Thank you for the fulsome reply :-)

I have the opportunity to buy an Allegro Industries remote filtering
multi-user device that is to be connected to a remote air supply. They
supposedly meet OSHA standards for some applications but I don't know
which, maybe all.... Do you have any knowledge of their equipment and
opinion ?

The thing that befuddles me is...how do you weld with an external air
supply, ideally with a hood I guess, and a welding mask ? Or does
someone make a welding hood with allowance for connecting a remote air
supply, or, a respiration hood with capability of installing welding
filters ?

Also where is a non-commercial central source of information about filters ?

Is there anyone besides 3M that is a source of reliable/safe filters ?

Appreciatively,

Courtney

Rosalie B. wrote:
"Steve" wrote:


I agree with this recommendation. Prior to retirement, I had work crews who
regularly used these 3M half face, reusable masks. Depending on the type of
dust they might encounter, they were issued appropriate filter elements. The


For organic materials in a mist (like paint or styrene) where there
might also be dust, the best thing to use is an organic vapor filter
and a dust pre-filter. Otherwise the dust clogs up the organic filter
and it becomes worthless.

For dust, the mask itself will tell you when to change the filters, as
it will become hard to breathe.


could even use these masks, with the right filter, for asbestos dust.
(however, in these situations, they were fully clothed in disposable
coveralls caps and boots.)


Except for lead or silica (as in sand blasting with actual sand)
exposure, I'm not really too happy with people using respirators at
all.

I have sampled many painting operations, and almost never found an
overexposure to anything that would actually require a respirator
unless they were using isocyanates (like in auto body painting) which
are sensitizers and have an extremely low allowable limit, or when the
paint booth was not appropriately ventilated.

Even when they are spraying styrene, it's hard to get an overexposure
unless the person was working somewhere like inside a boat hull
without appropriate ventilation.

For welding or doing something with metallic lead (other than using a
soldering iron), you'd need a metal fume filter. This type filter can
also be clogged easily because metal fume is exceedingly small, so a
pre-filter can be used. This is the same concept as filtering stuff
out of your fuel with first larger pore size filters and then finer
filters.

If your going to encounter anything like asbestos, it is best to turn the
job over to the Pros. Not that it is that difficult, but the is tremendous
scrutiny by local agencies and potential for citations/fines for violating
the rules. (cost me $4000 for removing floor tiles the contained microscopic
"non-friable" asbestos particles. We had taken all the appropriate
precautions but had failed to notify one of the local air quality control
agencies.)


Except for the EPA items, if you are DIY, OSHA is one agency that will
not care if you expose yourself as long as you don't have any
employees.

After all, you can be over exposed to asbestos just because road work
is being done in areas where asbestos occurs naturally in the rocks.

We removed the asbestos shingles on a small house using only family
members, and did not have to comply with any regulations at all. They
even allowed us to take the old shingles to the dump. I would think
that floor tiles would pose less hazard, although of course the
agencies involved go with zero exposure.

Asbestos indoors, especially pipe insulation which easily becomes
friable is a different problem which is a greater hazard and requires
more in the way of protection IMHO.

Oh! I'm glad I'm retired but there are still plenty of opportunity for the
individual boat owner to get in trouble when DIY.

--
My experience and opinion, FWIW


My experience is as 14 years as an OSHA health inspector.

The regulations which are meant to ensure effective respirator use are
quite complicated and onerous, because the respirator absolutely has
to fit properly in order to protect the workers. Correct fitting of
a respirator requires using some kind of challenge environment and
checking to see that when the worker is bending, contorting the body,
sweating or talking that the face to facepiece seal is not broken.

So in general, I'd rather that people just not be in an atmosphere
which is hazardous rather than to think they are protecting themselves
by wearing respirators. There are SO many things that can go wrong
with selecting and wearing a respirator.

The bra cup type respirators (disposable) are very little more use
than the 'railroad respirator' (i.e. a scarf around your nose and
mouth).

I personally couldn't use a half face respirator because I wear
bifocals and the respirator pushed the bifocal part up into the middle
of my eye so I couldn't see anything in middle distance that was lower
than the top of my head. It would mean I'd have to go up or down
steps blind which would be a Bad Thing.

Other things that might keep a person from wearing a respirator which
would actually protect them a

Any kind of scarring under the area where the edge of the mask fits

Eye glasses for a full face respirator because the legs of the
eyeglasses will break the seal. (I had prescription inserts for my
full face respirator)

Any kind of facial hair under the sealing surface - that includes a
low hairline for a full face respirator, and any kind of beard for ANY
respirator

A large nose can also keep some respirators from sealing to the face.

If you want to use a half face respirator, you must always check for
fit each time you put it on by doing a positive and negative fit test.
For one test you cover the exhalation valve and breathe out. The
respirator should lift off your face. For the other test you cover
the total filter area (if your hands are not big enough you have to
use something like a plastic glove to put over the filter), and
inhale. If you can get any air, then the respirator does not fit.
This is a very hard test to do properly and it is tempting to ignore
that little hiss of air that you hear. But it means that air is
coming in that is NOT going through the filters.

Also respirators should be stored in a correctly (not left lying
around to get dust on the sealing surfaces) and should be cleaned
periodically.

The usage of a supplied air respirator is possible for bearded people
if they use the helmet type rather than the half face type. All of
the fit testing requirements are eliminated for the over the whole
head type of respirator - all you have to worry about is that the
compressor delivers enough air so that you don't over breathe it (pull
in air from the bottom). In that case you need an oiless compressor
that is running in a clean atmosphere. Bullard is one type that is
often used by painters. You can also get a device which will cool the
air delivered to the 'helmet'.


grandma Rosalie