4" vs 6"

[Joe Shinall]

Ok so I've been racking my brain over this 4" vs 6" dust collection. I have a HF 2HP DC and I'm planning on a Wynn filter and Thien Baffle. I priced out PVC and I am NOT paying $35 per 10 foot section for 6". I have a small shop, just 20 x 20. Would 4" work or do I need to look into stovepipe for 6"? I will have 6 runs all together, the longest being about 35 feet. Trying to do this on a budget because I need to get it done quick and just don't have the time to save up and do what I would like.

[Joe A Faulkner]

Joe, you might check with your local plumbing supply house for schedule 40, 6" PVC. I believe this is what many use for DC.

[paul cottingham]

do the math, save your pennies and go with 6". The collection capacity seems to be about double. I have heard that 6 in. 26g pipe with hvac tees is a reasonably priced way to go.
I am no expert (witness all my questions re. this in this forum,) but I know one thing for certain....If i could run 6" duct, I would.

[Matt Benton]

Trust me on this, if you are going to have that much ducting, run through Phil's baffle AND go though a filter, 4" is not an option. Honestly, I'm not sure how well that DC will handle that configuration even with 6" ducting.

Can you exhaust outside? If you want that DC to handle a full shop setup, its almost a necessity...

And to answer your question, you need ASTM 2729 Sewer and Drain (S&D) pipe. It is cheaper and lighter than standard PVC pipe (Schedule 40), and the fixtures are much cheaper...

[glenn bradley]

+1 on ASTM-2729. Less expensive than schd 40 and running 4" solid duct just seems like a waste of time and money. I think you would be dissatisfied and end up having to re-do the whole thing later.

[paul cottingham]

Another thing to consider is whether or not you can fit 6" to that DC, that is the problem I face....if I remove the wye, there is a 6" in. port but with a 4" restrictor. So.....I'm stuck with 4".

[Dave MacArthur]

ASTM 2729 Sewer and Drain (S&D) pipe +1!

Don't waste your $$ on 4", the CFM is twice as high for 6" about. The ASTM isn't usually avail at HD or Lowes, you get it at specialists--in my area you can buy it at John Deere Landscaping. Much cheaper, lighter, and more importantly the fittings are much cheaper!

There are 10-15 threads in workshops about DC piping, and without fail this is the answer. This problem has been solved so many times, that it would be a sin for the 4th level of Hell to put in 4" PVC or 6" sched 40.

[james glenn]

I am working on setting up a similar system to this and am leaning toward the 6" s&d.

However, in my research thus far. The thing to consider is the dust port at each tool.
If you are going to use 4" branches off of the main, then you have lost the benefit of the 6" main.
So each tool needs a full 6" dust port as well or, one would need to make multiple branch pipes which would then equal the volume of the 6" pipe. Is this correct?

Another option, one could have another gate open down the line to keep the air speed/volume up?

I am thinking my plan is to locate a few 'vents' off of the main 6" line and use 4" blast gates which will allow enough air to fill the 6" main.
Not to mention help clean the air at the same time.

Please tell me if this line of thinking is correct or am I way off here?


mention

[Bob Riefer]

I just got that same dust collector last week and built the thien baffle into the ring that comes with it. I'm venting directly outside.

I received a bunch of 4" PVC for free from a friend, so I'm planning on using that at this time since I won't be out of pocket anyways. I'll let you know how it goes.

Since I just was looking at the unit during the baffle build... You'd have to modify the unit to allow for 6" pipe. It wouldn't be hard to do, but it's not setup to accept 6" right out of the gate. Just mentioning.

Also, as many tools as possible would also need to be modified for 6" pipe (else the benefit of the 6" pipe gets restricted to the smallest pipe open on the run anways).

Side note: Although I'll get slammed for saying it... I've been in a lot of shops that are using 4" pipe and it's working nicely in each case. I use a respirator while working, so my DC is mostly for keeping the mess in check.. that being the case, I'm fine with the smaller pipe size. 5 years from now, if I change, oh well - hanging pipe is one of the easier tasks to have to re-do in my opinion.

[Curt Harms]

I'm running a Penn State "2 h.p." machine set up like you're planning--Thien baffle & Wynn filter. I've done 6" 2729 PVC and home made 6" blast gates. Part of my reasoning for going 6" is that I have to use 10' of 6" flex hose due to everything being on wheels. Without doing research I figured with the turbulence inherent in 6" flex hose there's enough airflow degradation that I didn't want to further degrade performance by undersizing the fixed plumbing. There does seem to be enough airflow velocity that chips don't fall out of the airstream which was a concern with a smaller machine to large ducts. For a garden variety D.C. I'm quite happy with it.

[Rick Moyer]

Side note: Although I'll get slammed for saying it... I've been in a lot of shops that are using 4" pipe and it's working nicely in each case. I use a respirator while working, so my DC is mostly for keeping the mess in check.. that being the case, I'm fine with the smaller pipe size. 5 years from now, if I change, oh well - hanging pipe is one of the easier tasks to have to re-do in my opinion.

And this is the larger point that the OP didn't mention. Is he trying to reduce mess or is he trying to improve health? I suspect the 4" will work for reducing mess, but to reduce the fine particulate in the air he should to go bigger and better.

[David Helm]

The 6 inch ductwork for my system is snaplock HVAC ducting. It works well and is dramatically less expensive than the PVC.

[Dan Friedrichs]

if I remove the wye, there is a 6" in. port but with a 4" restrictor. So.....I'm stuck with 4".

Huh? Your 6" inlet is actually only 4"? That's strange.

On the vast majority of these bag-type DC's, the "plate" with the main inlet hole in it is just screwed onto the blower housing with about a dozen little screws. Take them out, take the plate off, and replace it with a plywood disk with a real 6" hole in the center. There you go - 6" inlet.

[paul cottingham]

yes, there is a plate welded in with a 4 in. hole in it. So my effective port size is 4 inches. I am nervous of burning out my motor by replacing it with a plate with a six inch hole.

[Matt Benton]

I've built two cyclones now with the HF unit. In both cases, I did essentially what Dan describes in order to match up with the 6" hole in the top of the cyclone.

No problems in either case....