Tips For Central Dust Collection

If you're considering putting a central dust collection system into your shop, I'm gonna give you some tips here to keep in mind as you go that are gonna make things work a little better, work a little more efficiently so that when you've got a good dust collector pull an air, you're getting optimal performance at the tool. While I'm leaning on the dust collector here let's point this out right away. If you've got a big inlet on the dust collector maintain that large diameter for as much of the run as you possibly can, the larger that main trunk is the better off you're gonna be. Here's an example, if we take four inch pipe and compare it to five inch pipe going just one inch larger in diameter actually gives us about twice the air flow through that system. So you can imagine if I neck this down from eight to four the difference, the impedance I'm gonna be providing to the air flow. So again stay large as long as you possibly can, go small when you gotta do drops specifically to a tool. Now talking about drops to tools. That's where you're probably gonna start working with flex hose and like anything there's flex hose and there's flex hose. So in the perfect world what I'd like to see is a flex hose that's got metal coils on the outside of the pipe. In this case these are plastic so this is not my favorite. The benefit to medical metal coils on the outside is that I can ground those metal coils so that I'm gonna tap take static electricity off the system here. What happens is that of course is we're pulling chips and dust through the plastic, we're building up a static charge. If I've got metal coils on here I can ground those dissipate, the static. If you don't have metal coils you're gonna have to take a step to provide a ground in order to dissipate that static charge. What I do like about this pipe is the fact that when I open it up and I put my hand inside because the coils are on the outside of the plastic the inside of the flex pipe stays pretty smooth. So a test you wanna do when you're buying that pipe is open it up, run your hand inside there and see how smooth a wall we have. The smoother the wall the better collection we're gonna have. 'Cause again we're preventing, we wanna stop stuff from impeding airflow. If this is full of ridges that's gonna impede air flow, it's gonna mess with your efficiency. Now talking about flex pipe, we wanna limit it to use. Stay with solid pipe as long as you possibly can here's the number with that, if I take a four-foot length of flex, a four-foot length of solid pipe this is gonna have about three times the resistance to air flow that the solid pipe will have. So again imagine the drop we're getting an airflow, the loss of efficiency at the tool none of those are things that we want. So limit your use of flex pipe as much as you possibly can. Now let's start kinda low tech. One option you have is to go to the home center and get standard off-the-shelf HVAC products. This is a four inch pipe that when I close that is gonna look like this. This is fine for dust collection, a general rule of thumb is that pipe like this is generally recommended for systems using a two horsepower or less dust collector. And the reason for this is it's relatively thin wall. So usually HVAC pipe off the home center shelf is 24 gauge, 26 gauge, maybe 30 gauge. Remember that with gauge as the number gets bigger, the thing gets smaller. So 30 gauge wall thickness is less than 24 gauge. The problem we can run into with a large dust collector is that if it happens that the blast gets all end up closed in the system and we kick on the dust collector with a thin wall pipe, you can actually collapse the pipe and we don't want that to happen. So what do we do in that case? One option is what's called spiral pipe because of the way this has made one it's a thicker gauge, two with it's spiral nature virtually impossible to collapse this stuff. So with a larger system, yes it's more expensive but plastic is a good or spiral pipe is a good consideration. What about plastic? What about using PVC? So PVC isn't a bad option at all we can get it four inch, we can get it six inch. It can satisfy a lot of your dust collection needs what do we already know that we gotta take into account? What about this whole grounding thing? If you use plastic pipe you're gonna have to add grounding to it which is commonly done by just having a wire laying inside the pipe that's then subsequently grounded. That'll dissipate that static charge, that all works great. One of the things I wanna point out is not all PVC fittings lend themselves to dust collection. This is a tee fitting, so you might very well say, well okay I've got a four-inch pipe on the ceiling four inch drop. The problem with this is think of dust coming into the system like cars getting on the freeway, in this case the car is coming in and has to make a sharp turn that's not very efficient. In this case, the car is coming in on an ramp and can easily merge with the existing traffic. This is what we want, we want merge not a turn from a stop sign. So using some of these standard PVC fittings is gonna limit your efficiency because we don't have the gentle on-boarding that we get from dust collection fittings. If you do go with PVC, you don't have to worry about gluing everything together. You can simply screw it together, we have enough friction on those joints. You can screw it together, the benefit to that is if you ever do get a clog in the system all you have to do is take out the sheet metal screws, open it up, get the clog out, put it back in business again. Now let's go back and revisit our HVAC a little bit. You're probably gonna need elbows and I've got a PVC elbow here as well that's got the same problem these have, the problem being, this is too small a transition as a general rule of thumb you want the radius of this elbow to be twice the diameter of the pipe. So four inch pipe should have an eight inch radius this ain't gonna do it, but we can work around this by joining two elbows that have been formed at 45 degrees. So net net, we get a 90 degree transition but look at how much larger we've made the radius. So that's what we need to do in order to make sure that that air keeps moving and keeps moving efficiently. Now if you go this route, one of the things we don't have here is a good airtight system because by the nature of the way these babies work we spin them to adjust the angle. I would go back and caulk each of the seams after you've got them formed correctly to make sure that each of those seams is correctly seal. Now while we've got this in a 45 let's go back and look at our main inlet over here. 'Cause there's another consideration is look how low this is, there's a good chance that our dust collection pipe is gonna be up here. And it could be pretty natural than what you decided to do is while I'm gonna elbow out of this, not with a four I hope but with the correct diameter elbow, I'm gonna elbow out of this, I'm gonna go up, I'm gonna elbow to the ceiling, I'm gonna start to get to my tools. A much better move is a 45 out of this, a piece of pipe. Whereas my other 45? There it is. 45 out piece of pipe, 45 over to get to the horizontal. That's a smoother transition again it's gonna keep all your dust flowing moving better, give you a better efficiency in the system. Similarly then let's keep talking about our HVAC components, should we use this one or not? You already know the answer to this. Is this a right turn or a left turn, or is it a freeway entrance? So this is a handy tee from HVAC systems, but this isn't something we should use for dust collection again, we wanna provide that on-ramp type setup. When you're stepping down make sure that your fittings look something like this where they funneled down as opposed to having a distinct step. This is a much better transition and this is in this case from four to three we wanna have this angle transition in between not a sharp step, this is gonna work much better. With the HVAC components, like I said be sure that you caulk the seams on those elbows when you're done, you can use silicone caulk they do make specific duct work ceiling that's readily available from a home center so that you can make sure you're good and airtight on these parts. Keep those tips in mind so that once you've got a good dust collector in your shop, you're getting optimal performance out of it at the tools and making sure you're getting all the dust collection that you need and you should get based on the performance of the machine.