Dust Collector CFM

KnuckleDownKnives

KnuckleDownKnives

Time to make the doughnuts..
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Feb 12, 2015
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Hi all. So I was just out taking in my afternoon smoke break and decided to check out the scrap dumpster at work and low and behold a squirrel cage fan is up in it. Talked to my bud the maintenance manager and inquired if anything was wrong with it. He said nothing other than he was tired of looking at it and being in his way all the time and if I wanted it to go ahead and get it, as he knows I like to build stuff.

Anyway I believe from the number on it it is capable of 3000 CFM

I looks like it's from a train twe090a300ca 7 1/2 - 20 ton unit.

Do you think this is way to big for a collection system?

Part #: A15-15AC 1.0 1SS






 
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Well it's a good day in Pleasanthill. Just got a 115/230v 1/2hp motor for free as well. It's a jet pump duty motor but I think it'll suffice. It was free anyway. And has a standard 5/8" Keyes shaft.



 
Hey man... been there... done that.

http://www.bladeforums.com/forums/s...-made-a-dust-evacuation-system-for-my-grinder

Works well enough. But CFM isn't the importance factor for a STEEL dust collector... velocity is. I had to step mine down quite a bit to make it feasible as a collector. It will work for fine dust but doesn't have the velocity for the heavy stuff. Mine served me well for 2yrs until I built a new shop and invested in a new unit.
 
Thanks for the input. Stepping up velocity shouldn't be too difficult if I design it from the beginning. It pulls air from both sides so I'm thinking of making a split system. The blowers has two cone shapes plates in the center of the fan. I'm thinking of making duct work that incorporates a divider shroud in the center of the outlet to divide the two sides so I can use one side for metal working tools ant the other for wood working tools. This is still a long way out but better planning I believe leads to better outcome. I just happened to come across these parts so who knows. I may just hook the blower and motor up and use it to help cool the shop the rest of the summer as I'm sure I'll get better air flow with this than the 3 box fans I'm currently using.
 
I am sorry to be the bearer of bad news but you will never get the velocity with that blower. I have spent countless hours with this rig.... consulted professional HVAC and industrial filtration technicians.... your system is limited, brother. Functional... but limited.
 
Rick's right, it's not the right type of fan. The squirrel cage fan is designed to move air efficiently, but not against much back pressure. It's designed for very large ducts with fairly low airspeeds. It takes 5000 feet per minute airflow to keep steel and abrasive dust moving reliably in a duct. At 3000 CFM the closest size would be 10" diameter. But if you hook up a cyclone or filter, or both to your fan you will have put enough back pressure on the fan that it won't be moving 3000 CFM anymore. Even just reducing the intake on the fan to 10" will cut the airflow dramatically. If you reduce the duct size to increase velocity you put more back pressure of the fan and airflow will drop even more. It's a vicious cycle you won't win. You need a fan designed for the purpose, radial fin, airfoil, caged impeller, etc.

What could you do with your fan?

Put it in a box with filters on the intakes and make your own version of the dust collectors sold to hang from the shop ceiling and clean the air. But make sure to use HEPA filters, otherwise you are just stirring around the smaller, more dangerous particles.

You could make a downdraft table for sanding wood, most of the commercial ones use crappy filters so if you do this add a HEPA stage or vent to outdoors

Or just use it to cool the shop.
 
Okay, I'm going to leave the horse dead you've already killed and proceed to not kick it... Looks like I have a good replacement for the three box fans I have that keep a cross breeze through my shop. Maybe build a small stand on casters so I can move it around. I have a feeling this will work for that much better the the 3 fans I'm using. At least it was all free stuff and no money wasted.

Thanks for the input guys.

I'm going to post these images so anyone that happens across this thread can see the difference in fan blades.


This is what I have that won't work.



This is the type in a typical dust collector that would work.

 
What it would do is make a heck of a fan for ventilation, just moving air into and out of your shop.
 
That's what it's going to do as of now.

kuraki said:
What it would do is make a heck of a fan for ventilation, just moving air into and out of your shop.
Click to expand...


Just went and talked to our maintenance manager to inquire what the drive pulley size was on the motor and he just gave me the motor and pulley that went with it. So looks like all I got to do now is make a stand for it and wire it up. Looks like it may be a little cooler in the shop this weekend. That will be highly welcomed.
 
Bill Pentz's website is the best dust collection resource out there. Unfortunately he does tend to repeat himself. It's as if he worries that folks will only read a topic or 2 so he puts the same information in a lot of places. Hang in there and once you get a feel for what you can skim over because you've read it before, the website won't seem so overwhelming. That said, he's mostly writing about collecting wood dust. But the principles of air movement, filtration, etc. are mostly the same for metal, at a slightly higher air flow rate.

The couple paragraphs about metal dust are at the bottom of the FAQ page. Bill's mostly right, although I would not want to lift a 55 gallon drum full of metal dust. But even most more expensive dust collectors designed for metal dust have very poor filters that just push the fine dust through, and what he says about modifying your machines with bigger hoods...I spent today starting on a hood to connect the 6X48 belt grinder to a 6" duct

I'm currently waiting on some parts for an experiment with a 2 Hp cyclone I'm going to try as a collector on the 6X48 and 2X72 belt grinders. I"ll post what happens.
 
Folks, related to a previous thread of mine, I would like to throw out a question here, I have several 'point of' dust collection vacuums at my highest dust producing machines--these are high end shop vacs--Festool and Fein with cyclone CV-06's on the front end. I still end up with a large amount of dust that settles on everything in the shop, I have a Jet air filter running that is mounted on the ceiling of the shop--which is actually fairly low at 9 feet or so. I'm looking for advice on what to buy that would spit the dust outside, I have a couple of half glass doors and a window in the shop that I can put an exhaust into.

Any help/advice is appreciated.
 
Fish... it is difficult to troubleshoot your dust problem without seeing the machines and systems. Perhaps make a new thread specific to your problem, complete with pics. I suspect that either your current dust collection isn't set up optimally or you have another dust source not fully dealt with. Do you sweep your shop? Are the exhaust ports on your shop-vacs controlled or vented outside? Are you diligent about cleanliness?... come on... fess up, we know the truth! lol:p
 
"Spitting dust outside" is not an economical method. Thats the short of the theory. The amount of lift needed, along with the detailed duct design to accomplish it, would make this cost prohibitive for the hobbyist or semi-pro.
 
ron_m80 said:
"Spitting dust outside" is not an economical method. Thats the short of the theory. The amount of lift needed, along with the detailed duct design to accomplish it, would make this cost prohibitive for the hobbyist or semi-pro.
Click to expand...

Not true... it depends on what type of dust you are targeting. In my shop the stuff that hits the bucket and floor is not the issue. I want to eliminate the fine particulates that get whipped around the belt and hang in the air. In my experience, that is quite achievable. My last shop was 10' x 20' and I managed to keep it free of dust when I played by the "rules".

- Avoid sweeping whenever possible. Use a shop vac.
- Exhaust your shop vac outside... or at least, control the direction it blows.
- Devise a system that allows the outside air in, without completely cooling down your shop in the winter. I constructed a semi-closed loop in my grinder shroud that virtually eliminated any issue.
- Make sure ALL of your ducts and hoses are sealed tight. Any leaks will spit out dust like a sprinkler.
- Do Not allow dust to accumulate on your floor. Even opening a door can kick up debris... you need to stay on top of it.
 
In almost every situation I have encountered with a similar dust problem to Fish's the source of the fine dust was the existing dust collection system. Shop vacs spit out a lot of what they suck in. Cyclones and the large bag-vac systems will often exhaust fine dust.

The solution is to exhaust as many or all of the existing collector systems directly outside. Remove all noise suppressors and secondary HEPA and fine particle filters. The main filter usually needs only filter larger stuff from the system if the air isn't being returned to the shop. Many folks use just a vac blower and duct work with no cyclone or filters at all. The less resistance in the path of the system the higher the velocity, and the more dust is expelled.

The hanging box collector is OK to leave as-is, but needs the filter vacuumed regularly.
 
I claim the title of the shop with the most dust, so I can shed a little light on the situation. I have removed over 500lbs. of dust this year, feel free to tell me if you have removed more dust. Literally, about 10 buckets of brick dust. I use a small shop-vac for removal and it works quite well.

First, my vac is a WD1450. It's the quietest shop vac you've ever used and only $99. I use it with the yellow Rigid brand bags. Yes, it makes a difference. The generic bags tear easily. I also use a double cyclone system on two different buckets. Three buckets doesn't make a big difference, two is the sweet spot.

Second, I have a 20" box fan with 3 cheap air filters on it to filter the air, works really well for airborne particle that linger.

Now, the part that helps the most with the dust in the shop: how you enclose the dust at the point of creation is the most important part. This can get pretty elaborate. I built quite the box around a drill press setup to capture the dust, including 2 vacs to gather dust above and below the bricks being drilled.
 
Atlas Knife Company said:
Now, the part that helps the most with the dust in the shop: how you enclose the dust at the point of creation is the most important part. This can get pretty elaborate. I built quite the box around a drill press setup to capture the dust, including 2 vacs to gather dust above and below the bricks being drilled.
Click to expand...
This can't be stressed enough. I was having issues with my grinder shroud. I finally resolved it with a 1.5" right angle lip at the opening. It formed a current that kept the dust in the shroud to be eventually drawn out. It made all the difference.
 
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