DC Installation question

[Scott Lingle]

All,

Got a simple question, I am working to get a DC in my shop. My question goes for main line length from the DC. I (fortunately) have been blessed with a large pole barn (30 x 46) to work with. I was planning on building a lean-to on one side of the barn to contain things like the DC, air compressor, bathroom, etc. Unfortunately, the placement of the majority of the dust producing equipment is farthest from the side where the DC would live and my main line would have to run ~20 ft before even the first branch. Does anyone here have experience/tips for long runs such as this? My inkling is that with a hobby type shop like mine, I shouldn't have too many problems with a long run but I wanted some verification on this. I've been reading a lot on this topic, and I think my head is starting to hurt.
BTW, the DC will most-likely be an Oneida Super Gorilla - 2HP at the least, 3HP if I can find the money in the budget. While I can possibly move it closer to the machinery, the lean-to was where I would like to keep in.
Thanks,
Scott

[Scott Lingle]

Aw now, cmon, 18,000+ creekers? Someone must have run into a similar problem. Honest, I promise I'll do a photo shop tour when I get it cleaned up...:)

[Randy Klein]

No experience to talk of, but have you checked out Bill Pentz' site?

[Scott Lingle]

Thanks for the reply. I have throughly read his site, yes. I plan on going back in for another brush-up quick before I do buy. There is a lot of information to digest. As I look around, I see some conflicting theorys between the different DC camps, and that doesn't count the manufacturers! I was just hoping to find a little inside information.

[J.R. Rutter]

Well, you can't escape the physics.

I'm on my 3rd cyclone system now. The best in terms of suction pressure was a large diameter blower with narrow side profile. That thing was scary and sucked up everything in reach. It would pull a cat through 100' of 6" pipe, no problem (no, I didn't really try it, but I did have to dig tape measures out of the drum from time-to-time). But open a 3rd gate and it dropped off fast. My current Torit/Donaldson will run lots of open gates (and needs to for good seperation), but doesn't suck as hard if only one or two are open.

A longer run will probably work just fine, especially if it is straight. Every little drop in static pressure lost to ducting means a little less for dust capture. But you can try to make it up on the back end by upsizing the filter and/or keeping it clean and free flowing. Dirty filters are just as bad, or worse than a long duct run.

Another possibility is increasing the main branch diameter slightly. But if you are only running a gate or two open at a time, this isn't a good idea, since airflow will be dictated by the open gate(s), not the main duct.

In the end, I would say just put the DC where it is convenient and design the ducting to make the best of it - diagonal branches, long elbows, no leaks, tight gates, big machine ports, etc. If the 3 HP cyclone blower is larger diameter, not just taller, it will be worth it.

[Scott Lingle]

Well, I'm starting to feel a little more at ease about putting this a little more out of the way now rather than re-configuring the shop. I'm going to go with a dead on straight main line with as few trunks as I can and reduce as I break diagonal trunks off. Also, I'll put gates where appropriate, and apparently, keep my tape measures farther away from the ports.

[Joe Chritz]

If you are thinking about using Oneida call them first.

If you supply a rough sketch of what machines are where and how far apart they will do a full engineer of the system for you. When I go my Gorilla it was a free service and assume it still is.

You can source pipe elsewhere if you wish but I found the prices not to far out from what I could get around here.

They set mine up and I have a run of 20+ feet to the downdraft table. It operates great and is actually one pipe size undersize since I changed the locations of a couple tools. Plus, I had to use a pair of 90's right off the machine to get high enough which robs a bit of flow.

Joe

[Steven Wilson]

20' straight line distance to first branch? Well you're looking at 3hp minimum preferably 5hp and an 8" or 10" main. 2HP won't cut it.

[J.R. Rutter]

20' straight line distance to first branch? Well you're looking at 3hp minimum preferably 5hp and an 8" or 10" main. 2HP won't cut it.

I don't know, even with a little 6" main, that is less than an inch of SP. What does the 3HP Gorilla thing flow at 5-6" SP? I agree that an 8" main would be nice!

[Greg Funk]

20 ft is not that far. If you are running a 7" main at 4000 fps you will lose .76" of static pressure. For comparison one 7" 90 elbow is equivalent to 13' of straight pipe. For some good info on laying out your system download Air Handling's catalog http://www.airhand.com/catalog.asp. They include lots of tables showing pressure losses for different size pipe and fittings.

Greg