Results 1 to 10 of 10

Thread: Shop air quality on a budget, projects one and two.

  1. #1
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566

    Shop air quality on a budget, projects one and two.

    First one I did some time ago, a cyclone for my shopvac made out of five gallon buckets with less than 20 dollars worth of 2" PVC inside, a couple ferncos on the outside. I can say, doing about the same work in the shop, that I have to clean the filter in my shop vac about 1/3 as often with the cyclone. No cyclone, 3 filter cleanings. With cyclone, 1 filter cleaning, same about of chips and dust to the dump. If you decide to build one of these look super careful at the buckets in the youtube. I couldn't find a bucket with compatible upper rings local, so I cut all the top rings off a team blue bucket so it would fit down inside a team orange bucket.

    https://www.youtube.com/watch?v=1WnitgYFnE0

    Second, just this weekend I built a Corsi-Rosenthal air filter box and my wife loves it. I like it just fine, and I can see it working; but the wife thinks it is the cat's meow.

    For the airfilter box I dropped $150 Fairbanks dollars on a new box fan, 4 20x20 furnace filters, a 2 foot square piece of 1/2 plywood and four caster of the two inch persuasion. I pulled four scraps of 4 inch long 2x4 out of the scrap bin and used close to a whole roll of duct tape.

    https://www.youtube.com/watch?v=aEn2xzlvrdo

    Compared to the PhD in Canada mine has a plywood floor and is on casters, otherwise about the same. I did not make a cardboard baffle for the top because I am good at taping stuff. I did use some wood glue and drywall screws to get the casters mounted to the plywood floor, the rest of the thing is held together with duct tape. When my wife first turned it on we could see particles moving through the air at eye level head directly to the filter. It has been running all weekend, I can see across the shop better and my wife is ecstatic. I have no numeric data on particles suspended in air. The fan motor is not detectably warm.

    I did one lucky thing. I set the 2x4 blocks for the casters half inch back from both edges just because it seemed like a good idea. As I was taping up, the 2x4 blocks are far enough away from the edge that they didn't interfere with the duct tape wrapping around the edge of the plywood onto the bottom face of the plywood.

    I did notice 20x25 furnace filters are cheaper (local to me) per square inch of filter area, compared to the 20x20 filters. And the box fan is slowed down a bit by having to suck intake air through the filter media. For the next one I will use 8 of the 20x25 filters so I have a thing nominal 20 inch square footprint but 50 inches high instead of 20. It will need some interior framework to hold up the fan. If I do it well I will only need duct tape around the edges of the filters to make it airtight. For that next build I will probably use 3/4 ply for the floor, 3 inch casters, and make a baffle for the fan at the top out of half inch ply so I can just run a bead of silicone caulk above the baffle to set the fan on.

    I can see the 50" tall version at the end of my bench just past the trashcan, so as I am planing the whispy bits fall in the trash and the dust can fly across the trash can to the filter. If you build one 50 inches tall before I do please let us know if you had to upgrade the fan.

    My next air quality project (don't hold your breath) will be to build a horizontal cyclone, like this fellow: https://www.youtube.com/watch?v=n2OStvRteRE , except you can skip to 33:00 in his 38 minute video. I am going to start with one sized for my shop vac, but will have an air quality meter and an anemometer (Thank you Larry Frank from I think 2016) and a water tube manometer so I can present it with actual data. If I can make a horizontal cyclone work I can use a less powerful dust collector to achieve similar air quality.

    20211003_182322[1].jpg20211002_211233[1].jpg20211002_211256[1].jpg

  2. #2
    Join Date
    Jan 2010
    Location
    Tampa Bay, FL
    Posts
    3,885
    Nice job, Scott. I never knew these things had a name. Hmmm... The Corsi-Rosenthal air filter box.

    Here's a link from WGBH mentioning the history of these:
    https://www.wgbh.org/news/local-news...-makes-it-easy

    This recent Sawmill Creek post goes into some detail into testing that we did of this type of filter as well as a few commercial ones. The results were very favorable for these inexpensive filters. Really can be built in no time flat.

    UCSD students just did a mass build of 250 of them for classrooms this summer to hopefully reduce the airborne contamination of Covid-19. Good for them.
    https://www.cbs8.com/article/news/lo...1-04b8a8a7dab2

    Here's a few recent links as to their construction:
    https://cleanaircrew.org/box-fan-filters/
    https://www.texairfilters.com/how-to...r-air-cleaner/
    https://cleanaircrew.org/boxfanfilterfaq/

    Personally, with our testing, I would go with 2" thick filters. Better flow and longer longevity. Finding and stacking 20x25" filters like Scott is suggesting sounds like a very good idea. But buying 8 20x25x1" MERV 13 filters might get a little pricey. On their website 3M has Smart MPR 2500 MERV 14 filters in 20x20x1", 20x25x1" sizes, which in theory should filter even better, but I'm never seen them for sale anywhere (though, supposedly Lowes can order them for pickup at their stores). And they don't make 2" versions of those.
    Last edited by Alan Lightstone; 10-04-2021 at 9:15 AM.
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  3. #3
    Join Date
    May 2018
    Location
    Lancaster, Ohio
    Posts
    1,346
    Menards shows Merv 13 in stock in locally $35 range, Merv 12 $15 range different thickness

  4. #4
    Join Date
    Jan 2010
    Location
    Tampa Bay, FL
    Posts
    3,885
    Quote Originally Posted by Ron Selzer View Post
    Menards shows Merv 13 in stock in locally $35 range, Merv 12 $15 range different thickness
    MERV 13 I can find locally. MERV14 they don't stock in my stores here. And none of them seem to stock 2" filters.

    I buy them from Filters-Now.com
    - After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
    - It's above my pay grade. Mongo only pawn in game of life.

  5. #5
    Join Date
    Apr 2013
    Location
    Okotoks AB
    Posts
    3,495
    Blog Entries
    1
    The horizontal cyclone looks very interesting. I'd want to see some actual quantitative testing to see its' effectiveness before going to the considerable amount of work to build one. I can't believe the guy put the blower ahead of the cyclone though. That's just a no brainer.

  6. #6
    Join Date
    May 2018
    Location
    Lancaster, Ohio
    Posts
    1,346
    Quote Originally Posted by Alan Lightstone View Post
    MERV 13 I can find locally. MERV14 they don't stock in my stores here. And none of them seem to stock 2" filters.

    I buy them from Filters-Now.com
    You are right, no 2" Merv 13 in stock, 4", 5", and 6" are shown in stock however
    I use a basic 24"x24"x2" as a prefilter for the bag filters

    edit to add: bag filters are bought once every 10-15 years thru filter supplier at work. Have yet to reach the limit on how dirty they get (measured with a magnetitic gauge permanently mounted) changed due to worry about condition due to age.
    Last edited by Ron Selzer; 10-04-2021 at 11:33 AM. Reason: spelling

  7. #7
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566
    Couple small items.

    With 4 filters at 20x20, my box fan is working a little bit to pull air throught the filter media. My thinking is a larger (but more expensive) filter area will reduce wear and tear on the fan. Also, when I have an array of 8 filters at 20x25 I won't necessarily have to replace them all at once. What I am seeing/reading is in enclosed spaces, like a shop, fine dust particles will eventually drift to the floor or other horizontal surface. Takes a while, but they do settle out eventually. So if say the bottom 4" of my filter box is looking cruddy all the way around I might could just rotate the four filters in the bottom of the stack so I have a crusty band 4" wide half way up and relatively clean filter at the floor level.

    I know some of you all are running similar systems and certainly would like the benefit of your experience.

    I used the best filters I could find at the home store day of build. They did not have visible MERV rating on them. I got one pair at Rheem level 10 that is supposed to filter out virus particles and the other pair at Rheem level 9. Going to a tighter filter will increase felt resistance at the fan and increase my desire to use 8 instead of 4 filters.

    The guy Under Dunn that built the horizontal separator I have a lot of respect for. The first 33 minutes of the vid includes a lot of mistakes he made along the way getting the thing built, and you got to respect him showing us some things that didn't work on the way to coming up with something that does work. I agree the fan should be sucking dust through the separator, not blowing dust into the separator. If someone has adequate power available and adequate headroom in their shop an off the shelf vertical cyclone should be similarly effective for a lot less time and money. At my shop, limited to 110vac, I want to keep the separator and the blower at about the same height as the dust ports on my tools but still have room under the separator to collect chips and fines.

  8. #8
    Join Date
    Feb 2013
    Location
    Tippecanoe County, IN
    Posts
    836
    Quote Originally Posted by Frank Pratt View Post
    ...I can't believe the guy put the blower ahead of the cyclone though. That's just a no brainer.
    Quote Originally Posted by Scott Winners View Post
    ...I agree the fan should be sucking dust through the separator, not blowing dust into the separator...
    That cyclone requires a push through arrangement. There are two dust outlets with each one at a different pressure. Note the two isolated collection compartments. Same as the Harvey.

    Here's a 3D printed version derived from that video.
    Last edited by David L Morse; 10-04-2021 at 3:05 PM.
    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. #9
    Join Date
    Apr 2013
    Location
    Okotoks AB
    Posts
    3,495
    Blog Entries
    1
    Quote Originally Posted by David L Morse View Post
    That cyclone requires a push through arrangement. There are two dust outlets with each one at a different pressure. Note the two isolated collection compartments. Same as the Harvey.

    Here's a 3D printed version derived from that video.
    I totally missed that. But it rules out me making one. I place a lot of importance on separating possibly damaging objects prior to hitting the impeller. Using coarse screens to do that causes too much trouble with clogging

  10. #10
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566
    I kinda hate to bump an old thread. However, I found the correct buckets. My orange/ blue cyclone as above bit the dust a few weeks ago and I have been on a bit of a tear chopping up buckets and cleaning the darn shop vac air filter again.

    If you got a Firehouse Sub Shop near you, you can do it just like the youtube in post one. 4 rings at the top, and a suitable taper. Plus, as built, with the shop vac turned off, separating the buckets is finger tip pressure. An alternative, if your shop vac uses 1.5 inch diameter hose, the current production team blue homestore bucket will fit, once beheaded, into a (some) five gallon paint buckets, with 4 rings at the top of the paint bucket. 2" fittings won't/don't fit good in the bottom of an inverted current team blue bucket.

    Also, once you chop the top of a bucket, instead of fooling with a utility knife for the outside bevel, grab your block plane. Much easier, much quicker and probably safer. Beheading, -or de-ringing- with a back saw is no problem. The bucket you want is food grade HDPE with a 2 inside the triangle, and four rings at the top. I had been asking at other restaurants lately, I guess a lot of food products are no longer packaged in five gallon buckets - but some still are.

    If you aren't running a cyclone/ chip separator yet, this is a gateway drug in a big way.
    Attached Images Attached Images

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •