shop made air filter

[Mike Evertsen]

I almost have a air filter finished I built it from squrril cage and 3/4" plywood it will roll around the shop (to heavy for me to lift it up the the rafters) so it draws the air in from the top and blows it out the bottom,,
now for my question how much suction am I suppose to feel,,,it pulls the filter down but I don't feel much suction is this ok?????,,,,

[Terre Hooks]

"How much suction should I feel" is kinda hard to answer. If this fan is in decent shape, you should be able to look on the nameplate and see what the maximum amp draw is, then put a clamp-on ampmeter on it and see what it is drawing. The more amps, the harder the fan is working, usually the less air being circulated.

These HVAC squirrel cage fans work best with the least amount of restriction. Hopefully this air filter/work bench type box is perforated enough to allow good return (suction) and the supply (exhaust) is as unrestricted as you can get.

Hope this helps.

Throw some dust up in the air and see if it pulls it out.

[Wes Bischel]

Mike,

I did what Terry suggested. I used some fine dust from a sander, blew it into the air at different parts of the shop to see how well it moved. Good enough for who it's for in my case.

I used an old exhaust fan - the kind with the big round chrome grill found in 50's era kitchens. (taken out of my kitchen) It does a nice job of clearing the air. It doesn't preclude a dust mask, but it cuts down on the clean-up.

You may want to mock up the motor and try it before final mounting.

Wes

[Dennis Peacock]

Mike,

I bought a used squirrel cage blower and new Baldor 3/4 HP motor already mounted on it from a HVAC shop for $25 a few years back. I used 3/4" plywood to make a cabinet for it and use 2 filters 20 by 20 for its filtration. Air flow in tremendous with this thing and I can filter 1200 sq ft of my shop in no time flat. So far $50 I got me one really nice working air filtration setup. It ain't the prettiest thing in the world, but it really works well. You can really feel the air moving in front of the filters and the exhaust is enough to keep a kids kickball floating.

[Bart Leetch]

This is my dust filter system.
The dust filter has a 3 speed squirrel cage fan & the 3 micron bag filter inside system from Grizzly & a pleated filter in the front. I put this up on the ceiling by myself. I had it on a board on top of my table saw & blocked up my roll around floor jack & slid the filter system on top of the jack & jacked it up against the ceiling. Ain't nothin you can't do if you think about it awhile.

[Jim Becker]

The more amps, the harder the fan is working, usually the less air being circulated.

I could be wrong, but I believe the opposite is true...the fan is working most efficiently (and moving the most air) right at the point that it's drawing its rated amperage. That was how the various articles about tuning up cyclone blowers and adjusting the neutral vanes was accomplished.

[David LaRue]

I almost have a air filter finished I built it from squrril cage and 3/4" plywood it will roll around the shop (to heavy for me to lift it up the the rafters) so it draws the air in from the top and blows it out the bottom,,
now for my question how much suction am I suppose to feel,,,it pulls the filter down but I don't feel much suction is this ok?????,,,,

I had my blower set up on the floor for a while. I would recommend putting up on the rafters, it will work a lot better. I used a couple of strap pullers to hoist it into position. If you can suspend it from the rafters with chain, the job will go much easier. I have mine mounted over the right side extension of my table saw.




Dave

[Bill Ryall]

I just completed mine & mounted it in the rafters above my sanding station. When I first constructed it, it pulled the filters in, but I could barely feel any air movement. After I installed it, I created a bunch of dust by using my sander with no other dust collection- throwing a bunch if dust into the air. I then turned on the filter, and watched the cloud migrate into the filters. Still need to wear a dust mask sometimes, but I have noticed the air cleans fairly quickly, and my sinuses no longer bother me after a long day in the shop. Added benefit- LOML no longer complains about me snoring... makes for more domestic harmony.

Bill R.

[Terre Hooks]

I could be wrong, but I believe the opposite is true...the fan is working most efficiently (and moving the most air) right at the point that it's drawing its rated amperage.

I don't believe the same holds true on a squirrel cage or belt driven low-speed fan. On an impeller type vacuum system, yes, you are correct about the maximum amps being drawn when there is no restriction. I have seen this in the field on large vacuum systems.

Most of these homebrewed air filtration systems are built with HVAC fans, so keeping an unsrestricted flow is the goal. Think about it-you always hear about "make sure your air filter is clean" on your forced-air HVAC system.

[Wes Bischel]

Mike,

If you do mount it, make sure it is in front, or to the side of where you are generating most of your dust. What you don't want is the unit pulling the dust past you - so you can breath it in. The unit should be pulling the dust away from your face. I placed mine over my dust collector in a corner. It is not ideal from a circulation stand point, but it isn't in a location where it will pull dust into me.

When I built my unit, I lucked out that Lowes was dumping their Delta filters - both pre and pleated. I picked up both for under $10. Just lucky though. There are times when I do appreciate corporate logic - but that's another thread. Good luck finishing it up.

Wes

[Noah Alkinburgh]

Mike,

If you do mount it, make sure it is in front, or to the side of where you are generating most of your dust. What you don't want is the unit pulling the dust past you - so you can breath it in. The unit should be pulling the dust away from your face. I placed mine over my dust collector in a corner. It is not ideal from a circulation stand point, but it isn't in a location where it will pull dust into me.

When I built my unit, I lucked out that Lowes was dumping their Delta filters - both pre and pleated. I picked up both for under $10. Just lucky though. There are times when I do appreciate corporate logic - but that's another thread. Good luck finishing it up.

Wes

Wes,

I am going to have to stop by sometime and take a look at that. Also, I want to check out Hollingers Sawmill in Columbia some Saturday when time allows maybe we could meet up a BK just off of Rt. 30 and go check it out.

Noah

[John Preston]

With all pumps, centrifugal fans, etc. the more amps you pull the more work you do.

If you have the exhaust or inlet completely blocked, you are only circulating the air, and you do no work, thus minimal amps. If you run the fan with no restrictions or housing you will probably burn it up because you will pull too many amps. You want to get the amps up to rated amps to get the most airflow and work out of your fan. Exactly like a dust collector. Same principle.

Or at least that's what they teach in the school I went to.