Ideas For Supplied Air Masks

[Paul39]

http://www.practicalmachinist.com/vb/general/fresh-air-hood-sdandblasting-281040/

[Willy Nelson]

I have made something similar which works well thus far
It is a chemical hood with a protective facemask, coupled to an evaporative Air Conditioner via 2 lengths of pool hose. Work well, but I do need to get mine into fresh air, that will be Mk II.

On a side note, but related, you are so lucky being in the States with a huge array of choices, we get nothing here in Australia. I lived in Chicago in 2000, prior to becoming a serious wood turner. Knowing what I know now, I would have bought and brought back tons of stuff. Was on ships for a while, and only brought back household items, oh well, sigh.
Of course, freight kills us as well.
Willy
JArrahland

[BobL]

As far as wood turners are concerned I'd be putting that sort of money towards a decent dust extractor.
Not only would it protect the turner but it would keep the workshop a hell of a lot cleaner and fire safe at the same time and stop the turner transferring wood dust to everywhere else in their house.
OHS protocols stipulate that engineering solutions should be considered before any PPE protection, which is why a dust extractor just makes all round better H&S sense than a mask or hood.
PPE can be used on top of engineering solutions for additional safety but should not be used to avoid engineering solutions.

[SPF]

+1 for what BobL said.

If you are in the workshop, a dust extractor is much better than relying on PPE.

I'm still working through a DIY solution for some spray work (iso) and welding fumes in an area that I can't effectively evacuate with an extractor, but to be honest it is a PITA and I'm only doing it because there are no other good options.

If you are going to make a supplied air mask for use with dusty environments, make sure that you don't get drumming in the cavity that contains the clean air when you move. This can cause dust to get sucked in when you move. The worst types of wood dust contain fungi or bacteria that lodge in your lungs and make your life shorter. And, with this type of dust it doesn't matter how much you breath in - its all bad.

There are a number of other design criteria to be aware of (how to avoid things that kill you) and you should try and find some of the testing protocols used to ensure that the masks achieve the desired results. With that said, if you can get a supply of clean air to your mask at 1-2 bar of pressure and at a good flow rate (which will depend on your setup), then this will generally be better than using a face mask with filters on it. This is because you don't have to rely on the seal integrity of the mask.

[BobL]

There are a number of other design criteria to be aware of (how to avoid things that kill you) and you should try and find some of the testing protocols used to ensure that the masks achieve the desired results. With that said, if you can get a supply of clean air to your mask at 1-2 bar of pressure.


1-2 Bar = ~15 to 30 psi.

I think you mean this pressure to be that of the air supply? but my concern would be if someone was to try and make a sealed mask to maintain a 1 - 2 bar pressure differential.

Given that most ear drums rupture at about 5 psi that will be your first indication something is wrong
Secondly, Rats ventilated with peak inspiratory pressures of 30 cm H2O (0.5 psi) developed a pulmonary edema within 60 min.
The misuse of ventilators even in the <1 psi range in hospitals has done similar things.
This why pressurised mask development is best left to professionals.

[turnerted]

Have a Look at my posting "DIY PP respirator" 14/6/12.I don't know how to do the link thing ,or google it and you should find it.
Ted

[Sturdee]

Have a Look at my posting "DIY PP respirator" 14/6/12.I don't know how to do the link thing ,or google it and you should find it.
Ted

Here is the link (http://www.woodworkforums.com/f8/diy-pp-respirator-154175).


Peter.

[SPF]

1-2 Bar = ~15 to 30 psi.

I think you mean this pressure to be that of the air supply?

BobL - yes I do.

Like you mentioned, if using a press fit mask, encapsulating hood, etc, then there needs to be a fail safe pressure limiting device in the system and this needs to be set to a pressure to suit the setup.

[BobL]

BobL - yes I do.

Like you mentioned, if using a press fit mask, encapsulating hood, etc, then there needs to be a fail safe pressure limiting device in the system and this needs to be set to a pressure to suit the setup.

I would not advise using any sort of pressurised mask. Even though it would be quite difficult to maintain much of a pressure differential around a face mask the pressures needed for lung damage are quite low. A friend of mine who was having breathing issues from pneumonia was put on a conventional oxygen mask in hospital and someone turned the pressure up just a touch over the recommended value and his lungs started bleeding.

Its far safer to forget about any sort of pressurisation and work with an unsealed mask or hood that generates excess flow. 300 L/min sound cover most situations.

[SPF]

I would not advise using any sort of pressurised mask. Even though it would be quite difficult to maintain much of a pressure differential around a face mask the pressures needed for lung damage are quite low. A friend of mine who was having breathing issues from pneumonia was put on a conventional oxygen mask in hospital and someone turned the pressure up just a touch over the recommended value and his lungs started bleeding.


Agreed.

In addition to your point above, the systems that work off filtered compressed (dried) air, also cause nose bleeds and other problems because there is little to no moisture in the air. You have to consider every aspect of the design so you don't cause yourself harm.