It’s rarely a wise idea to put a plastic bag over one’s head, but when the choice is between that and possibly being exposed to a dangerous virus, you do what you have to. So you might as well do it right and build a field-expedient positive pressure hood.
We’ve all been keeping tabs on the continuing coronavirus outbreak in China, but nobody is following as closely as our many friends in China. Hackaday contributor [Naomi Wu] is
in from Shenzhen, posting regularly from the quarantined zone, and she found this little gem of ingenuity from a [Doctor Cui] in one of the hospitals in Wuhan. Quarantines and travel restrictions have put personal protective equipment like masks and gowns in limited supply, with the more advanced gear needed by those deal most closely with coronavirus patients difficult to come by.
There’s no build information, but from the pictures we can guess at what [Dr. Cui] came up with. The boxy bit is an AirPro Car, a HEPA filter meant to clean the cabin air in a motor vehicle. He glued on a USB battery pack to power it, used a scrap of plastic and some silicone adhesive to adapt a heat-moisture exchange filter from a mechanical ventilator to the AirPro’s outlet, and stuck the tube into a plastic bag sealed around his neck. The filter provides dry, positive pressure air to keep the bag from fogging up, and to keep [Dr. Cui] from asphyxiating. Plus he’s protected from droplet contact, which is a big plus over simple paper masks.
With the news always so dark, it’s heartening to see stories of ingenuity like this. We wish [Dr. Cui] and all our friends in China the best during this outbreak.
Whether it’s the usual pollution of the city, or the fact that your corner of the globe happens to be on fire currently, poor air quality is a part of daily life for many people. One way of combating this issue is with a high quality HEPA filter in your home, but unfortunately that’s not something that everyone can afford to even has access to.
Which is why [Adam Kelly] decided to design this DIY HEPA air purifier that can be built for less than $100. That might still sound like a lot of money, but compared to the $500 sticker price he was seeing for the models recommended by health officials, it’s certainly a step in the right direction. Of course, it’s only a deal if it actually works, so a big part of the project has also been verifying the design’s ability to filter particles out of the air in a timely manner.
To build his purifier, [Adam] found a HEPA H13 rated replacement filter that was cheap and readily available, and started designing a low-cost way to pulling air through it. He eventually went with a 120 mm computer case fan coupled with a step-up converter that can produce 12 V from a standard USB port. Then he just needed to design a 3D printed “lid” which would position the fan so it draws air through the center of the filter.
In terms of testing, [Adam] wasn’t worried about the purifier’s ability to actually filter out smoke particles; unless the manufacturer lied about the capabilities of the filter itself, that part is a given. But he was curious about how effective the fan would be in terms of circulating air through a room.
By installing a pitot tube from one of his drones into the lid of the purifier, he determined the airflow in the center of the filter to be approximately 160 CFM. By his calculations, that means it should be able to circulate all the air in his 25 cubic meter office around 10 times per hour. That’s a promising start, but [Adam] says he’d still be interested in a more detailed analysis of the design’s performance by anyone who might have the equipment to do so.
As he lives in Australia, this project is more than just a passing fancy for [Adam]. He only has to look out the window to see that the air he’s breathing is filled with smoke from the raging bushfires. They say that necessity is the mother of invention, and breathable air is pretty high up on the list of human necessities. Our hat’s off to anyone who sees their fellow citizens suffering and tries to use their skills to come up with a solution.
As if slinging around 40 watts of potentially tattoo-removing or retina-singeing laser beams wasn’t anxiety-inducing enough, now comes a new, scary acronym – LCAGs, or “laser-generated airborne contaminants.” With something that scary floating around your shop, it might be a good idea to build a souped-up laser cutter exhaust fan to save your lungs.
We jest, but taking care of yourself is the responsible way to have a long and fruitful hacking career, and while [patternmusic]’s “Fume Coffin” might seem like overkill, can you go too far to protect your lungs? Plywood and acrylic, the most common materials that come across a laser cutter’s bed, both release quite a witch’s brew of toxins when vaporized by a laser beam. The Fume Coffin clears the air in your shop by venting it to the outdoors after giving it a good scrubbing through an activated charcoal pre-filter and a HEPA polishing element. Both filters are commercially available so replacements won’t be an issue, and the entire thing is housed in a wooden box that gives the device its name.
Since it’s ejecting 200 cubic feet per minute, you’ll have to provide at least that much make-up air, but other than that the Fume Coffin should be a welcome addition to the shop. We’ve seen a few other attempts to handle LCAGs effectively before, including a DIY charcoal and automotive air filter design.