DC pipe height on wall

[Nathan Callender]

Hey folks, I'm in the process on getting a permit to insulate and finish my garage. I'm currently working on laying out the dust collection. Most of us run the pipe at ceiling height and then drop it down to each tool. However since I'm going to run 4" pipe around only 20 feet of perimeter, I'm wondering if it would be more efficient to run the pipe at mid level on the wall so there is very little vertical lift. It would also declutter the walls as well. I'm going to run the pipe through a super dust deputy and into the blower so mounting the SDD at mid level would make for a shallow dust bin but it would still be workable. And, I don't make enough dust for a small bin to be too annoying.

Talk some sense into me if I'm not taking something into consideration.

[Alan Schaffter]

Here's the thing, if you run the pipe along, first it will preclude you from placing machines, etc. tight against the wall and also require extended flex to reach any machine that you position away from the wall. You will also need 90° bends to run the main around the room. 90° bends are high SP and rob CFM. If you run the pipe along the ceiling you can run ducting from the DC (located anywhere) diagonally or at any angle across the ceiling, then use wyes (45° branch) to drop down to your machines. The only way you'll know what is best is to calculate the CFM of both arrangements using the data on Bill Pentz's site.

[Andy Giddings]

Nathan, is there a reason you're running 4 inch? You're going to lose significantly more performance with a small duct (especially 20 ft of it) compared to a larger size. Most users that have a 1.5HP and above DC use 6 inch to mitigate the loss incurred from duct runs. As Alan states, if you use Bill's spreadsheet you'll see a large difference in static pressure between the two, even when the duct is smooth and straight (something like 9 inches which is enough to reduce the flow on a small DC to little more than zero)

[Robert Engel]

Alan and Andy are bring up crucial points. I recommend you follow their advice.

For years I used 4" ducting and replaced with 6" HUGE difference. Also, generally a central line with Y's off to each machine will be more efficient.

Use Y's and 45's rather than a T or sweep 90. Use 2-45's rather than an L.

I will add:

1) Mounting the pipe lower on wall will limit your use of wall space for shelves, hanging, etc.
2) I think you will find lowering the cyclone and limiting your dust bin capacity will be a PITA.

[James Gunning]

Another strong vote for 6" instead of 4" pipe. Even for 1 HP blowers, the 4" pipe just can't flow enough air to use the full capability of the blower. The 6" pipe has over twice the cross sectional area than 4" has. If you can, upsize the pickup points on your machines to 6" as well. Not always easy, but will result in much better performance. The placement of the ducting is really up to the individual situation you have. As suggested, don't use 90 degree bends if at all possible. If you have to use a 90, make sure its a wide radius one. It's recommended to have a straight length of pipe 4 to 6 feet long entering your cyclone. This allows the turbulent airflow in the duct to "settle down" (become more laminar) before entering the cyclone. It will increase the efficiency of the cyclone slightly. If possible, avoid flex pipe. The internal corrugations will increase the turbulence in the airflow and will raise the static pressure (resistance to flow) in the pipe compared with smooth wall. If flex is the only practical way to hook up something, use the shortest piece possible.

[Joe Shinall]

I am in the process of redoing my entire DC system and I have to give these guys credit, 6" is a HUGE difference over 4 but I know that's not your question. As far as "lift" I don't really think with the suction power of a Dust Collector motor that it will hurt it. I was going to run my 6" pipe lower but then realized how much wall space I was giving up and how hard it was to get it where I needed and up at the 7 foot range seems to work best in my situation. (Only have 7 foot walls in most of my shop)

I am also using a Super Dust Deputy XL and I went way down to a 20 gallon barrel to get my height down because I only have 80" in the DC room. With the 20 gallon barrel, the direct run height out the SDD is about 4 feet which would make a perfect mid room height for the run. But again, I wouldn't recommend it, just letting you know your options.

But if you can, jump to 6. I cannot believe the difference in the suction coming out of this. And I have mine venting outside.

[Nathan Callender]

So where are you all getting your 6" fittings? I'm seeing prices for wyes and elbows in the $20-$25 range. The reason I'm considering 4" pipe is that all my machines have 4" ports. My tables are would be the only machine I could mod to increase the size, but it does fine currently. And I always wear a respirator anyway because there are just too many things that I can't collect all dust from. Sanding, etc.

[Robert Engel]

Yes, the fittings are a bit pricey but there are some fittings like sweep 90's that are upwards of $40. The way I look at it is compared to metal ducts, its still a big cost saving. When you see the diff it makes in the system, its money well spent.

I purchased through a local industrial plumbing supply. Check but I think a lot of them will sell to the public. If not you might find a plumber that will let you order through his company.

I did not increase the port sizes on machines. I ran 6" drops to about 3 feet from machine, then 4" flex to the ports. Also keeping you biggest fine dust producers (drum sanders, miter saw, etc) closest to the cyclone helps.

I think its a good idea to have a portable system for sanding, etc. I use a shop vac with a small cyclone and HEPA filter for the router table, chop saw and orbital sander.

Glad to hear you're using a respirator! I can't stress enough to other ww'ers that 95% of us are just looking to avoid sweeping the floor, not have an OSHA compliant DC system. And even if I did, I would still wear a respirator!

[Joe Shinall]

They are a lot cheaper if you can find a local plumbing supplier. Go with Sewer Pipe. Most places call it ASTM 3034 Sewer and Drain, the green stuff. The Wyes I bought were 17 bucks a piece, the 45's were like 7 or 8 and the pipe was about 35 bucks for a 14 foot section. Even if you stay at 4" on the machine, if you can run a 6" main line then reduce to 5 then reduce to 4 as close as you can get to the machine, then you've upped your CFM by a lot!

[Randy Red Bemont]

Lots of great info. Keeping this all in mind for when I get my new shop built.

Red

[Carl Kona]

Nathan,

You don't mention the size of your blower? Whatever CFM you have now, you will only get about 60% of that after the SDD. As Robert and Alan mentioned use a straight main across the shop with Ys to each machine. And after you have a rough idea of your layout run it through Bill Pentz (or similar) static pressure calculator. You will be quite surprised how much fittings and hose will eat up your available pressure (reducing your CFMs) Are you using a SDD or SDD XL?The SDD only has a 5" inlet. The big box stores sell 5" metal duct. but you will have to get Wyes from someone like Ken Craft (standard HVAC Wyes are backwards for flow/connections) [Oh and I have 4 of their 5" wye's I am looking to sell PM me if interested]. With a smaller blower 2HP or less, you can get buy with the cheaper HVAC ducts 30 gauge from HD or similar. If you stick with 6" PVC you can also go to Menards and have the fittings special ordered from the website and I think delivered for free? They also carry the white S&D pipe so you are not mixing white a green fittings and pipe. If you are planning on the SDD with 5" inlet then 6" pipe would not be the way to go (You don't want your pipe bigger than your inlet). Also, if you don't mount your blower right on top of the SDD then only use 6" hard pipe as short as possible from blower to SDD. Someone had 4 or 5" flex connecting the 2 and his separation was horrible. He simply up-sized the pipe and went to hard from flex and the flow and separation were back to normal!

Hope that helps,

Keep us posted,

Carl