Re: Respirator under helmet
Grandad:
A filter like the 2097 has a little bit of activated carbon in it to kill off the smells from small amounts of chemicals you might encounter. This is referred to as "nuisance odor" in the respirator business. These are not approved for heavy chemical exposure as there is not enough carbon in them for that. They are only meant to take out smells and chemicals in very small amounts (below hazardous levels - thus the "nuisance" qualifier). One key characteristic of activated carbon is that it absorbs pretty much ANY vapor. One of the things you are always fighting against is water vapor. Yes, carbon loves water vapor, and of course it is everywhere. Once the carbon has absorbed as much of all vapors as it can, it no longer really absorbs anything. It doesn't matter if that vapor is paint solvents or H2O or any combination of anything/everything.
Now the other part of the equation is the particulate filter. That is what a filter like the one you list is NIOSH approved for. It removes particles from the air you are breathing - 99.97% of them or greater for this filter (P100 rated). As a particle filter fills up, it gets harder to breathe through. So you have 2 very different failure modes here. When the carbon is used up, you will smell those odors you talk about. When the particle filter is used up, it will be very hard to breathe through. You are apparently seeing the carbon get used up well before the filter plugs up, in your case. So you are still protected against the particles in the air, but you are not getting the benefit of the "nuisance odor" removal anymore at that point.
Options:
1. Replace as you are doing. You get the full benefit of all those features this way.
2. Keep the filters (or the whole mask + filters) in a sealed plastic bag to minimize water vapor exposure when not in use (may extend life, depending on how humid it is in your area). Dry off the mask first, if wet. Frankly this is always good practice, especially with any carbon-containing product. It should help the carbon last longer, especially if you are in a humid region.
3. Keep using it until the filter is hard to breathe through, even though you can smell the stuff getting past the used-up carbon. This could be quite a while, and you may not like that.
4. Switch to a full stacked set with separate full-sized carbon cartridges and particle filters. Much higher capacity so they will last a lot longer, but also a heavier and bulkier.
This all assumes that once you replace the filter, the problem goes away for the 1-1.5 weeks you noted. If that is not true, then you may have a different issue. Also, if you do have a real chemical hazard that is beyond nuisance, then you may not be using the right filter for your application.
Edit: I re-read your post and you mention throat irritation. That may very well be ozone generated from the arc. The carbon will help with that, until it is used up.
Hope this helps.
-Dave
Last edited by davec; 12-16-2016 at 11:34 PM.
-Dave
XMT304 with: 22A Feeder, or HF251 Hi Freq DC TIG air cooled