PMAC...(Poor Man's Air Cleaner)

[onedash]

Are you just using the fiberglass 99 cent filters? It looks like it. I don't think that is going to do a whole lot to keep you healthier. Those don't trap very small particles.(well not a high percentage of them) For my house I spend about $15X2 every two-3 months for the good pleated high efficiency filters. They work way better. As a matter of fact the grates that cover them both are usually covered in dust because they trap so much more than the cheap fiberglass ones. It probably reduces the airflow a little but so what. No idea how old the air handler is but Im guessing the size of the filters were not calculated using high efficiency ones.
As far as sawdust goes Its the dust you can't see that im sure is gonna hurt you and it will probably pass right through those. Especially without a lot of airflow since those rely mostly on static electricity to catch particles.
I also read in several places that the ion generators can be bad for you and do little to nothing to clean the air any better.

[LCHIEN]

Are you just using the fiberglass 99 cent filters? It looks like it. I don't think that is going to do a whole lot to keep you healthier. ...

SAlty did say he has two levels of filtration; I don't know if he bought for the second level the expensive furnace filters that trap the really fine particles. Should have.

I did notice on the Delta website that the individual filters are for sale. The 1 micron pleated filters can be had and they are a standard size (8" x 19"? comes to mind), easy to build a holder for and for the first stage you can use a standard furnace filter of the same size.

[LCHIEN]

Hi:

My shop is in my garage which is far from air tight.. Fresh air comes in under
the door and through a couple of other openings which aren't sealed tight.
Can someone tell me if an air cleaner (specifically the Delta at Lowes for $200) would do any good in this environment? I've been thinking about buying this model but I've also read in places that it's too small, especially for garage shops like mine.... any thoughts?

Steve

Since the air cleaner pulls air from the same room it puts it out, there is no net pressure build up that would either cause a lot of air to move in or out of the garage, any more than normal. I looked at the Delta site, the triangular delta unit is 450 CFM, that will be way more than goes in or out the leaky places in your garage, in my opinion.

As for being sufficient capacity, read my other post where I suggested that I recalled reading you should have sufficient CFMs for 6-8 air changes per hour.
With a 20'x20'x8' garage, then you get 8.5 changes per hour, that would be sufficient if you didn't count any open attic space over the rafters.

[Flatlander]

Here is a $130 option, and it has a remote:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91393

Or this $100 option that I got for $20 durring amazons' $80 coupon problems

http://www.amazon.com/gp/product/B00004T181/qid=1142625954/

[LCHIEN]

Here is a $130 option, and it has a remote:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91393

There's something wrong with the spec. It says 3 speeds, the top speed is 360 CFM, and it says it will change the air in a 20x20x8 room 15 times per hour. It takes 800 CFM to do that, its short by at least a factor of 2.

[JTimmons]

Okay, I got a question. I picked up a couple of box fans from HD on clearance last fall for $5 each. The specs say they have 2068 CFM on low, 2610 CFM on medium, and 3226 CFM on high. I have noticed while running these they like to suck up any of the Lowes and HD plastic bags I got laying around. Shop Notes #24 suggests strapping an air filter to the back of them and using it as an air cleaner.

What's the difference in this method and picking up a $200 air cleaner?

Seems building a box and mounting it to the ceiling would work just as well, but that maybe just a bad assumption on my part.

Edit: I didn't overlook the other posts that suggested the same method of using a box fan. I am just curious as to why someone would spend $200 for a air cleaner when you could do it for a lot less. Is it simply to have that pretty box above your head that says JET on the side or do they actually work better?

[leehljp]

Okay, I got a question.
<snip>
What's the difference in this method and picking up a $200 air cleaner?

Seems building a box and mounting it to the ceiling would work just as well, but that maybe just a bad assumption on my part.

Edit: I didn't overlook the other posts that suggested the same method of using a box fan. I am just curious as to why someone would spend $200 for a air cleaner when you could do it for a lot less. Is it simply to have that pretty box above your head that says JET on the side or do they actually work better?

That is my question. What kind of advantage does a $200 have over the box fan and filter?

Speed at cleaning a room or work area? Smaller particles? We have and use room air cleaners but dust still seems to builds up faster in rooms with the small room air cleaners than those without them. For this reason, I am considering even a $200 unit to cut down this fine dust in our house.

[LCHIEN]

Okay, I got a question. I picked up a couple of box fans from HD on clearance last fall for $5 each. The specs say they have 2068 CFM on low, 2610 CFM on medium, and 3226 CFM on high. I have noticed while running these they like to suck up any of the Lowes and HD plastic bags I got laying around. Shop Notes #24 suggests strapping an air filter to the back of them and using it as an air cleaner.

What's the difference in this method and picking up a $200 air cleaner?

Seems building a box and mounting it to the ceiling would work just as well, but that maybe just a bad assumption on my part.

Edit: I didn't overlook the other posts that suggested the same method of using a box fan. I am just curious as to why someone would spend $200 for a air cleaner when you could do it for a lot less. Is it simply to have that pretty box above your head that says JET on the side or do they actually work better?

My guess is that box fans use a flat, wide bladed fan with lots of "space" between the blades and the outside walls.

This kind of fan moves a lot of air in unobstructed places, e.g. there's no ducting and no filters, both sides are open and there's extremely low back pressure.

But because of their open-ness they can't put up any pressure head to speak of. So obstruct it with one or two furnace filter layers, it just won't move any air comparitively speaking. Yeah there'll still be some air you can feel moving, but not thousands of cfm.

If they could really move that much air under pressure, why wouldn't they make DC's with those things?

That's usually the trade off with air movers, volume vs. pressure. To be able to move large volumes with large pressures takes mucho power and expense. But you can move lots of air cheaply as long as you don.t have to push it through anything (pressure head) like your $20 box fan or you can get pressure but not volume, at relatively low cost e.g. you can buy an air compressor for under $20 which will put up 120 PSI to fill your car tires, but it will take ten or twenty minutes to fill a flat tire. But if I needed 120 PSI at 2000 CFM,
we're talking thousands of dollars.

[JimD]

I don't know what the CFMs are for my box fan based air cleaner but it seems like it is enough to make a significant difference. I made my comment about cleaning a lot because I think that is the key difference between my homemade air cleaner and a commercial unit. I have never used the latter but I have noticed they have something like a furnace filter as a pre-filter and then a large bag type filter. I think that the bag type filter would not require nearly as much cleaning as my electrostatic washable furnace filter.

For $150+ savings, I can wash my filter more often, however.

Jim

[JTimmons]

Not arguing....

Here's something though, when it comes to DCs. Most people not knowing think they need a 5 hp dust collector because the shop vac they were running had 5 hp. It works a little differently in that case though. The DC's fan blade produces a higher air flow at lower HP.

This is where my question is coming in. Taking the Delta AP200 for instance. It has 850 CFM at 1/8 HP. I did some checking and found that a 20" box fan has 1/12 HP. Not really that much of a difference in hp 1/12 to 1/8. So the loss of HP in my mind would be made up by the fans large much like the difference in going from a 5 HP shop vac to a 2 HP DC. I wouldn't think that the CFM would be reduced that much from 3000 CFM to under 850 CFM when sticking a filter behind the box fan.

I guess what I'd need is a air flow meter and if I could afford one just to test this I might as well just by the air cleaner.
Then again if someone has already got a air cleaner and a box fan maybe they could offer some test results and see if there is that much of a difference.

[LCHIEN]

Here's something though, when it comes to DCs. Most people not knowing think they need a 5 hp dust collector because the shop vac they were running had 5 hp. ...

I guess what I'd need is a air flow meter and if I could afford one just to test this I might as well just by the air clean...

There's no comparing shop vac HP and DC HP.
the vac guys use some weird way of rating it, they have 5 and 6 HP shop vacs there's no way you can get 5 or 6 HP from a 120V outlet at a standard 15 amps. Maybe a max of 2 HP is achievable from a standard 120V outlet and branch circuit.

Air flow meters are very difficult - I've researched it. you need to measure velocity, basically and then multiply by the tube cross section to get CFM. Then you need to have a tube 20 diameters long before and after the measuring device to get laminar flow or the turbulence will throw the answers way off.

Anyway, high volume, low pressure use big, few blades (like a box fan). If they encounter back pressure the air just leaks back thru the openings between the blades.
High volume, medium pressure (e.g. DC) use impellors with flat or shaped vanes.
Medium volume, low presure, use squirrel cages, like your AC blower and the blowers in air cleaners.
Low volume, medium pressure uses little vaned impellors like your shop vac. These have more blades and inlet and outlet guides to prevent air from leaking back under pressure.
Low vloume, high pressure, uses positive displacement pistons, like your air compressor. They use check valves to prevent air leaking back.

You have to pick the right kind of air mover for the application.

[Jeffrey Schronce]

There's something wrong with the spec. It says 3 speeds, the top speed is 360 CFM, and it says it will change the air in a 20x20x8 room 15 times per hour. It takes 800 CFM to do that, its short by at least a factor of 2.

Are you suggesting that Harbor Freight made a mistake in their publication? Let me introduce you to the HF 2hp DC Manual . . . . LOL!

[pmarion]

Re: Previous topic - I found it, cached, via google. You can find it HERE