DC pressure

[Paul Wood]

I have a 2HP King Dust collector model KC3108C and was wondering what piping I should use. I have decided to go with 6" metal, but when I asked what guage pipe to use they wanted to know the negative pressure. Can anyone either tell me or suggest a way to measure it
Thanks Paul

[Jason Roehl]

Originally posted by Paul Wood
I have a 2HP King Dust collector model KC3108C and was wondering what piping I should use. I have decided to go with 6" but when I asked what guage pipe to use they wanted to know the negative pressure. Can anyone either tell me or suggest a way to measure it
Thanks Paul

No personal experience here, but I believe the people who have used it have been satisfied with 6"S&D. Whatever the burst pressure is, you can bet the implosion pressure is much higher with a circular cross-section.

[Paul Wood]

Thanks Jason, I neglected to mention I was going to use metal pipe. I have edited the message
Thanks
Paul

[Greg Wandless]

Paul,

Go to the Oneida site and check the gauge on their metal pipe, that should get you started.

http://www.oneida-air.com/

Greg

[Bart Leetch]

Unless you have a big bank roll go with the 6" PVC S&D.

[Dale Sherman]

Industrial gauge would be 22-24 gauge, you could probably get away with 26 gauge or possibly thinner. The smaller the diameter, the less thickness you need. I'm not familiar with the specs on the King model you mention, but at 2hp I expect it probably would max out at about 8"-10" SP. The standard HVAC ducting available at most home centers will work.

If you should happen to close all the blast gates with it running, it is possible to collapse the duct if the static pressure were high enough. Not likely with 8" SP on a 6" 26 ga. duct, though.

Dale

[Paul Wood]

Thanks Guys,
I will try the 22 guage. I bought one length of the stuff from HD and closed the blast gates and it collapsed so whatever it was it was too thin. I priced the S & D PVC and the cheapest I could get was 40.00 for a 10 ft length and the 45's and Y's were between $20 and $40 each. Again thanks for the response

[Scott Coffelt]

I read I think on Onieda that you use 26 gauge for 6" ducting. With a 2HP you should not suck it flat. I found spiral pipe in the KC area for 87 cents per foot. I am using 6x6x6 wye's from HD for $11 a piece and HVAC adjustable 90's that I will turn into 45's. I could not find a good deal on S&D pipe and fittings anywhere in town.

[Dave Anderson]

Originally posted by Paul Wood
I priced the S & D PVC and the cheapest I could get was 40.00 for a 10 ft length and the 45's and Y's were between $20 and $40 each.

OUCH! That seems <b>AWFULLY</b> high for PVC! Metal spiral from Oneida isn't even that expensive and they surely don't give it away.

While I like the ideas put forth by Bill and Terry, it still seems an easier task to use metal ducting and fittings, even from the big-box or dare I put this in print, Oneida.

[Terry Hatfield]

WOW Dave is right....

Those prices are unreal. Are you sure you are pricing S&D and not Sch. 40?

I pay $1.15 per foot for pipe. 45's are $4 and wye's are $10.

If you are going to use metal 26 ga. will be fine.

Terry

[Scott Coffelt]

The price is for 26 gauge metal spiral pipe. The dude quoted us wrong it was actually twice the price, but we were able to get him to come down to $1.42. Onieda was well over $2.00 per foot. I searched locally and there was no place in town who had the same prices you are talking about for S&D. They where in the $20-$30 range for wyes and $10-20 for 45/90's. I prefered to stay with metal and I was concerned that snap lock would implode at 1500 CFM and the DE special. If I could have located the S&D fr a price range like you were talking I would have been all over it.

[Mac McAtee]

Paul,
You say that you colapsed the HD metal duct when you closed all of the blast gates. Just go to the end of your run of duct and make a simple, spring loaded, wood (like plywood) check valve. It would be a piece with a round hole in it. It doesn't need to be very large in diameter, like a 1" or 2" hole, and another round cover, like a manhole cover a little larger in diameter. Put a peice of all thread with a wing nut , a light weight spring of some kind and a bracket to load the spring with the wing nut. You install it so the air flow will pull the manhole cover open. You make this so the OD of the piece with the hole in it is the same as the ID of the metal pipe and you slip it in the end piece of your duct or just put a "T" piece somewhere in the run and let the leg of the T hold this device. You start up your system with one of your blast gates open, no tension on the spring and then adjust the spring tension so that the manhole cover just stays shut. You then close the open blast gate and the vaccume will pull the manhole cover open and allow air into the duct work, in industry this is called a vaccum breaker. You can buy one, they are not expensive. But a few pieces of scrap plywood, a spring, wing nut and a short piece of all thread will do.

You could also build it like this. Take a peice of plywood 6" in diameter that fits into the end of the ductwork or the branch of a "T" drill one hole in the middle that is 1/16" larger than the all thread. For example 5/16" all thread gets a 3/8" hole. Then drill four 3/4" holes at around the middle hole a 1/2" or so away from the middle. Take another round piece of ply wood say 5" in dia., fix a 6" long piece of 5/16" all thread in the center. Put the rod through the center hole in the larger piece. Put a light weight compression spring over the all thread sticking out, a washer and a wing nut. The spring tension holds the smaller disc tight aganst the larger disc with the 3/4" holes in it. Install this in the duct end, just a couple of screws through the duct into the plywood disc.,mount with the all thread sticking out. Then go throught the procedure above to tune it to your system.

[Paul Wood]

Mac, What a great idea!, I will give it a try, also your explaination was easy to follow Thank Paul

[Mac McAtee]

Paul,
Thank you for the compliment. Let us know how it works out.
Mac

[Mac McAtee]

You want to see something that will break your heart, you should see a 150' run of 48" stainless steel duct and all the 36" and 24" branches in a rendering plant sucked flat. Thousands of dollars shot right square in the behind. In very large ducts it is not uncommon to put a rupture pannel in the duct some where. It is like a two or three foot square piece of very thin stainless steel in a frame like a window frame. On the inside of the frame, in the center of the pannel is a knife that points towards the pannel. If the vaccum in the system exceeds a predetermined level the stainless pannel is pulled into the knife and it cuts a slit in the pannel. The vaccume then will tear the pannel open and let air into the ductwork.

I have seen a storage silo that was 12' in diameter and 50' tall cave in. The vents in the top of the tank got plugged and the meat meal inside was being taken out the bottom. The more meal removed from the bottom increased the vaccum in the empty upper part of the tank, squoosh! It looked like a plastic coke bottle that had been run over in the middle of the road!