diy PAPR

[jwmelvin]

I like to use a respirator under the helmet, particularly when doing anything smelly like stick; it seems like most steel welding involves smoke of some sort. I also wear it when grinding, etc. Since I have facial hair, I don't get the best seal on the mask, so I figured I would think a bit about the PAPR (powered air-purifying respirator) approach. I have a 3d printer, so I made some parts to connect the 3M filters to a small blower and then on to the mask. It's kind of amazing what one can do with a 3d printer.

Although I have no actual use yet, it seems to maintain positive flow, but not a lot of excess flow, so it's pretty much what I was going for. It's a 12V fan, so I can make a housing with a battery or I can use a power adapter.



I know, most of you wouldn't want to be tied down to more equipment and all that. But for what I want, it's promising. If you're into this sort of thing, I put my files on thingiverse.

-jason

[henry42]

A PAPR blows air from the top of your head down and around keeping you both cool as well as supplying fresh air. Yeah, your device gives you the air, but not the incredible comfort of not sweating under the hood.

Good build otherwise!

[jwmelvin]

Ah, good point. I thought about trying just the end of the tube at the top of the hood, with no mask. That approach might need a bigger fan and filter.

I appreciate the guidance, thanks.

[farmersamm]

Looks good for filtering particulates. Not sure about toxic gasses though.

I bought a Survivair system about 4yrs ago, and love it. Got lucky, and got a NEW one on Ebay for a very reasonable price.

Main advantage is the oil-less compressor (you do NOT want to hook any air mask to a regular compressor) draws air from an outside area, and supplies the mask through a long hose. Actual clean air is brought to you, not an attempt at filtering bad air in your direct vicinity.

I use it for painting, not welding.....but it would work well for welding. I'd be likely to burn up the hose with slag though

[davec]

Not to crush the inventive spirit here too much, but I am guessing you have no testing into this, unlike all commercially available PAPRs. One big danger in PPE use is a false sense of security - thinking you are protected, when in fact you are not for some reason. PAPRs are designed to supply more air than you can breathe, even when working hard (respiration increases with work level, naturally). That way you always have a positive pressure supply of clean air inside your mask or helmet to keep contaminants out. In the US the standards say you need to supply a min of 4CFM of air for a tight fitting mask like you are showing. Let's say your setup supplies max 1 CFM for arguments sake. When you work hard and are drawing air in at say 3 CFM, where is the other 2 CFM coming from? In all likelihood, at least some of it is coming in from dirty air leaks since that is likely the path of least resistance for some portion of the air. So you can be thinking you are protected, when in fact you are not. So do you know how much air you are supplying, and are you sure everything is leak tight? That is for starters. These things are all tested and certified to the ends of the earth to ensure that they will perform as expected. That is the main reason they cost so much.

You did also mention that you have facial hair. That guarantees that you are not getting a seal with any rubber mask like this one. Trust me on that as there are many studies showing the effect of even a couple days beard growth on the quality of the mask seal to your face. There are solutions for those who will not or cannot shave, but they are much more expensive helmet/hood setups with positive air supplies (and even more air than 4 cfm required...).

Obviously you can and will do whatever you desire, but at least this way you have been informed of some of the obvious risks to your solution so that you don't go into this blindly.
-Dave

[jwmelvin]

Not to crush the inventive spirit here too much...
In the US the standards say you need to supply a min of 4CFM of air for a tight fitting mask like you are showing. ...
So do you know how much air you are supplying, and are you sure everything is leak tight? ...
You did also mention that you have facial hair. That guarantees that you are not getting a seal with any rubber mask like this one.

It would be hard for me to state how much appreciate this type of feedback.

Knowing what I should target for airflow is super helpful. I figure I can measure by filling a plastic bag while timing (a rough measure).

I am sure the connections are leak tight.

The faulty seal when using a passive mask is what motivated me to do this. I understand it is a problem. That said, even a faulty seal is much better than nothing, as “measured” by my subjective experience with a respirator vs. without.

I used this last night for the first time. It seemed quite good, in that it maintained positive flow. But not much excess when I am inhaling so I agree that it should have more. Larger fans are readily available. It’s already a big improvement over a passive mask so I’m happy I tried it. I will improve it.

I also printed a nozzle for a maskless design, to supply fresh air at the top of my hood. Any idea of how much flow I would need for that? I figured some type of shrouds for my hood would help considerably (and would stop spark intrusion on top).

[farmersamm]

I dunno what kind of filter you're using, but here's a rundown of what you might be exposed to. https://access.ewu.edu/Documents/HRR...ed%20Gases.pdf

Is you filter rated for particulates + organic vapors........etc etc etc

You also need to know how many PPM your filter is rated for. If you're in an environment where the PPM exceeds filter capacity, you might as well be without a mask. The filter won't work as it should. Another strike against "purifying" air.

I don't pretend to protect myself from welding smoke/fumes.......I mostly weld outdoors. Depending on which way the wind is blowing...I either get no fumes, or a face full of fumes. Same same on a windless day.......I get it all. But that's my choice. Don't fool yourself into thinking you're protected, when you might not be. Just a heads up.

[TheWeldingConnector]

A PAPR blows air from the top of your head down and around keeping you both cool as well as supplying fresh air. Yeah, your device gives you the air, but not the incredible comfort of not sweating under the hood.

Good build otherwise!

The Miller PAPR has vents in the bottom of the hood right where the mouth is located along with vents at the top of the head.

Edit to add:

You NEED to use 2297 filters with this system. The 22XX series flow way better then the 20XX series and will make a big difference for you if you fan power is limited.

[jwmelvin]

Thanks for the tips. I will also try some 22__ series filters.

[davec]

It would be hard for me to state how much appreciate this type of feedback.

Knowing what I should target for airflow is super helpful. I figure I can measure by filling a plastic bag while timing (a rough measure).

I am sure the connections are leak tight.

You are welcome...Now - How do you know? i see no gaskets of any type, so you are hard plastic on hard plastic. Definitely not likely to make an airtight seal.

The faulty seal when using a passive mask is what motivated me to do this. I understand it is a problem. That said, even a faulty seal is much better than nothing, as “measured” by my subjective experience with a respirator vs. without.

Except this is exactly my point - you THINK you are protected, but in reality you are not (or at least not as much as you think you are).

I also printed a nozzle for a maskless design, to supply fresh air at the top of my hood. Any idea of how much flow I would need for that? I figured some type of shrouds for my hood would help considerably (and would stop spark intrusion on top).

Well, I can give you the figure from the NIOSH regs (min 6 cfm for loose fitting headtops), but without any testing or understanding behind that it means very little. A loose fitting headtop still has a seal, but it is designed to leak a certain amount of air so that it maintains a level of positive pressure inside but doesn't blow up like a balloon. And it still requires extensive testing to make sure it does what you think it does under all normal working conditions. Pumping air into or around an open or nearly open hood will do nothing but give you more false senses of security. Have you considered looking for used systems on Ebay or CL? Might be a much better route than trying to roll your own in the long run.


Edit: The filters you are using are meant to be used by your lungs, in a cycle of breathing in and out. They will see a TON more contaminants when you pull a continuous fan through them and will plug up very quickly as a result, especially in environments with welding fumes, as those tend to plug up filters very quickly. Approved PAPRs have filters that are designed to accommodate the load from the fan constantly pulling air through them. These filters are not made for that.

[rlitman]

That raises a good point. Say you show good flow on this with new filters. A few hours later, when the filters are plugged, how will you know that the flow has now reduced to dangerous levels?

The good news here is that you can place a PAPR away from the worst of the smoke.

A good PAPR system will have a testing device that confirms that you have acceptable flow coming out of the exhilation port even when breathing in. That’s important for peace of mind.

[Insect]

Interesting post, any updates?
So I am designing one with the following parameters.

1) Childs bouncy house blower 25 feet away from me.
2) 1.5" vacuum cleaner type hose to me
3) blows from top of helmet with gentle positive pressure
4) Regulator PVC ball valve on blower, to adjust flow, and a wastegate exit so as to not load the motor too much
5) Some foamy stuff around the heat/helmet interface, just a little, to assist positive pressure.

My goal is to have something an order of magnitude cleaner than nothing, but not go bonkers with it either, as I understand . Anyone progressed on this type of system since 2018?
I imagine it could draw grass pollen & insects in, so it will sit on a chair outside.
I imagine if the motor is stalled and not taking it easy, the brushes may smell, which introduces a new contaminant, so the wastegate passage (free air passage out of blower port) Anyone think of a brushless motor blower off of some appliance that I can use?

[rlitman]

The less flow through a centrifugal pump, the LESS load on the motor. Think about this. When you cover the end of a vacuum hose, stopping the flow entirely, the motor pitch goes UP. That is because the motor is under less load.

A bigger concern is that you should have a system that prevents too much pressure. I’d aim for more leakage, with less sealing to stay safer.

[John Koch]

This is a good idea, and nice work. I'm impressed. Also the feedback here is super helpful and there are some great comments about a false sense of security. My job involves some work in areas with hydrogen sulfide gas levels that are fatal in the event of a mask leak, and I have been doing it for 30 years+, so here are my comments: 1. Baseline is the way to look at it. If you were going to weld without filters, basically anything is an improvement. Even if not 100%, much better than baseline. 2. Don't settle for particulate filters, lots of data on what welders are breathing, and lots of filter technology that will work extremely well. 3. Plugging filters: I think you would probably feel it if the filters plug, but I suggest remaking your adapter to hold 3,4, or more filters. It is not on your face for weight and size, so you can use more. This will increase the time between filter changes and extend the time before the pressure drop through the filters becomes a problem as they start to plug. This will make it easier to run the blower at steady state. 4. Leaks in the system are just not a problem once past the blower. Before that you could try to use soap/water and look for bubbles, or tape the joints, or don't worry about it because you are already way better than baseline. 5. Facial hair: this is not allowed when a mask seal is required for your life, but is not a problem here. Honestly, I would wire a speed control into the power feed for the blower, then dial the air flow up if your face is longer that day or if you want your mask more loose because you got a broken nose the night before in a fistfight over a woman. Note that I deduced that you are a man based on the facial hair comment, though it is possible that you are one of my wife's older female relatives (yikes!). There are some small cheap purpose built fan speed controls (go to thehouseofhydro.com and look at the fan speed controller on their waterproof fan kits) nice to have something packaged and workable every day. Once you get used to this, you can dial up the fan speed to make sure you have positive pressure depending on how hard you are working, how tight the mask straps are, and how the facial hair is impacting the mask seal at that time. 6. I use something called a North BP1000 Series Backpack Adapter which attached to my North mask and allows me to have the filter cartridges behind my back, hoses go over your shoulders, it was cheap and it works for me but I am a hobby welder not a pro. Although I weld so badly I usually have to weld a lot longer. Damn I am jealous of the pros on this forum, I started welding later in life and should have started earlier. Maybe something like this could work in your build, the blower / filter package is not very big or heavy and the ergonomics of having it over the shoulders while welding seems to work well.
Anyway, great idea, great project, great thread, sorry about the rambling, everyone have a great day

[jwmelvin]

This is a good idea, and nice work. I'm impressed.... 1. Baseline is the way to look at it. If you were going to weld without filters, basically anything is an improvement. Even if not 100%, much better than baseline. 2. Don't settle for particulate filters, lots of data on what welders are breathing, and lots of filter technology that will work extremely well. 3. Plugging filters: I think you would probably feel it if the filters plug, but I suggest remaking your adapter to hold 3,4, or more filters....

Thanks for the encouragement and suggestions. I did make another version that uses a larger blower, and it works better. Definitely a surplus of flow. I’ve been staying pretty clean shaven for the past year so haven’t needed the PAPR as much, but with the higher flow, I can have it feed in my hood from the top, and maintain cleaner air and a nicer environment in the hood. I have a leather back attached to my hood, which helps constrain the flow.