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Thread: Which Air Filtration is Better??

  1. #46
    Quote Originally Posted by Alan Lightstone View Post
    Interestingly, I happened to watch an episode of Ask This Old House. In it, they built a fan enclosure with four 20"x20"x2" MERV 13 filters and placed it over a 20" fan. Their enclosure consisted of duct taping the filters together with cardboard on the bottom. So an even cheaper method, but certainly not a durable one.

    https://www.thisoldhouse.com/green-h...diy-air-filter
    Attachment 460347

    I actually may build one of these for kicks and place it next to my wide belt sander. If I do, I'll definitely post the air quality results vs time. I can place it on top of the Felder jointer. It's the typical horizontal spot where I put junk. I'll have to remove the crap. Not a bad idea anyway.
    I can't see why those wouldn't be effective for you to some extent, or maybe more. The TOH "build" (term used begrudgingly lol) is basically the same thing as my cart.

    I used the cart yesterday sanding/shaping Walnut with a host of machines and sandpaper. At one point I had the wrong blast open while using the oss.....looked over at the Dylos and PM 2.5 was at 990. I cranked the cart from low w/ speed control knob at low to high with speed control to high. After approx 2-3 minutes the PM was under 200. I hate the smell of walnut being cut so that's how I knew the wrong gate was open.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  2. #47
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    Quote Originally Posted by fred everett View Post
    The TOH "build" (term used begrudgingly lol)
    Yeah, somehow using duct tape shouldn't qualify as a build. I couldn't agree more. That being said, it does work.

    I'll try to post the data later today. I've tested the Jet 1000B, Jet 2000, and the Duct Tape Filter and have calculated time constants, CFM, and Air Exchanges/Hour with MERV 13 modifications. Hopefully they'll show useful information. I think the fan I used is underpowered in the setup. It's the Lasko 20". I think Fred used a more powerful version.

    My caveat. I've known several Nobel Prize winners, and none of them will nominate me for this work. The data is what it is.
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
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  3. #48
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    OK. Attached is the data. Hopefully I've done the calculations correctly. If not, please correct me.

    Clearly adding the outflow MERV13 filter cut the CFM out of the Jet 1000B more than in half. The time constant went from 11.6 to 24.7. So that made things a lot worse, and I removed the second filter.

    Now adding the second inflow MERV13 filter to the Jet 2000 seemed to improve the CFM from 1359 to 1801 (not sure why that should be), and lowered the time constant from 9.6 to 7.2, improving air exchanges to 8.3 per hour which I think is probably pretty good.

    The new 20" Lasko fan with four 2" 20x20 MERV13 filters on its high setting yielded a time constant of 16.0, 814 CFM, and only 3.8 air exchanges/hour. So in my larger shop, this isn't sufficient. Fred used a fan with higher CFM than I did. But as an add on...

    Finally, the kitchen sink approach. I ran the Jet 1000B, the Jet 2000, and the new 20" fan all on high. Started at a higher particle count, and ended the test at a lower count. The biggest test yet. This was pretty awesome. The time constant dropped to 4.0, the CFM was up to 3215, and this yielded 14.8 air exchanges/hr, which is pretty fantastic.
    Air Filter Flow Characteristics.jpg

    As David said TL;DR (I had to look that up, David. It's hysterical, and so true)... ] I don't regret putting together the duct tape air filter. It does seem to help, and whatever removes the fine dust from the air the quickest, so I can take off the respirator is a good thing in my book. And turning all three air cleaners on high is great.
    Last edited by Alan Lightstone; 07-13-2021 at 9:23 PM.
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  4. #49
    Quote Originally Posted by Alan Lightstone View Post
    OK. Attached is the data. Hopefully I've done the calculations correctly. If not, please correct me.

    Clearly adding the outflow MERV13 filter cut the CFM out of the Jet 1000B more than in half. The time constant went from 11.6 to 24.7. So that made things a lot worse, and I removed the second filter.

    Now adding the second inflow MERV13 filter to the Jet 2000 seemed to improve the CFM from 1359 to 1801 (not sure why that should be), and lowered the time constant from 9.6 to 7.2, improving air exchanges to 8.3 per hour which I think is probably pretty good.

    The new 20" Lasko fan with four 2" 20x20 MERV13 filters on its high setting yielded a time constant of 16.0, 814 CFM, and only 3.8 air exchanges/hour. So in my larger shop, this isn't sufficient. Fred used a fan with higher CFM than I did. But as an add on...

    Finally, the kitchen sink approach. I ran the Jet 1000B, the Jet 2000, and the new 20" fan all on high. Started at a higher particle count, and ended the test at a lower count. The biggest test yet. This was pretty awesome. The time constant dropped to 4.0, the CFM was up to 3215, and this yielded 14.8 air exchanges/hr, which is pretty fantastic.
    Air Filter Flow Characteristics.jpg

    As David said TL;DR (I had to look that up, David. It's hysterical, and so true)... ] I don't regret putting together the duct tape air filter. It does seem to help, and whatever removes the fine dust from the air the quickest, so I can take off the respirator is a good thing in my book. And turning all three air cleaners on high is great.
    I'm using an 18 Inch Industrial rated at 4000 cfm and 1" 20x20 merv 12.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  5. #50
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    Quote Originally Posted by fred everett View Post
    I'm using an 18 Inch Industrial rated at 4000 cfm and 1" 20x20 merv 12.
    Fred:

    Do you have a source for that fan, or a link? Clearly much more powerful than the one I've been using. I definitely will need speed control on it. I like the thought of it quietly running in the background.

    Thanks,
    Alan
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  6. #51
    Quote Originally Posted by Alan Lightstone View Post
    Fred:

    Do you have a source for that fan, or a link? Clearly much more powerful than the one I've been using. I definitely will need speed control on it. I like the thought of it quietly running in the background.

    Thanks,
    Alan
    I bought this fan off Amazon. The speed controller I used was also Amazon. I removed the speed controller components, cut the cable off the fan and hard-wired everything in my own box so I'd have a single pwr cable and a cleaner look.

    It is nice to have the fan running on low. I had it on hand cutting dovetails last week....didn't need it of course.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  7. #52
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    I may try that Fred. Especially for when using the wide belt sander, I'd love to get the particle counts down to ambient quicker. Though I hate additional noise pollution.

    David, a few questions, if I may impose.

    1.) Why would adding a second MERV13 filter in series to the inflow of the Jet 2000 increase CFM? It should provide more resistance. I would think it should have decreased flow. Is this likely measuring error?

    2.) Doing a calculation that I could find online, it appears that the worst AQI that I encountered in testing was 5.7 (This was with small particle count of 2900, large particle count of 1296). Is this calculation correct? If so, what useful value is there in AQI? I mean an AQI of 5.7 is supposedly a very good/safe level of AQI for breathing (the good range being 0-50), yet there's no way I would want to breath that without a respirator in my workshop. Or did I just calculate that incorrectly.
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  8. #53
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    Quote Originally Posted by Alan Lightstone View Post

    1.) Why would adding a second MERV13 filter in series to the inflow of the Jet 2000 increase CFM? It should provide more resistance. I would think it should have decreased flow. Is this likely measuring error?
    Well, the higher composite efficiency of two filters should result in a higher clean air output if the raw CFM doesn't decrease too much, but it would only be a slight increase, not the large difference you have. Keep in mind that there are still some uncontrolled variables in this simplified method. Overall, that looks like good data when you consider all of the uncertainty in the process.

    2.) Doing a calculation that I could find online, it appears that the worst AQI that I encountered in testing was 5.7 (This was with small particle count of 2900, large particle count of 1296). Is this calculation correct? If so, what useful value is there in AQI? I mean an AQI of 5.7 is supposedly a very good/safe level of AQI for breathing (the good range being 0-50), yet there's no way I would want to breath that without a respirator in my workshop. Or did I just calculate that incorrectly.
    Using this method I calculate a PM2.5 of 16, and PM10 = 448. From here I get 59 for the AQI if I only look at PM2.5 but including the PM10 value the AQI is 330! Are you sure of the 1296 number?


    Quote Originally Posted by Alan Lightstone View Post
    Fred:

    Do you have a source for that fan, or a link? Clearly much more powerful than the one I've been using. I definitely will need speed control on it. I like the thought of it quietly running in the background.

    Thanks,
    Alan
    Matthias Wandell has several videos on his woodgears.ca website about adding a shroud to some similar fans to get better airflow through a filter. If you're going to the trouble of building something that's something you might want to look into.
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  9. #54
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    Quote Originally Posted by David L Morse View Post



    Are you sure of the 1296 number?
    Yes, I checked the picture I took of the readings. The 1296 was correct. Or at least what the Dylos read. My calculations of PM2.5, however look wrong. Thanks for the correction. If that PM 10 of 330 was indeed in my shop, boy you really don't want to be breathing that in without a respirator. If you're fond of your lungs, that is. I usually focus on the smaller particles, but you don't want to coat your upper airways/bronchi with the larger ones either.

    And just think, this is what the air in China looks like, on a typical day. While workers are actively making all the machines and other stuff that we buy:
    DSC_1951.jpg

    I may run another test with all 3 filters on, generating a large starting particle count again. Getting kinda boring sanding boards into dust.

    Quote Originally Posted by David L Morse View Post
    Matthias Wandell has several videos on his woodgears.ca website about adding a shroud to some similar fans to get better airflow through a filter. If you're going to the trouble of building something that's something you might want to look into.
    I'll watch those. Thanks.
    Last edited by Alan Lightstone; 07-16-2021 at 9:20 AM.
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  10. #55
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    Quote Originally Posted by Alan Lightstone View Post
    Yes, I checked the picture I took of the readings. The 1296 was correct. Or at least what the Dylos read. My calculations of PM2.5, however look wrong. Thanks for the correction. If that PM 10 of 330 was indeed in my shop, boy you really don't want to be breathing that in without a respirator. If you're fond of your lungs, that is. I usually focus on the smaller particles, but you don't want to coat your upper airways/bronchi with the larger ones either.
    IIRC, the NIOSH limit for hardwood total respirable material is 1mg/cubic meter, so your shop is roughly one third of what's allowed for working 8 hours per day.

    And just think, this is what the air in China looks like, on a typical day. While workers are actively making all the machines and other stuff that we buy:
    And that's much more dangerous substances than wood dust. Emissions from fossil fuel combustion, which include not only nasty carbon compounds but also heavy metals, silica and asbestos from mining and construction, tire dust, CO, NO2, O3, etc. are particularly bad actors. It's this kind of PM2.5 that drives the WHO recommendations. Wood dust has not shown correlation with heart disease, stroke, diabetes, etc. like industrial pollution has. It's mostly lung issues, and those correlate with total level not just PM2.5.
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  11. #56
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    Ok. Did a few things.

    I purchased a new, higher velocity fan on Amazon. Not sure if this fan is the optimal one, but the one Fred suggested on Amazon is now only available as one used one. Really didn't want to go that route. So instead I purchased a NewAir 3000CFM fan (at least that's what the ad says). I also purchased the variable speed controller that Fred recommended.

    Using the Ask This Old House "Building approach", I put it together with duct tape and cardboard. I will actually build a wood enclosure for it later. So, in theory, this should provide more air flow than the Lasko Power Plus original fan that I had purchased.

    I've attached a new table with the new "high velocity" fan included. Bottom line, it's performance was identical to the Jet 1000B with the MERV 13 filter on it. Within the margin of error for sure. For a fraction of the cost. So, interesting.

    The noise produced from the NewAir fan is definitely more annoying than the Lasko, even at the lowest speed setting. Just produces a more annoying frequency, FWIW.

    Now when I put all three air filters on high, the results are great. 3138 CFM, 14.5 air exchanges/hr. It may actually be better. I'm not sure if my starting the test with much higher particle counts makes the numbers look worse. The first 2-3 minutes of all units being on was very, very impressive. The particle counts dropped from 5417 to 2231 in only 2 minutes.

    So I'm going to keep the third air cleaner, with it placed next to the wide belt sander. I may actually get a timer to have it run a few times a day for 30 minutes or so. I'd imagine the baseline particle counts should be stellar with that approach, with a minor use of electricity. On high the fan uses 113 watts. On the lowest setting it only draws 77 watts. Which is a lot in my energy efficient house, but still a low number in the greater scheme of things (about $0.03/day).

    So, I absolutely agree with Fred, and the Shophacks website that this unit does work very well, and can be built (or "Built") quite inexpensively. But fan selection is important.

    Air Filter Flow Characteristics.jpg
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  12. #57
    Quote Originally Posted by Alan Lightstone View Post
    Ok. Did a few things.

    I purchased a new, higher velocity fan on Amazon. Not sure if this fan is the optimal one, but the one Fred suggested on Amazon is now only available as one used one. Really didn't want to go that route. So instead I purchased a NewAir 3000CFM fan (at least that's what the ad says). I also purchased the variable speed controller that Fred recommended.

    Using the Ask This Old House "Building approach", I put it together with duct tape and cardboard. I will actually build a wood enclosure for it later. So, in theory, this should provide more air flow than the Lasko Power Plus original fan that I had purchased.

    I've attached a new table with the new "high velocity" fan included. Bottom line, it's performance was identical to the Jet 1000B with the MERV 13 filter on it. Within the margin of error for sure. For a fraction of the cost. So, interesting.

    The noise produced from the NewAir fan is definitely more annoying than the Lasko, even at the lowest speed setting. Just produces a more annoying frequency, FWIW.

    Now when I put all three air filters on high, the results are great. 3138 CFM, 14.5 air exchanges/hr. It may actually be better. I'm not sure if my starting the test with much higher particle counts makes the numbers look worse. The first 2-3 minutes of all units being on was very, very impressive. The particle counts dropped from 5417 to 2231 in only 2 minutes.

    So I'm going to keep the third air cleaner, with it placed next to the wide belt sander. I may actually get a timer to have it run a few times a day for 30 minutes or so. I'd imagine the baseline particle counts should be stellar with that approach, with a minor use of electricity. On high the fan uses 113 watts. On the lowest setting it only draws 77 watts. Which is a lot in my energy efficient house, but still a low number in the greater scheme of things (about $0.03/day).

    So, I absolutely agree with Fred, and the Shophacks website that this unit does work very well, and can be built (or "Built") quite inexpensively. But fan selection is important.

    Air Filter Flow Characteristics.jpg
    As you point out, the nice part about putting a furnace filter air clearer together is the cost. Stinks about the annoying frequency, but using it to control baseline while the BS runs sounds like a good plan.

    This may be related to my shop, but it seems my cart also improved finishing. Could be a placebo affect, but it seems less dust is settling on my finishes.
    Thanks,
    Fred

    Seasoned professional possessing unremarkable proficiency at innumerable skills.

  13. #58
    shop fox lasted a month, woodcraft didn't give a crap I finally got a board from shop fox but motor damaged when board went. Ended up throwing the dam thing away

  14. #59
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    OK. Been busy making multiple test runs, to test the air cleaner / filter combinations. With an extreme amount of help from David, I think we have some pretty good data here, which makes some valuable points, IMHO.

    Also, I'm getting a little tired of turning boards into toothpicks on my wide-belt sander. I may do a few more runs with the Jet 2000 with the 2 MERV 13 filters on it, but the data from the single test seems reasonable.

    Here's the results. And the type keeps getting smaller and smaller...
    Summary Air Filter Tests 1.jpg

    Since it's hard to read, let me summarize things.

    1.) The Jet 1000B with using a MERV13 filter cleans small particles at about 902 CFM. It's filter efficiency is about 67%.

    2.) The addition of a second, smaller MERV13 filter over the outflow duct improves filter efficiency to 79%, but at the significant cost of reduced air flow. So small particle clean air CFM drops to 723 CFM. And the room takes 32% more time to clean the air. So this makes things worse. Don't add a second filter to the outflow duct on a Jet 1000B.

    3.) The Jet 2000 generates small particle clean air at about 1639 CFM with the addition of a second 2" MERV13 filter to the intake side. I would assume that these numbers would be even better if I made a box with four MERV13 filters on the intake side of that. Although, it would get huge. This was a winning move. That's a very good flow rate, with efficiency of 82%. This I would definitely recommend.

    4.) The duct taped together science fair project of four MERV13 20x20x2" filters with a NewAir High Velocity 18" fan on top produces small particle clean air at 830 CFM. So very similar to the Jet 1000B at much reduced cost. It's filter efficiency was 73%, which was better than the Jet1000B at 67%. So I agree with Fred, and the ShopHacks site that this is a winning combination. Fred's larger fan I would think would produce even better results. I would recommend a fan with about 3000 CFM (the company's inflated results). 20" would be even better than 18", though you might have to enlarge filter dimensions.

    5.) All 3 air cleaners on at the same time produced stellar results. They produced small particle clean air at 3237 CFM. This would clean the air from about 6000 0.5 micron particles to about 300 (less than the typical ambient air in my workshop) in 11 minutes. I think that's pretty amazing. And since I never let the particle counts get nearly that high, and would have all three units on while working, I think the air would get clean in maybe 5 minutes.

    6.) Adding the fan speed control that Fred suggested is a winner. It enables you to keep the fan on at a low level in the background and achieve impressively clean air.

    7.) I also added a 110V digital timer and have it set to turn the fan on at the low setting for 30 minutes, 3 times a day. My background 0.5 micron counts in the workshop are now approximately 10-15 instead of 500. I'm sure my lungs will be very grateful for this, and the electricity expenditure will be virtually nothing. Here's the link, but there are many out there. This one is nice because you can program multiple on/off cycles per day: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

    So, for all of you who gave up reading this tome 5 paragraphs ago:

    The four filter box / fan combination is worth building.
    Changing your filters on your air cleaners to MERV13 improves things dramatically. Just duct tape on a 2" MERV Filter and replace the native filter with a MERV13 one.

    Again my thanks to Dave Morse for his great help, and to Fred for starting this. I'm glad I could confirm the data with a bigger workshop.
    Last edited by Alan Lightstone; 07-22-2021 at 10:05 AM.
    - When God closes a door, he opens a window. Our heating bill is outrageous & six raccoons got in last night. Please God, this has to stop!
    - Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

  15. #60
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    Alan — Thanks for all the testing and info! Super helpful for someone like me trying to figure out the next step in improving my shop air quality.
    There is a very fine line between “hobby” and “mental illness.” - Dave Barry

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