Air-Fed Respirator - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: December 10, 2020, 10:45:55 pm
content: I'm looking to build a custom version of this for myself:https://axispro.com/index.php?l=product_detail&p=4How clean is the air delivered from a regular pump? Is there a specific kind I should buy? I don't know much about air compressors and pumps.

author: ConKbot
author_rank: Super Contributor
timestamp: December 11, 2020, 03:58:00 pm
content: Thought Emporium did a DIY PAPR buildThe linked system uses large tubing, so its most likely a centrifugal blower to provide a sufficiently high volume of air and a moderate pressure (more than an axial fan would provide, way below what youd start calling a compressor) So no issue with ensuring an oil-free air supply as you would face with a system that uses high pressure air and a regulator on/near the facepiece. Care must be taken to not get something with excessive pressure or flow rates that exceed the exhale-valve's ability to vent air and keep the pressure in the face mask near atmospheric.Note that either of these systems would not be suitable for IDLH environments. The linked one looks like they are intended for paintbooth type work, which is fine as long as the air in the paintbooth air is kept suitably clean to be able to evacuate in case of equipment failure. (i.e. below the short-term exposure limits), and Thought Emporium's unit is intended as a face mask in normal air. I certainly wouldnt use something self made in a commercial environment, home use the risk is assumed by the user/creator.

author: electromateria
author_rank: Regular Contributor
timestamp: December 11, 2020, 07:43:57 pm
content: Wow, that's very cool. It's not exactly what I need, but thanks so much for sharing, that's a HUGE help!! Those 3d printed files are very valuable to me and will save me countless hoursMy mask isn't for covid, it's for basic shop work. I need a clean supply of air so I don't breathe in metal vapor fumes, metal dust, paint dust and particles etc. I'll look into a little centrifugal blower fan, thanks for the suggestion! I'm playing with the idea of just running a hose far from the worksite with no forced air. Not sure it will work since it would exhale through the same hose instead of the exit vent, but it's easy to test.

author: Benta
author_rank: Super Contributor
timestamp: December 11, 2020, 08:49:55 pm
content: Quote from: electromateria on December 11, 2020, 07:43:57 pmIn that case, a forced "pass-by" air stream would be enough and simple to make. Just a mask with an inlet and outlet sending a steam of fresh air past your nose and mouth.As long as the output tube is long enough, there's no risk of breathing in hazardous stuff from the outside.

author: Bud
author_rank: Super Contributor
timestamp: December 11, 2020, 09:55:02 pm
content: Fine, just dont claim a copyright

author: ConKbot
author_rank: Super Contributor
timestamp: December 12, 2020, 06:54:54 am
content: Quote from: electromateria on December 11, 2020, 07:43:57 pmI'd expect a length of hose of practical diameter to attach to a mask to be surprisingly fatiguing to breathe though.Don't be particularly afraid of the blower thing, I just wanted to make sure that "more isn't always better" was clearly communicated and there is most definitely an upper bound. I.E. don't go hooking up a shop vac with a blower configuration up to a half mask. A typical CPAP prescription may deliver ~10cm water column of pressure (https://www.apneamed.org/blogs/info/how-when-to-have-cpap-pressure-settings-adjusted) my inclination would be to set up the blower with the length of hose you want to run, to a blanked off half mask, so that there was 1-2 or so cmH2O of pressure with it blowing though the exhale valve. There will be more pressure as you exhale, but nothing crazy, and it may drop negative as you inhale, but if the blower is covering a majority of the hose resistance, nothing too difficult.Adjusting the fan speed up or down to what feels comfortable shouldn't be a problem, just trying to get you in the ballpark to not grossly over-spec a blower, and have a safe starting point.