When investing I wear a 3M half-face respirator with two particulate
filters. I’ve been using the same filters for about 12 months and
invest a couple time a week. It occurred to me that I should probably
change the filters occasionally. They don’t seem at all obstructed.
How do I know when it’s time to change them?
Mark
Hi Mark,
How do I know when it's time to change them?
The filters I use have a “use by date on them”, when I am not using
them I store the filters in zip-lock plastic bags.
Regards Charles A.
Mark,
When investing I wear a 3M half-face respirator with two particulate filters. I've been using the same filters for about 12 months and invest a couple time a week. It occurred to me that I should probably change the filters occasionally. They don't seem at all obstructed. How do I know when it's time to change them?
Generally speaking with Particulate filters, they can be used until
you sense resistance or you have leakage around the mask. In industry
often a resistance meter is used to accurately gauge this. Often pure
particulate filters have a pre filter that is snapped over the final
filter. It is common to change the prefilter several times before the
main filter needs replacing. Also think these masks are designed for
people to wear 8 hours a day 5 days a week, so I seriously doubt you
are anywhere near the capacity of the filters (Unless you have flour
fights with your partner using the investment powder.
Please note this is different from filters containing an active media
where the change interval will be specified on the cartridge.
In any case these are general guidelines only, if you cannot find
the exact on 3m’s website, they offer an excellent client
service line that will be able to answer all your questions in
reference to the specific respirator that you have.
Mark!
12 months!
These are rated for 8 hours according to OSHA. 3M doesn’t provide
this freely!
3M really needs to step up and display these numbers a bit better. I
have noticed that some of the packaging on the filters will show
this (sometimes it is quite hard to find), but most do
not.
I have contacted 3M about this and they keep referring me to OSHA
because they consider the work we do as a “hobby” unless it is
regulated by OSHA. When I asked about a size chart for the different
face masks on the respirators I was told by several 3M employees to
refer to my OSHA rep’s mask fitness test… When I got upset at the
reference to jewelry making being a “hobby” the conversation was
deferred to my “hostility” which nicely took the conversation off the
topic at hand!!!
When the respirator is not being used you should store it in a air
tight box, because it is still working even though you are not
breathing through it.
Take care of your self Mark
Kenneth
How do I know when it’s time to change them?
The filters I use have a "use by date on them", when I am not using them I store the filters in zip-lock plastic bags.
If you are using something like an organic vapor cartridge and not
just a dust filter your cartridges are probably way past any useful
life. These cartridges are meant for a service life of hours or
maybe a day in the environment where they are necessary but that is
all.
There is no quick and easy way to know the useful life of a
respirator cartridge. Contaminate concentration, contaminate
type(s), humidity, breathing rate and several other factors play
into how long a cartridge is good for. But here is a rule of thumb
from the OSHA website that will possibly get you in the ball park.
Experimental work can allow for a generalization or “rule of thumb”
that broadly defines the service life of cartridges exposed to
chemicals. One such Rule of Thumb for estimating organic vapor
cartridge service life is found in chapter 36 of the American
Industrial Hygiene Association (AIHA) publication “The Occupational
Environment - Its Evaluation and Control.”
It suggests that:
If the chemical’s boiling point is > 70 C and the concentration is
less than 200 ppm you can expect a service life of 8 hours at a
normal work rate.
Service life is inversely proportional to work rate.
Reducing concentration by a factor of 10 will increase service life
by a factor of 5.
Humidity above 85% will reduce service life by 50%
These generalizations should only be used in concert with one of the
other methods of predicting service life for specific contaminants.
James Binnion
James Binnion Metal Arts
They don't seem at all obstructed. How do I know when it's time to change them?
When you are flat on your back on the floor it is well past the time
to change them. 
jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
When the respirator is not being used you should store it in a air tight box, because it is still working even though you are not breathing through it.
Sometimes it depends on your environment. Here in FL, I used to try
to store my masks (I have one for crawling thru attics in my
electrical job, and another for my craftrwork), in large zip bags,
only to discover that, in our climate they will try to grow mold and
mildew, because the plastic parts never really dry, even after a
wipe down. I’ve had better success with the small canvas toolbags.
They hold the masks and their replacement elements protected from
generic dust and dirt, but they breath, so the mask actually dries
out properly.
Ron Charlotte – Gainesville, FL