Dust Collector Question

[George Kretschmann]

I have a 2hp Jet DC 1200 cfm I want to take off the "Y" off of the impeller housing and go from the 2-4" pipe "Y" to a 6" adapter of some kind. What should I use there...to accomplish this? I plan to duct the shop with 6" drain ( thin wall pvc) throughout... any thoughts on this???:) .

[Thomas Prondzinski]

George
I used to have a dc-1200,just removed the y adapter and slide on a 6" hvac pipe.There's a collar under the y adapter.



Tom

[Anthony Anderson]

George, I removed the Y and installed a 6" elbow and ran the main trunk out of 6" with 4" branches. Seems to work well. Do your research, but don't over think it (like I usually do). Just do it. HTH, Bill

[George Kretschmann]

LOL...I usually overthink things to the point of no return. I thought I was the only one who does that.:D Thanks for the info, I figured it would be a big production, sounds easy enough. I should of run 6" pipe from the start of the project but did not know any better instead I did 4" all the way. I figure I will see a diffrence in performance, I think the DC is not doing what it should running 4" all the way. thx gk

[Jeffrey Makiel]

George,
I don't recommend putting a 6" 90 degree elbow connected directly to the inlet. This will significantly hurt overall fan performance. Try to get some straight duct, about 30" long, between the elbow and the fan's inlet.

Also, using 6" duct will make a world of difference! Enjoy!
-Jeff :)

[George Kretschmann]

That's a 10-4 Jeffrey.

[Anthony Anderson]

Jeffrey, I agree with you on this point, but as I have a small shop in the basement, where every inch counts, I just could not do it. However the way I have it set up, it still pulls excellent. Been set up this way 4 years now and no problems with clogs or inefficiency. I have the router table about 17' away from the DC (shop is long and narrow) and it pulls everything from the router. Regards, Bill



George,
I don't recommend putting a 6" 90 degree elbow connected directly to the inlet. This will significantly hurt overall fan performance. Try to get some straight duct, about 30" long, between the elbow and the fan's inlet.

Also, using 6" duct will make a world of difference! Enjoy!
-Jeff :)

[Bob Dodge]

Hi George,

If your Jet DC-1200 is the version which has a 12" impeller, and twin 1 micron filters, with a 6" blower outlet, you'll get 1025 cfm at roughly 4" sp., using a 10 foot long, 6" diameter pipe. You should easily be able to have a full-sized 6" drop to at least one of your machines, if the drop is efficiently designed. You have to allow for a pressure-drop of roughly 1" sp at the filter as it loads, which leaves you a balance of 3" sp loss for the ducting.

Assuming you'd be looking for 800 cfm at the table-saw, your 3" sp will be partially attributed to entry-loss. That should be in the vacinity of 1.25"sp. This would leave a balance of 1.75"sp for "length loss", which is the friction loss along the interior of the pipe.

With a smooth-walled pipe such as PVC, that 1.75"sp translates to roughly 47 feet of straight-pipe.

Remember, of that 47 foot length, each elbow along that run has the same resistance as 12 feet of straight-pipe. 3 x 90 degree elbows will have the same resistance as 36 feet of straight-pipe. That 47 foot run, includes the elbow values. With three 90's, you could use a maximum of 11 feet of straight-pipe, plus those three elbows.

Those resistance values were calculated at 800 cfm/4076 fpm. We've also allowed for a 1" pressure drop at the filters. You can most certainly use a bit more pipe, but the cfm will be reduced accordingly. You may get something like 700-725 cfm total at the saw with dirty filters, and 800-825 cfm with a clean filter.

If you place your dc close to the saw, and keep the duct-run horizontal (blower-inlet height) you can expect over 900 cfm at the saw.

Bob

[George Kretschmann]

Bob, with all of that said (alot of good info) I usually use 1 machine at a time. I planned to drop 6" to all machines that would except or could convert to 6". Do I need a bigger DC?? I only have a 24 by 24 shop but I want a good DC system to get the dust out. I currently have the DC outside the shop for noise considerations and I do not want to recirculate the air. Sounds like I need a 3-5 HP DC machine to do a good job. Thanks for the techinical info, didn't know that. gk:)

[Bob Dodge]

Hi George,

If you're planning on using all 6" drops to your machines, then I would indeed recommend that you go with a more powerful dc, especially if some of those runs have four or more 90 degree elbows and lengthy duct-runs. I'd probably take a close look at a 13.5- 14" impeller dc such as the Clear-Vue, Oneida or Grizzly cyclones. At that price-range, you'll get very good performance.

A 3hp single-stage with 13.5" impeller would have stronger suction, but those tend to be much too large for the average home-shop. Often well over 10 feet tall, with triple-phase electricals. Overkill for most small shops. These units pull around 1400 cfm at 8.5" sp. through a 7" pipe,

If you're going to go with all 6" pipe-drops, you only need to identify the load at the "worst-case scenario" branch. Calculate your losses based on 4000 fpm through the verticals, and your "equivalent length" losses for each elbow along the run.(12 ft/elbow). You'll want a minimum of 4000 fpm through those verticals, so use a value of .036" - .040"sp per foot. With 40 feet of straight-pipe, and five 90 degree elbows, your static-pressure losses will be roughly equivalent to 100 feet of straight-pipe, or 3.6"- 4" sp, plus the hood-entry loss. Assuming a hood loss of 1.25" sp, you're looking for a dc that can pull 785 cfm/4000 fpm "at" 5.25"sp. Don't forget to allow roughly 1" sp for filter pressure drop. Using the system performance curve for a particular dc, you'd want roughly 785 cfm "at" 6.25" sp.(clean filter) or better.

Personally, I don't think you require 6" drops to all your machines, but that's your call. If I were sizing a run for the shop you've described, I'd probably run a 7" main to at least the first drop (table-saw), with a 6" drop to that machine. From that point along the main, I'd go with a 6" main, and 5" drops. Plenty for most jointers/planers. With those three "majors" taken care of, that leaves the smaller machines, like your router-table, etc. It's up to you to decide if the 6" runs are worth it. You need a bigger dc, and more expense. You presently have a pretty decent dc, and with a well thought-out duct network, you may be very surprised at what you can achieve.

Bob

[George Kretschmann]

Bob,
I believe I will go with the 7" to a 6" or a 6" to a 5" or a 4" pipe. As you said put the more demanding machines first. Currently I have to go 24' of 4" pipe before I get to the first drop, I knew better than this before I did it but had to because of the layout of everything. It will be better this time for sure.Thanks for this valueable info. gk:)

[Anthony Anderson]

George, there you go overthinking it again. Just hook up the DC on a 6" trunk and branch off with 4 or 5". It will work fine. You are only using one machine at a time. If you spend all of this time reading about drop and all of the other stuff (it is good info and I am sure these guys are very knowlegeable), you could refab your system from scratch five times. I have all of my runs overhead, nothing on the floor, or low along the wall. It works great, and does not lack sucking power. Just put it together, and use it, and be happy:D. Regards, Bill

[George Kretschmann]

George, there you go overthinking it again. Just hook up the DC on a 6" trunk and branch off with 4 or 5". It will work fine. You are only using one machine at a time. If you spend all of this time reading about drop and all of the other stuff (it is good info and I am sure these guys are very knowlegeable), you could refab your system from scratch five times. I have all of my runs overhead, nothing on the floor, or low along the wall. It works great, and does not lack sucking power. Just put it together, and use it, and be happy:D. Regards, Bill

Yep...I did it on the first post here.....what a struggle i have with this "overthinking". I guess I like all of the knowledge and weigh in all of the facts and opinions. My wife even said are you still posting about the DC system, move on to something else:( . Thanks for reeling me back in Anthony.:D

[Dale Thompson]

George,
If you are only using your collector for one machine at a time, why would you want to use a 6" duct? 4" should be MORE than sufficient. The REAL trick is to avoid "drastic" size changes (i.e. 6" to 2"). Even if your system is fully controlled by gates, this drop will give you virtually NO collection capability. :( A dust collector impellor is like a window fan. If the resistance is too great, the air will simply bypass the impeller. Another hint is to minimize the use of "flexible" hose. That stuff has about fifty times the resistance of plain old PVC. ;) :confused:

One last thought, if your machine has a dust extractor in the area of 1 1/2" to 3", you are much better off with a shop vac. A shop vac operates on a TOTALLY different principle than does a DC! :confused: :)

Now I think that I am confused? :confused: :)

Dale T.

[Rob Wilson]

Bob mentions doing a horizontal run from the DC inlet. On the Delta 50-760 this would require a 90 right at the inlet.

Jeffery made the point not to put the 90 right at the inlet (I'm guessing that this is to reduce turbulance going into the fan) but to have 30" or so from the 90 to the inlet. This means drops of 30" or so to each machine for an additional 90 and ~60" of duct.

So we seem to have to mutually exclusive setups - more turbulance into the fan or more duct/bends. Any ideas on which will give better performance?

[George Kretschmann]

George,
If you are only using your collector for one machine at a time, why would you want to use a 6" duct? 4" should be MORE than sufficient. The REAL trick is to avoid "drastic" size changes (i.e. 6" to 2"). Even if your system is fully controlled by gates, this drop will give you virtually NO collection capability. :( A dust collector impellor is like a window fan. If the resistance is too great, the air will simply bypass the impeller. Another hint is to minimize the use of "flexible" hose. That stuff has about fifty times the resistance of plain old PVC. ;) :confused:

One last thought, if your machine has a dust extractor in the area of 1 1/2" to 3", you are much better off with a shop vac. A shop vac operates on a TOTALLY different principle than does a DC! :confused: :)

Now I think that I am confused? :confused: :)

Dale T.

I agree Dale, a Shop Vac is a totally different animal from a DC. The Dc pulls better on 6" than a shop vac would. I ran some 2" pvc around my shop and hooked up my chop saw and router table then plummed it into the 4"...did not work good at all...matter of fact I would call it a lesson learned. :o



Rob Wilson...I don't think I can't afford a commercial DC system in my 24 by 24 shop. But with what I have, I can maximize the DC as much as possible as far a efficiencies go. My current set up is restricted as far as pipe length, and total distance from machine. I can improve this greatly with the info I have received here. I will have to use some flex right off of the empeller housing but will keep all of that short at the machines.:)

[Bob Dodge]

Hi George,

If you plan on staying with your Jet DC-1200 for the time being, there are plenty of ways to coax extra performance from your dc and pipe runs. The info I provided earlier, is pretty basic resistance calculation information. There's a lot of "wiggle room" for creative design.

Obviously, you want to keep the use of flex pipe to an absolute minimum. Depending on diameter and surface texture, flex can have three times the resistance of smooth-walled pipe, especially as pipe diameter reduces.

You also want to use nice long-radius elbows wherever possible. 1.5 x diameter, is the minimum you should consider.

Avoid using an elbow directly at the blower inlet. Use a short length of straight-pipe, and THEN attach any elbows you may need. This will create a nice laminar flow into the impeller. Otherwise, the impeller is dealing with turbulence created by an effect known as "vena contracta". A 2'- 2 1/2' length of straight-pipe, should minimize or eliminate that effect.

Keeping your duct runs at blower inlet height, eliminates ceiling drops to your machines. This can result in a MAJOR boost in air-flow. You'd be eliminating at least three 90 degree bends, plus the riser and drop pipes. That can easily reduce the duct run by as much as 50 feet, resistancewise. Remember, each elbow acts like 12 feet of straight-pipe, in terms of resistance.

Preseparators, can also be used. A presep, will allow your filters to stay cleaner longer, increasing suction. Mind you, they can and will add their own resistance, so they have to be properly designed.

Placement of the dc closest to your largest machines, will effectively shorten your duct-runs and increase cfm.

The use of over-sized filters can greatly reduce pressure-drop as the filter loads. It's also a way of dramatically improving small-particle filtration.

Dc's are generally assembled in a traditional manner, but there is absolutely no reason why you cant remove the blower/motor assembly from the "cart", and place your blower close to the machines being served. This could be handy for those who do not have room for a dc, close to those machines. You could simply run a length of straight-pipe from the blower outlet, to a remote waste collection point.

You can also totally eliminate the bag-tree that comes with your dc, and make a simple plenum which sits on a pair of drums. That plenum need only be large enough to cover the drum(s). Mount your filters to the top of that plenum, and fasten the blower directly to the side of that plenum.

Yet another way to reduce resistance where ceiling drops are preferred, would be to mount the blower at the ceiling, and venting downward into a waste collection container. This would allow you to use oversized pipe at the blower outlet. You'd be eliminating several elbows, and reducing blower outlet resistance. The waste container, can be as large as you like, with your filters mounted to the top of that unit. The possibilities are endless.

Bob