Rob Wissmann

A new pinned tweet -- all filter testing I've published to date. First, the test chamber write-up. twitter.com/robwiss/status…

@open_erv I still don’t understand. Couldn’t you look at the realtime spectrum (from the microphone) and figure out the contribution of the motor noise by estimating its frequency? As long as it’s different enough from the fan noise freq, that should work.

@robwiss The accelerometer in a phone might work, yeah I might try that, but it won't be as good as a microphone

The V6.0 of the Big Quiet Fan is done, and the motor driver is done enough I can take a basic measure of the noise. At 300 rpm with the filters in place: 42 dBa (44 reading, 39.5 background). 1300 CFM through merv 13. The noise reading is hardly valid, it's so quiet.

@open_erv Not sure what you mean about needing a dynamic microphone connected to an oscope. Have you tried a phone app like AudioTools RTA or REW on a PC? I have a process for using REW on PC with a dayton audio UMM-6.

Also it's clear that the motor is still making most of the noise, probably again due to the driver rather than cogging, but I can determine this by measuring the frequency. I just need a dynamic microphone I can connect to my oscope. They are kind of hard to get...

@SolidEvidence I may be able to help. DM me if you haven’t already got it.

Need a little help. Does anyone know someone that works at the Patuxent Water Reclamation Facility in Crofton, MD that they could put me in touch with? Here's why. 1/

@alvelda @mryoung151 What reason is there to be confident in the IFR? I recall covid initially being thought to have a high IFR, which ended up not being the case.

With a 40% fatality rate on the likely incoming H5N1 pandemic COVID may turn out to be a relatively mild warm-up for the main event. Best strategy would be to get good at airborne virus mitigations BEFORE it arrives. That would include HVAC fresh air and filtration upgrades, in room HEPA filtration, germicidal UV lights, vaccine booster updates and new vaccines that inhibit viral contagion and not just bad outcomes, and yes, masking with quality respirators. There are plenty of excellent reasons why we should already have done this, not the least of which is to have eliminated a COVID truly end that pandemic which today, continues unabated. (note for the doubters that might think me alarmist, former CDC director Dr. Redfield has stated publicly multiple times that as for the incoming H5N1 pandemic, “it’s not a matter of if, but when.”

@JeromeAdamsMD @_CatintheHat @cleanairkits we’ve come up with innovative purifiers based on PC fans and the Corsi-Rosenthal box’s familiar furnace filters to achieve designs with >300 cfm CADR at <40 dBA (they’re quiet).

@JeromeAdamsMD @_CatintheHat The Dyson TP0x models are around 90 cfm CADR. It would add about 2 ACH to a standard size living room, falling short of the CDC recommended 5+ ACH.

With my teens constantly having friends over and us hosting Thanksgiving, I invested in portable HEPA filters and high filtration HVAC filters to keep our air clean. “Living with Covid” doesn't mean living in fear and isolation- it means taking proactive steps to lower risk.

@kprather88 Same for me. Thanks Dr. Prather for voicing the truth on masks and precautions. Many have been kept safe because you spoke out.

One part is luck and a bigger part is preparation. I do not plan to go on an airplane (on ground) or enter a public restroom ever w/out mask. So far: working for me. Please do not lecture me on the fact I may have been asymptomatic. I did all I could to avoid it. Seemed to work.

@lcamtuf Other programming languages let you shoot yourself in the foot. Javascript is constructed entirely of guns and feet.

One cool thing about JavaScript is that arrays are just objects, so they can be used as a sparse hash table: > x = [] > x[1e100] = 'hi mom' Another cool thing about JavaScript is that all numbers are floats > x[0x100000000000001] = 'abc' > x[0x100000000000005] 'abc'

@ArbyCalzony I’m being conservative. There can be a drop going from 1900 -> 2500, depending on the fans and filter area. cleanairkits.com/blogs/news/wha… Also, my experimental method has improved so I really ought to look at those old results again.

@robwiss Oh, and—if you don't mind!—is the lower CADR due to the MERV14 filters being a bit more restrictive, and the filter area at 20x20 already being large enough for the fans to achieve their maximum airflow?

I ran 6 Sickleflow with four Filtrete 1900 16”x20”x1” last night, 300 was my Dust Equiv. CADR number.

@ArbyCalzony I did a similar one once. I would estimate around 400.

@robwiss Sorry for the extremely old thread res, but you seemed like a good person to ask (if this is even reasonable)—suppose you have 9 P14 PWM PSTs running at max rpm in a 3x3 array on top of 4 20"x30" Filtrete 2500s. Is there a way to estimate CADR here from your measurements?

@ParentMishmash A CR box would be preferable. It’s hard for the fan to push air through the unpleated fabric therefore the CADR of this solution will be much, much lower than if furnace filters were used with the same fan.

Here’s a video showing how to use clear tape, an EPDM band and MERV13 filter fabric to make a 4 square foot filter for an HVAC vent Aff link for MERV13 fabric amzn.to/4f2fFsw

@VentiloAngel @dannyashton @Engineer_Wong The better way to measure wattage with the cheap meters (kill-a-watt included) is over the course of several hours. I have found that those measurements give the same result as averaging 60s or so of instantaneous measurements, but ymmv.

@robwiss @dannyashton @Engineer_Wong i'll receive the P3 International P4400-VP in a couple of days. I think my kill a watt overestimate the watt. For the Luggable 7 sickleflow equivalent, i've measured 11,9 W, and Intertek data is 10,8

In August 2024 i've tested the AirFanta and variations with other fans. Result: for the quiet operation it is about the same But Airfanta Fan offer the turbo fast cleaning at max level, so i prefer the Airfanta fan

@VentiloAngel @dannyashton @Engineer_Wong I have had a unit with 2 A14 iPPC-3000 running off a 1A supply for 2 years. I think the problem might be something other than the max amps of the supply. Is it 12V?

@robwiss @dannyashton @Engineer_Wong Thanks. 2 Noctua were damaged with smoke and a burnt smell. My fault, I had used 1A. So I have 2 left out of the 4 I had. will use 2A power. With my Kill-A-Watt, I just measured that for one fan, it’s 9.65W, which comes to 0.8A. much more Tech Sheet, and 3,2 A for 4 fan

@VentiloAngel @dannyashton @Engineer_Wong I have the P3 P4400. Seems like it works.

@robwiss @dannyashton @Engineer_Wong Do you have a good Kill-A-Watt to recommend that isn’t too expensive? I’m not sure if I can trust mine, which is a cheap one. I bought a RioRand, but I doubt the data. Do you think the P3 P4400 would be a good option?

@VentiloAngel @dannyashton @Engineer_Wong If you get a kill-a-watt you can see the draw at the wall.

@VentiloAngel @dannyashton @Engineer_Wong ime the rated amps are for the spike at startup and the draw while running is much lower. You can almost certainly run 4 of those with 2A.

@VentiloAngel @Engineer_Wong Max is crazy loud, we looked into them. Might improve CADR performance at max.

@Engineer_Wong If i have time/energy, soon i'll test the Airfanta variation with P14 Max

@VentiloAngel Cool, like I said, should see no difference. Our filter guards have a very coarse mesh. Can use something like speaker mesh and it still barely impacts cadr.

@robwiss ok thanks, i'll decide if, by curiosity, i'll test with a filterguard to do comparison

CADR for Luggable Sickleflow. Is it with or without the FilterGuard? I need answer , I'll be in the test chamber on Monday. The first day is dedicated to validating 3 machines, and I need to check my sensor calibration to validate my protocol Thanks 🙏 cleanairkits.com/products/lugga…