12 bare stranded copper. There was still static buildup. In the new shop I installed metal HVAC ducting, both pipe and fittings, except for specialized fittings like Ys and long sweep 90s. I bought those at KenCraft. The metal pipe took care of the static and the system works as good or better than in my last shop. Had I known about KenCraft at the start of setting up the new shop, I would have bought all my fittings from them.

[Ed Mazuronis]

I haven’t found any cheap PVC myself. $10 to $16 per foot for 6” here and 8” was $16 to $24. Spiral 6” is $6 to $10 which is still painful.

You won’t find cheap PVC from the retail suppliers. They typically only carry schedule 40, which is overkill and requires expensive fittings. I had good luck at distributors who specialize in supplying drainage/sewer pipe. They had thousands of feet in stock. Prices ranged from $1.50 to $2.50 per foot.

[Randy Heinemann]

I used steel ducting from Oneida. Since I bought the materials from them, they created a plan for my ductwork which was simple and cut the amount of material I required when compared to my plan. Their material is expensive and I'm sure you could buy it cheaper from another source if you already have a good efficient plan.

The goal with the system is to run as little ductwork as you can and still meet your needs. The more ductwork the more drag on the system.

While it's OK to use flex hose connections from blast gates to tools, use of flex hose for the whole system will most certainly reduce the air flow in the system.

Keep the initial ducting from the collector as large as possible, use reducers that gradually narrow down rather than abruptly, try not to use 90 degree turns (rather 45 degree turns), and only reduce to the size of the tool connection as close to the tool as possible.

I would not use PVC because of the static buildup. Use heavier gauge steel duct material as it will not collapse if you should ever run the system without opening at least one blast gate.

It was a bit more difficult for me to use metal because I'm not an expert in ductwork, but the end result has been worth it.

[Christopher Hubbard]

You won’t find cheap PVC from the retail suppliers. They typically only carry schedule 40, which is overkill and requires expensive fittings. I had good luck at distributors who specialize in supplying drainage/sewer pipe. They had thousands of feet in stock. Prices ranged from $1.50 to $2.50 per foot.

Does anyone know of good suppliers in the Dallas/North Texas area?

[Peter Christensen]

You won’t find cheap PVC from the retail suppliers. They typically only carry schedule 40, which is overkill and requires expensive fittings. I had good luck at distributors who specialize in supplying drainage/sewer pipe. They had thousands of feet in stock. Prices ranged from $1.50 to $2.50 per foot.

I wasn't going to retailers. I went to suppliers that sell everything up to 3' and bigger in multiple materials. I also tried irrigation suppliers too. They were at the lower end of the pipes I quoted and are 100+ miles away. None of the retailers have anything over 4" and what they have is very limited. This is the largest city in this province and it has just over a quarter million people in it so certain kinds of products are limited or aren't sold here. If you want to do some searches for me to find cheaper prices here I'll go look. I've done all that I'm going to.

[Ed Mazuronis]

If you are seriously considering PVC and the suppliers in your area really charge that much, you might want to consider purchasing in the US and have it freight shipped. The 500-1000 spent on shipping would save you thousands in material depending upon the size of your shop. Would be an even better deal if you could find a few local woodworkers to share a load.

[Peter Christensen]

Ed I gave up the idea of the PVC especially with the cost of fittings that I didn’t mention. Pretty much ruled out the metal for cost reasons. I’ll be spending some time making square ducting out of sheet goods, much of which I got for free. Already figured out how to make large radius elbows and wye’s with the blast gates incorporated. I used the calculator I linked earlier to compare the losses to round and there isn’t even a 1” difference. The CV-Max will handle it easily. Shop is 635 sq ft.

[Joe Wood]

Julie, how do spot static buildup? I think I used PVC pipe for my setup, it's a white pipe anyway.

[Ed Mazuronis]

Peter, the cost of fittings is where the real money is. I probably have double the money into fittings as I do pipe. It could have easily been 8 times had I not shopped around for several weeks. Good luck with the metal ducts. I’m considering making my own transitions out of sheet metal as well. I’m tiring of trying to chase down reducers to go from the 6” PVC to 120mm. I’ll call a few local shops first, but I fear they either won’t want to deal with a custom small order or will charge through the nose. Time to buy a pair of snips, rivets, and a ton of band aids!