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Using PVC for Dust Collection Systems

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Forum topic by MrRon posted 03-25-2012 08:10 PM 5445 views 1 time favorited 12 replies Add to Favorites Watch
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MrRon

2835 posts in 1901 days


03-25-2012 08:10 PM

Questions frequently pop up about using PVC pipe for DC ducting. The questions usually are in regard to how to adapt the PVC to hoses, blast gates, etc. The diameters are fairly close, but not close enough. Another is how to get wide sweeping 90° bends. 4” PVC pipe elbows are limited to a pretty tight 90° bend so they are not adequate for a DC system as they would restrict flow too much. Bill Pentz, the DC wizard has the answers on his web site on how to make PVC pipe fit DC systems, including how to bend pipe into smooth sweeping bends. His link follows.

http://billpentz.com/woodworking/cyclone/PVC.cfm


12 replies so far

View BlankMan's profile

BlankMan

1487 posts in 2010 days


#1 posted 03-25-2012 09:54 PM

When I was using 4” PVC I had some really long sweeping tees that the curve was way longer then the end of the tee. I’d look for those if they still make them. I’ll look around and see if I have one and take a picture and post it if I do.

And if I remember correctly the blast gates were smaller then the opening say on the end of an elbow but fit nicely in the end of 4” pipe. So if I was putting a gate right on an elbow or tee I’d cut a piece of 4” pipe and put it in there flush first. I’d use silicon caulk/glue what ever you want to call it to glue it in place. Worked great and you could take it apart if you ever needed to with a razor blade. Was a little work to do but could be done.

-- -Curt, Milwaukee, WI

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newwoodbutcher

373 posts in 1507 days


#2 posted 03-25-2012 10:52 PM

I’ve used 4” black pipe to build my system. I used 45’s separated by a 12” straight connector. No problems with that.

-- Ken

View TechRedneck's profile

TechRedneck

738 posts in 1514 days


#3 posted 03-25-2012 11:11 PM

I use S&D 4” pipe. It is inexpensive and easy to handle. Get some good self cleaning blast gates, don’t get the cheap plastic ones.

I would measure the length of pipe you need, cut to length. Wrap the collett of the blast gate a few times with some good electrical tape. This helps make a good seal.

Set your bandsaw height a little over 4” and cut a series of 1” slits in the end of the pipe. Six or eight should do. Slide a good clamp over the pipe and fit over the blast gate. Works great. If you cut the slits too far just wrap one or two turns of tape to cover them then clamp.

I did not glue any fittings. Friction fit every joint and use the “U” shaped clamps to hold the pipe to the walls or

celing. When you have everything the way you like it, wrap each joint with some thick good quality aluminum tape.

If you have a DC with a clear bag. Test the system for leaks by closing all blast gates and turning on the DC. The collection bag should go a little limp. Listen at the joints and gates for major leaks. Some air will pass but not a lot. Don’ run too long like this but long enough to test.

Remember that some blast gates need to be installed a certain way. Check if there is a flow arrow. I made the mistake of installing them upside down and wondered why they were whistling.

Use short runs of flex hose to the machines. If you have to use reducers, reduce at the machine inlet.

-- Mike.... West Virginia. "Man is a tool using animal. Without tools he is nothing, with tools he is all.". T Carlyle

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TechRedneck

738 posts in 1514 days


#4 posted 03-25-2012 11:17 PM

Oh yea.. If space permits use two 45 degree elbows separated by a short length of pipe instead of a 90 elbow.

-- Mike.... West Virginia. "Man is a tool using animal. Without tools he is nothing, with tools he is all.". T Carlyle

View MrRon's profile

MrRon

2835 posts in 1901 days


#5 posted 03-26-2012 04:30 PM

I mentioned Bill Pentz’s web site because his sweeping bends in PVC doesn’t restrict air flow like 45°s and 90°s do. The smoother the inside surfaces of the DC ducting is, the more efficient it will operate.

View KPW's profile

KPW

223 posts in 1026 days


#6 posted 03-26-2012 07:33 PM

Electrical PVC has long sweeping 90’s to accommodate wire pulling. the OD will fit plumbing pipe. You have to get them at an electrical supply house.

-- Ken --------- never try and put 5 lbs. of tenon in a 3 lb. mortise.

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TechRedneck

738 posts in 1514 days


#7 posted 03-26-2012 08:07 PM

KPW. You beat me to it, I was going to recommend the same thing. Those 90’s can be a little pricey, just make sure you get the thinner wall stuff, schedule 40 or less.

I am a Pentz fan, however you will have to cost justify the difference in flow between two 45’s with 1’ between or a sweeping 90. I would bet that there is not much difference. You will notice the most drop in flow with the choice of filter and primary separator.

-- Mike.... West Virginia. "Man is a tool using animal. Without tools he is nothing, with tools he is all.". T Carlyle

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KPW

223 posts in 1026 days


#8 posted 03-26-2012 08:35 PM

Tech, You’re right about the cost. Just thunking like the electrician I am.

-- Ken --------- never try and put 5 lbs. of tenon in a 3 lb. mortise.

View DaveBaker's profile

DaveBaker

65 posts in 2409 days


#9 posted 03-26-2012 09:16 PM

What about static building up when PVC is used? Do you use copper wire connected to a ground to get rid of the static?

-- Upstate New York -- Do what you love and never work a day in your life.

View MrRon's profile

MrRon

2835 posts in 1901 days


#10 posted 03-26-2012 09:42 PM

There have been pros and cons on grounding of DC systems. The consensus seems to indicate that it’s not worth doing.
“you will have to cost justify the difference in flow between two 45’s with 1’ between or a sweeping 90. I would bet that there is not much difference.”
I think a sweeping 90° made from Bill Pentz’s web site costs less than 2-45’s. The idea was to make the inside as smooth as possible by eliminating the humps and dips at fitting joints. Flex duct presents the biggest loss of static pressure and thats where the long sweeps would be used.

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TechRedneck

738 posts in 1514 days


#11 posted 03-26-2012 09:51 PM

KPW may chime in on this, I believe there is equment to bend PVC conduit. Could be tricky DYI with a heat gun unless you are good.

-- Mike.... West Virginia. "Man is a tool using animal. Without tools he is nothing, with tools he is all.". T Carlyle

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KPW

223 posts in 1026 days


#12 posted 03-26-2012 10:22 PM

In the electrical business there were two ways of bending 4” pvc pipe. One was a an electric heater box that you would put the pipe into so it would become flexible and you take it out after a few minutes and bend it to the shape ypu wanted. The other was an electric blanket that wraps around the pipe and heats it up. The trick is to get a good 2 feet of pipe heated up around the whole diamieter otherwise it will kink if you don’t. As far as the static electricity goes it’s really no more than what builds up on a shop vac. I don’t know anyone that puts a grounding system on their shop vac. The only time I could see it being a hazard is if your shop was filled with combustible vapors but then any spark would be a hazard.

-- Ken --------- never try and put 5 lbs. of tenon in a 3 lb. mortise.

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