Re: Online Source for 5" PVC Pipe for DC Ducting?

: > It appears that my DC system would be best served by a 5" main trunk, : > with 4" drops to the machines. My previous experience with metal was : > a PIA (leaking, etc.). I would prefer to use PVC this time. : > However, can't find 5" anywhere. My local Borg only carries up to 4" : > and online sources seem to jump from 4" to 6". : >

: > I would prefer not to launch a war re metal vs. pvc, or why don't I : > just get metal since it won't cost that much more. The issue for me : > is not cost but convenience. : >

: > Does anyone know of a source? Even the lightweight cheap sewer stuff : > would be OK for this application, I believe. : >

: > thanks for your help- : >

: > brad : : Hmmm...I just checked McMaster-Carr and usually if they don't have it, you : don't need it, but everything I find there jumps from 4" to 6". Maybe a : local plumbing supply? : : todd : : This site lists schedule 40/80 pvc. It may be expensive though.

Nope, my local plumbing supply got on the phone to a couple of suppliers, but no dice...

Jim, thank you for checking for me. My concern with going with the 6" would be inadequate air flow velocity from my Grizz 2 hp collector. If I was going to compromise, I'd think I'd be better off compromising with 4", since that would guaranty sufficient velocity (though volume would be sacrificed), and it's also cheap and readily available, and nice and light in the sewer-weight stuff at the Borg. I'd still prefer 5" though.

I am running a six inch PVC duct now with my Griz 1029 2 Hp unit... using 6 to 4 inch reducers off the line to a 4 inch blast gate to flrx hose to each machine...

Works fine.... 6 to 4 in reducers are available at the borg... and so is the 6 in pvc...

suction seemed to drop BUT volume has increased...bottom line is I have less dust....

Bob Griffiths

I'm going through the same (re-)design phase myself. One thing you might want to check out with the lightweight cheap sewer stuff is that the inside wall is smooth (some of the drainage pipe I've seen is ridged inside). Ridged walls will add significantly to static pressure drop.

Since you apparently have researched this, are you using a cyclone collector? I am using a trash-can cyclone lid, but I am wondering what the effect of going from 5 or 6 inch to the 4 inch cyclone to the dust collector will do to useable CFM? My DC has a 5 inch inlet, but since the cyclone lid is only 4", it doesn't seem like stepping from 4" to 5" for a few inches is going to help anything.

Let me clarify that above comment for the literalists out there. If my DC system consists of a DC (2 HP woodtek) with a 5" inlet duct, connected to a 4" hose attached to a trash-can cyclone lid, then goes from the 4" cyclone lid to my main duct that I will size to 6", do I really buy anything with a 6" main duct when I am restricting all flow at the source to 4" through the cyclone setup?

No Mark. Your set up sounds fine to me. The transitions should give you enough volume and suction to never notice any problems as long as you're using blast gates at the unused pieces of equipment.

Jim

Hmm, my Borg doesn't carry the 6" PVC, they only go up to 4", but I'm sure the local plumbing supply carries it, and if not, it is available online. But I'm really reluctant to give up any suction. Thanks for the info, though.

I believe the sewer drain pipe I saw at the Borg was smooth inside. It was also much lighter than the Sched 40, which should make installing it much easier.

Sorry, although I have been researching this, I can't answer your question with any authority. I have not been using a cyclone and would prefer not to if I can get away without it. My thinking is that my shop is very small, and that a 2 hp collector should give me all I need without a cyclone, assuming the ducting is right. My experience has been that the fewer fittings and interruptions I put along the way, the better the thing will work. It has tremendous suction right at the collector but seems to die out dramatically only 10 feet away with my current ducting (metal seam-lock stuff I bought when I first put it in several years ago- it leaks everywhere, which is why I want to go to PVC). My sense is that that it won't make any difference, because I would THINK that you're only going to get the CFM that the smallest diameter tube allows as you go from the machine to the collector. But there's a good amount of technical knowledge about DC on this board, and I'm sure someone else will know better.

thanks-

well you are loosing a lot of flow going through the trash can. but air is compressible so if you went from the 5" machine inlet to 6" right away you would not loose too much flow. but if you had the full flow of the machine it would suck the can clean. something to think about.

I could not get 6" at any of the borg's. locally I could get the pipe pretty cheep but the fittings were far more then metal fittings. a wye was 15.00 I think verses a metal 6" for 7.99 and so on. the difference was more then I could manage.

This an incorrect assumption. If you think of this like a water supply system, that would be correct, because water does not compress and it would be limitted by the smallest opening. However, with air and short constriction causes less resistance than a long one of the same diameter.

I Asked the folks at Oneida why the speced a 5" run to a tool with a 4" port, and that was essentially the answer.

I think that your assumption that a cyclone will reduce performance is also flawed. Although, the cyclone will add some resistance, this will be far less than the dust and chips that would otherwise be clogging your filter media, w/o a cyclone (after the first 5 minutes of use).

I'm not an expert, but that's my cut at it. YMMV

-Steve

Forgot to mention that Brad. You can go with a SDR 35 or a SDR 26. Both have the same drainage pattern fittings and SDR 35 is strong enough while being a bit cheaper than the SDR 26.

Do not use the gasketed fittings - the glue on are cheaper and much more effective (smoother barrel on the inside.)

Jim

some cyclones are really inefficient. a well built cyclone will give you maybe