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4 inch PVC okay for a small dust collection system?

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Forum topic by jtm posted 12-29-2014 08:11 PM 1144 views 0 times favorited 12 replies Add to Favorites Watch
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jtm

218 posts in 1096 days


12-29-2014 08:11 PM

Hi folks.

I’m in the middle of planning out my PVC dust collection system.

I have two clusters of tools, so I really only need two main drops. Ideally, I planned on using 6” PVC for the main lines, but after pricing out fittings and pipe, I’m having a hard time justifying the prices – especially compared to the 4” equivalents.

Will 4 inch PVC dramatically reduce the efficiency?

For reference, I have a Grizzly 2HP 220V G0548ZP dust collector capable of 1700cfm. I’ve been using standard flex hose, but I want to pipe in PVC for a more permanent solution. The total distance with PVC should be about equal to the flex I was using before, and that worked fine for my needs.

Thanks in advance.


12 replies so far

View WhyMe's profile

WhyMe

610 posts in 1020 days


#1 posted 12-29-2014 10:13 PM

You should see better performance with the 4”PVC over the flex because of less resistance. What type of 4” PVC pipe are you thinking of using?

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#2 posted 12-29-2014 10:24 PM

When you compare the prices, it’s important to make sure you’re checking the right size. The stock that’s cheapest and still plenty stout for DC is always labeled ASTM D 2729. It’s called by several other names: thinwall, DWV (drain, waste,vent), soilpipe, and who knows what else. But eh rela cost difference will be in the fittings. Anyway, 4” ducting will carry about 400 (+/-) no matter whats sucking on it. 6” will allow up to maybe 1000 CFM with enough DC. That said, a lot of guys have 4” and completely satisfied with the performance. As mentioned, reduce the flex as much as possible, it has about 3X the drag on air flow of smooth pipe.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Bill7255's profile

Bill7255

352 posts in 1744 days


#3 posted 12-29-2014 10:29 PM

The answer to your question is yes, it will drastically reduce your system capability. 4” will have much higher loss and reduce both CFM at the tool and velocity. Even though the specs of you system claim 1700 cfm, it can’t do that through a 4” line. Most likely the best you can get is 350-400 cfm. Using 6” you will almost double that.
Advice is to go 6” and keep any 4” runs as short as possible.

-- Bill R

View johnstoneb's profile

johnstoneb

2143 posts in 1632 days


#4 posted 12-29-2014 10:32 PM

I am running 4” PVC with an 1100 CFM collector and I am completely happy with it. I only have one tool at a time open.
6” will be much more efficient but if you only use one tool at a time you probably won’t notice a difference

-- Bruce, Boise, ID

View Troy Cleckler 's profile

Troy Cleckler

384 posts in 830 days


#5 posted 12-29-2014 10:46 PM

I have the HF 2hp motor, using a cyclone I built some years ago, and I’m not sure what CFM it’s pulling but it works for one tool at a time. Could it be better if I use 6” trunk lines, maybe but I’m happy with the performance and the 4” was what I had to work with.

-- Troy. - Measure twice, cut once and fill the gaps....

View bigblockyeti's profile

bigblockyeti

3663 posts in 1180 days


#6 posted 12-29-2014 11:57 PM

If the PVC hard pipe is close in total length to the flex hose you are currently using, performance should increase as you will have less air flow restriction with a smooth walled pipe vs. a flexible hose.

View RobS888's profile

RobS888

1984 posts in 1304 days


#7 posted 12-30-2014 05:02 AM



The answer to your question is yes, it will drastically reduce your system capability. 4” will have much higher loss and reduce both CFM at the tool and velocity. Even though the specs of you system claim 1700 cfm, it can t do that through a 4” line. Most likely the best you can get is 350-400 cfm. Using 6” you will almost double that.
Advice is to go 6” and keep any 4” runs as short as possible.

- Bill7255


So will one get 400 cfm each out of two 4” pipes hooked up to an 1,100 cfm dust collector. I mean 6” from dust collector split into 2 4” inch PVC pipes.

-- I always suspected many gun nuts were afraid of something, just never thought popcorn was on the list.

View daddywoofdawg's profile

daddywoofdawg

1010 posts in 1034 days


#8 posted 12-30-2014 05:48 AM

If you trunk line it 6” and 4” down to your tool it will work better than just 4” all the way.
Also ground your pipe,the sawdust going though causes static electricity,and can give you a nice shock on a dry day.

View jtm's profile

jtm

218 posts in 1096 days


#9 posted 12-30-2014 07:34 AM

So I decided to go with 4” PVC for a couple reasons:

Cost – I was able to buy the pipe and all the fittings for my entire system at Lowes for less than the cost of ONE 6” wye at the local plumbing supply house. I’d probably need about 10 feet total of 6” PVC for a main trunk. But that is where all the fittings would need to be (45’s, wyes, etc. for two branches). It would literally cost 6-8x the price of the 4” PVC.

Usage – it’s only a small hobby shop in my basement. Up to this point, I was using the flex lines from the Harbor Freight dust collector kit. These seemed to work fine, so I’m not sure what gains I’ll see by moving to the 6” PVC. For comparison, the total length of my system is still probably shorter than the 4” branches that some people have coming off of a 6” trunk. I also have blast gates at each tool. and I’ll only be using one at a time.

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#10 posted 12-30-2014 12:20 PM

No doubt about it; 6” is a lot more expensive. In PVC it’s also a lot harder to find. What matters is that you’re satisfied with your choice, all other info is superfluous.

-- Our village hasn't lost it's idiot, he was elected to congress.

View RobS888's profile

RobS888

1984 posts in 1304 days


#11 posted 12-30-2014 12:31 PM



If you trunk line it 6” and 4” down to your tool it will work better than just 4” all the way.
Also ground your pipe,the sawdust going though causes static electricity,and can give you a nice shock on a dry day.

- daddywoofdawg


I was thinking along the lines of 2 long runs each of 4” . By long I mean about 20 feet each. Currently, we have a 50 gallon barrel as a second stage, then a straight run to a Y with blast gates that go to my wife’s lathe and to the garage for me.

I’m curious if having a 6” inch pipe to the second stage then 2 4” pipes coming off the barrel would provide 300+ cfm to each line instead of us trying to share the current single line.

-- I always suspected many gun nuts were afraid of something, just never thought popcorn was on the list.

View MrRon's profile

MrRon

3926 posts in 2703 days


#12 posted 12-30-2014 03:43 PM

Use the green 4” PVC drain and waste pipe. It’s a lot cheaper than sch 40 PVC and easier to adapt to DC’s and gates.

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