Dust Collection Duct Layout Advice Needed

Rushton

Rush
Senior User
New shop, new dust collection installation... I need your input on the proposed layout for the shop, with emphasis on the dust collection ductwork layout.

This past year I moved to a retirement community in Huntsville, AL. We're now making serious upgrades to the community wood workshop. My part of the re-design is the dust collection system, which greatly impacts machine locations. I'd appreciate your suggestions on what I've drawn in SketchUp as our proposed layout. Some of you may recall that I installed a Clear Vue CV1800 in my home shop two years ago with great feedback from many of you here.

The dust collector for this multi-user shop will be the Clear Vue CVMAX (5HP, with Wynn Environmental filters) using 8" PVC SDR35 pipe for the main trunk line and 6" PVC thin wall S&D pipe (D-2729) for all the drops. The machines will be mostly Powermatic models. The plan is that we would not have more than two machines in operation at a given time, with only one machine operating at a time (i.e., blast gate open) on any given 6" drop. In this design, I've tried to keep the duct runs as straight as possible, with minimal turns and any 90-degree turns made gradually using 45-degree elbows with some straight pipe in between.

We will install the cyclone and filters in a sound isolation closet, but I have more design work yet to do on that. What you see in the drawings below is just a placeholder design for space planning. I'll make a separate post about the proposed sound insulation closet to ask for your suggestions when I've done some more work on that design.

Our shared use shop is small, about 14' wide by 26' long with 9.5' high ceiling. Fortunately, we have the use of a small side room for additional storage. The yellow rectangles shown on the floors mark 36" wide pathways that we want to keep clear. The pathway marked in front of the cyclone closet cannot have spinning blade tools along it because it is a regular pathway for the community's facilities employees - we want to keep them safe. Because of this "safety zone", it seemed became necessary to locate the cyclone on this wall and let the required 5' of straight pipe leading into the cyclone's intake run over top of this walkway space. (In an earlier draft of the layout, I tried placing the cyclone in a corner so we could run one trunk along the wall with 45-degree drops machines. But we had to abandon that layout when we were told to maintain this safety zone walkway.)

There are no 4" blast gates planned. All blast gates will be on the 6" pipe only to ensure someone doesn't throttle the air flow to the cyclone, not understanding that's what they are doing. (Remember, this is a shared use space and, while we will provide some training/certification to users, we have to plan on varying levels of understanding about the machines.)

Also, I should add that 1) all the machines will be moveable on casters, either locking or retractable. And 2) For the larger volume dust creators, we plan to run solid pipe as close to the machine's dust port(s) as possible. My goal is to have no more than 4' of flex duct connecting the larger machines, but I'm sure we'll end up with greater lengths here and there. And 3) I've not sorted out dust hoods/shrouds, and we will need them for the sanding machines, scroll saw, router table, etc. I will likely experiment with some bell mouth hoods for various pipe ends connections, per the Australian Woodworkers Forum - anyone worked with these?

I welcome and will appreciate your suggestions. Please ask whatever questions you like, as well.

Floorplan A1.PNG


Floorplan A2.PNG


Floorplan A3.PNG


Floorplan A4.PNG
 

kserdar

Ken
Senior User
Hopefully your table saw is mobile or you have 8' clearance from blade exit to the solid pipe in the middle of the room.
Sorry, I missed the " all the machines will be moveable on casters ", but the clearance still applies.
 

tvrgeek

Scott
User
You might check your building code and insurance as I believe PVC in not code. If it is not mentioned, there are a couple solutions. One is running a copper wire through all the ducts. Others stick screws into the pipe every few feet and tie them together to ground. I just used metal.
Waiting on my CV.
 

Rushton

Rush
Senior User
Thanks - good point. Yes, there will be clear cut lines for the table saw past those 6" pipe drops. At least as far as where the fence can sit. Beyond that, the table saw has retractable casters built into the base, so we can move it if we need to.

Here's the sight line. I have room to adjust the drops when we install them and will watch out for this.

Floorplan A5 - clear cut path past dust pipe.PNG
 

Rushton

Rush
Senior User
Thanks for the suggestion to check code for use of PVC. In the U.S., PVC is fine for dust collection pipe in small shops - no code restrictions I've seen for any of the states. I'm not concerned about fire or explosion with PVC pipe at the velocities and volume generated with a 5HP cyclone. In a commercial shop with a 40HP cyclone, that may be a different matter.

But, static can be sufficient for an annoying discharge at times. So, I plan to use the aluminum foil tape process on all the pipe. Inside/outside wrap for the length of the pipe, with circular wrap at the fittings to ensure connectivity. I found this recommendation at Bill Pentz's website and used it in my last shop. I will use the same tape to seal the fittings.

Good comments and suggestions. Thank you!
 

Pop Golden

Pop
Corporate Member
Inside pipe wire or anything else makes for clogs. In small shops like most of us have a PVC pipe will not provide the static needed to cause a fire or explosion. There is a guy at MIT that wrote a paper on the subject. It's on line if you look it up. The ground you need is from DC to machine to reduce those annoying little shocks at the machine. Just a wire (NOT in the pipe) from each machine to the DC.

Pop
 

Bas

Recovering tool addict
Bas
Corporate Member
I'm no expert, but your layout looks absolutely textbook. Nice straight run into the dust collector itself, 8" main trunk, no turns in the main trunk, 6" pipe for the various branches, and big blast gates. The only thing you could consider to optimize the airflow is by installing some blast gates at the main branches (in addition to each individual drop) so you can close off whole sections. But, give the size of the shop and raw power available, I don't think that's going to matter very much.

Putting the DC in a closet will help with noise, although you'll need a lot of mass to overcome the low rumbling. And you'll need to balance making it soundproof with the need for venting, you won't want your closet to add resistance to the setup.

I do recommend tightly securing tape measures, push sticks, small children etc. as they are likely to be sucked into the system :)

Great rendering BTW, looks like an awesome shop!
 

Rushton

Rush
Senior User
Thanks for your very kind comments and suggestions, Bas. We will definitely keep an eye on those small children. ;)

I think you may be correct that the overall power of this system in such a fairly small shop makes shutting off the unused trunk runs not too critical. I'm open to other people's thoughts about this, however. My main reservation is access. These horizontal branch lines will be 8' up in the air. We'd need a DIY double pull cord configured blast gate for manual operation or we'd need remote actuated gates.

When I post some drawings of my plans for the sound insulation closet, I hope you'll comment on that. I'm planning on adding mass in addition to insulation. I also plan a baffled wall that will allow for 2x the cross section area of the 8" pipe while forcing the exhaust airflow to make a couple of turns to exit. Big concern is not to constrict the airflow.
 

rcarmac

Robert
Corporate Member
Just curious, in a shared space do you see 2 people using tools at the same time. Just wondering if you would notice a suction drop if 2 gates or more were opened at the same time with those big 6" and 8" duct runs.
 

Rushton

Rush
Senior User
We fairly routinely had a couple people working in the shop in pre-pandemic days. I'm anticipating we will once again as we work our way out of this need for social isolation. So, I'm laying out the duct work to allow for two machines to be operated simultaneously as long as each machine is on a separate 6" branch leading into the 8" trunk. The CVMAX cyclone is designed for this use and I would not expect to see any material airflow drop.

If two machines were being operated on the same 6" branch, then I would expect to see airflow drop in that case. This is why the bandsaw, the table saw, the jointer, and the lathe each have dedicated 6" branches connecting independently to the 8" main trunk.

Interestingly to me, Clear Vue offers the 16" impeller from the CVMAX as an optional upgrade to their model CV1800 cyclone. (That's what I used in my home shop before.) But since the CV1800 has "just" a 6" input, it is rated by Clear Vue for single machine at a time use only. Perfect for a one person shop; not so for a shared space like this. The key is that 8" input in the CVMAX; it allows for so much great air flow.

We'll have to educate users that they cannot operate simultaneously two machines that share a single 6" branch back to the main trunk. An example would be the router table and the miter saw. Both share a 6" branch and so should not be operated together. As we finalize the layout design, I want to get further input from our users about which machines are most likely to be used simultaneously and adjust accordingly.
 
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tvrgeek

Scott
User
Thanks for your very kind comments and suggestions, Bas. We will definitely keep an eye on those small children. ;)

I think you may be correct that the overall power of this system in such a fairly small shop makes shutting off the unused trunk runs not too critical. I'm open to other people's thoughts about this, however. My main reservation is access. These horizontal branch lines will be 8' up in the air. We'd need a DIY double pull cord configured blast gate for manual operation or we'd need remote actuated gates.

When I post some drawings of my plans for the sound insulation closet, I hope you'll comment on that. I'm planning on adding mass in addition to insulation. I also plan a baffled wall that will allow for 2x the cross section area of the 8" pipe while forcing the exhaust airflow to make a couple of turns to exit. Big concern is not to constrict the airflow.
Might GOOGLE some on sound management. Understand the differences between absorption. blocking or frequency shifting. A lot of what is "conventional" or "intuitive" is incorrect. It is not rocket science and is well understood. Owens Corning is your friend. As this is a shared space, pay attention to fire code on sound materials. Might see how vibration is transmitted from the DC to the floor and ductwork.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
The layout looks good. I can't tell their height, but make sure blast gates are positioned where people can easily reach and will use them.

With a 9.5' ceiling, one option is to raise the floor 10" - 12" - screw ply, Advantech, etc. down to pillars and beams, then run the duct (and electrical for TSbelow the floor. That almost eliminates vertical drops except one up to the cyclone.

Unless you have really bad ducting with leaks everywhere, there is absolutely no need to add blast gates to close off trunks or drops. You just need them at each machine. With the machine blast gates closed, no air flows through the drop or trunk therefore there is no turbulence generated and no static pressure issue. Bill Pentz incorrectly left the recommendation to put blast gates on trunks/mains on his website, but he is WRONG! Since you are using PVC DO NOT glue or solvent weld it together- friction fit only. Use a single screw to keep it from separating if needed on vertical fittings and joints. Then after everything is fully assembled seal the fittings and joints FROM THE OUTSIDE ONLY with a TINY bead of silicone (not latex or hybrid) caulk. Remember the system is under negative pressure so the caulk will be pulled tight. If you use silicone on the outside you can easily disassemble parts and easily rub the silicone off with a finger, when it is time to reconfigure your duct- you will reconfigure sooner or later.

PVC, as you said wouldn't generate enough spark potential to start a duct fire. It is not a conductor so will accumulate static just inches from any grounding wire or foil so that is of marginal effectiveness. Often, once the duct is seasoned it stops generating static. Also, with the humidity in AL it may not be a problem anyway. If it is, just wrap grounded foil, screen, mesh, etc. in the areas most likely to be touched.

Make sure your sound isolation closet is ventilated so the motor will not overheat and it won't block air flowing from the filters- the closet is part of the "DC system." Any resistance anywhere in the system will reduce the efficiency of the system. Any chance of putting the closet outside or in the storage room? That would be my preference.
 

Rushton

Rush
Senior User
Might GOOGLE some on sound management...
Good thoughts, thanks! I'm thinking in general terms about double layer sheetrock, Owens Corning Pure Safety fiberglass batts (NRC of 1.20), and baffle exhaust with large enough cross-section not to restrict airflow so the closet does not pressurize and the cyclone is not constricted. I have to check into wall mounting vs stand mounting the cyclone. That will depend on the construction of that back wall.
 

Rushton

Rush
Senior User
Alan, thank you for your comprehensive comments! You helped me tremendously two years ago when I was first trying to figure all of this our for my home basement shop.

I'd love to run all of this under a floor, but I don't think we have the funding (or permission) for these kinds of modifications to this space.

With your reinforcement about blast gates at the machines only, I'm set to move ahead with that plan. I thought I'd recalled you making this comment elsewhere, but hadn't been able to find that discussion.

Thank you, also, for the pure silicone caulk recommendation. I had planned to use either aluminum faced HVAC tape or silicone tape. The silicone caulk sounds like a simpler and cheaper solution.

I'm still contemplating whether to run the aluminum duct tape along the length of the PVC pipes and connections (inside and outside runs, pressed tightly to the surface and overlapped). I did this in my last shop and it was a time consuming process. On the other hand, I never got a surprise static discharge from touching one of my machines. I don't like the thought of running copper wire everywhere. The decision regarding taping is "do it now, or never again".

I plan to allow very liberal ventilation to the closet. We don't have an option to put the closet outside. We may have an option to place it in the storage room but I haven't played around with how the ducts would run if we could do this. The storage room will have an open 4' passage way through the wall into the shop, so there will not be a door to provide sound insulation if we were to move it in there. At least this is what I've been told. I'll check further on this.
 

Alan in Little Washington

Alan Schaffter
Corporate Member
You should never get a shock, electrical or static, from a machine (unless enclosed in a plastic cabinet.) The structure and cabinet for most machines is metal, metal conducts, so the structure, either through direct contact or grounding strap should be grounded through the power cord. Don't run anything, metalic tape or wire, inside the duct!
 

McRabbet

Rob
Corporate Member
Rush,

I concur with Alan's (and others) comments on your plan and agree with Alan on the use of clear silicone caulk on the PVC joint exteriors to thwart any minor leakage. If you insist on stemming static electricity buildup, you can use HVAC metal tape and only on the outside and then where a person might get zapped, wind a piece of bare copper around the duct and attached it to the metallic body of the machine. I also agree that you do not need overhead blast gates on 6" branches that feed multiple machines.

And your layout will allow multiple machines to operate simultaneously with a CVMax. Back in 2007, I visited the original owner of ClearVue Cyclones (Ed Morgano) at their shop in Pickens, SC where they were building the cyclones. He and his son Matt designed and built two CNC machines to cut out the blower parts and the original model of the MiniCV06 cyclone from 3/4" MDF. They had a CVMax with a very similar overhead layout to yours with an 8" main trunk and 6" branches serving multiple machines, including the CNC's. With both machines running and their blast gates open, Ed demonstrated the fate of a 25' Stanley tape measure held in the palm of his hand moved into the dust shroud around one of the CNC's router base -- the tape was immediately sucked up about 6-1/2 feet into the 8" main and tumbled into the CVMax's dust bin in less than 3 seconds. Lots of airflow and suction indeed!
 

Bill Clemmons

Bill
Corporate Member
Some observations, and apologies if you addressed these in your earlier comments, or if some of the responders have already covered them.
1). Floor sweeps. If you don't already have them in the plan, I would include at least two, one on each side of the shop.
2). Emptying the dust barrel. It appears the DC is at the far end of the shop from the wide door. Will you be able to wheel the drum out through the side door to empty it? Kind of a pain if you have to go all the way through the shop w/ a full barrel to empty it.
3). Is there any chance you could put the DC in a small room on the other side of that wall (the outside)? That would greatly reduce noise and make it easier to empty.
4). Try to find a way to bypass the DC filter and vent directly to the outside. Cleaning those filters is a real PITA.
5). At the miter saw will you be sucking the dust 'up' into the duct? If so, you may want to rethink that. I had mine that way and it never worked very will. I just completed a reroute of that part of my system to pick it up from the bottom of the compartment behind the saw, and it works much better.
 

Rushton

Rush
Senior User
Alan, I greatly respect your knowledge and recommendations. And, I similarly respect what Bill Pentz says and contributes. In that regard, I've noted Bill's story from Brent Dugan, a Maintenance Supervisor/Plant Engineer, about solving a serious PVC pipe static issue in his plant where polypropylene fiber is processed and transported via PVC pipe. He applied the aluminum foil tape to the ducting after being unsuccessful in every other attempt at a solution - and it worked. I assume you've seen Bill's recitation of this story and Bill's commitment to applying the aluminum tape treatment to his PVC ducts. The link to this story and process is here:


Bill comments align with yours in several respects. He says leading up to sharing this story, "As I said before most grounding approaches do not work well at all and most attempts to put metal inside our ducts leads to plugged pipes. Here is a workable solution shared by one of the many contributors to this site."

So, possibly this is all anecdotal and it was a solution to a severe static problem that we're not likely to experience in our wood working shops.
 

Rushton

Rush
Senior User
Rob (McRabbet), thanks for your input. I think between Alan's very firm advocacy and your gentle concurrence, we may simply bypass any static "treatment" of the PVC pipe until some issue shows itself. As Alan points out, this is Alabama - it stays somewhat moist here most of the year.

Bill, I very much appreciate you offering your comments. I've thought of adding dust sweeps and will keep these in mind as I work through final equipment placement and where we might have drops that can be adapted to this. I don't think we'll be trying to bypass the filters, that would send too much AC into the void at too high a cost. Great suggestion about the miter saw drop; I'll look into that but I note that Jay Bates is not having a problem with collection in his new shop (link here) using a similar setup, and he previously had bottom collection set up in his old shop.
 
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Wiley's Woodworks

Wiley
Corporate Member
We fairly routinely had a couple people working in the shop in pre-pandemic days. I'm anticipating we will once again as we work our way out of this need for social isolation. So, I'm laying out the duct work to allow for two machines to be operated simultaneously as long as each machine is on a separate 6" branch leading into the 8" trunk. The CVMAX cyclone is designed for this use and I would not expect to see any material airflow drop.

If two machines were being operated on the same 6" branch, then I would expect to see airflow drop in that case. This is why the bandsaw, the table saw, the jointer, and the lathe each have dedicated 6" branches connecting independently to the 8" main trunk.

Interestingly to me, Clear Vue offers the 16" impeller from the CVMAX as an optional upgrade to their model CV1800 cyclone. (That's what I used in my home shop before.) But since the CV1800 has "just" a 6" input, it is rated by Clear Vue for single machine at a time use only. Perfect for a one person shop; not so for a shared space like this. The key is that 8" input in the CVMAX; it allows for so much great air flow.

We'll have to educate users that they cannot operate simultaneously two machines that share a single 6" branch back to the main trunk. An example would be the router table and the miter saw. Both share a 6" branch and so should not be operated together. As we finalize the layout design, I want to get further input from our users about which machines are most likely to be used simultaneously and adjust accordingly.
After two years in a shared shop at Haywood Community College, I will vouch that there is no likelihood in regards to which machines are likely to be used simultaneously. Each woodworker is working on his own project and schedule, so there is no connection between projects. Lay out your machine locations as if only one person is using the shop at a time. You probably already have a common sense understanding of the flow from rough board to end-of-milling working pieces. Give thought to how we move around individual machines as we use them and allow for room to move without bumping into a fellow woodworker who is stationary at another tool.
 

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