From: Mark Holm 
To: russjocoy{at}hotmail.com, atm{at}shore.net
Reply-To: Mark Holm 


The respirator you bought has a combination of a least two elements stacked
in series.  1. is an activated carbon (sometimes called activated charcoal)
element.  This absorbs solvent and other organic vapors.  Once opened, the
activated carbon has a fixed lifetime, so you need to replace them
regularly to keep them effective at absorbing organic vapors.  2. is a
filter pad, perhaps with a porous film on the inside.  This traps particles
such as glass dust and mists (very small droplets suspended in air.)  If
the mists are organic, they may evaporate from the pad, needing then to be
absorbed by the activated carbon,
so you put the dust filter on the outside.

For glass and abrasive work you don't really need the activated carbon part. If
this is how you will be using it, then look for replacement filters that
only are designed for dust and mist.  Of course the combination filters
work too, but
you might be able to save a couple of dollars getting just the dust and
mist replacements.

Do replace the filter elements on whatever schedule the manufacturer recommends.
  AO Safety is a reputable outfit.  Their recommendation will be based
primarily
on keeping you healthy and only secondarily on getting your money.

Mark Holm
mdholm{at}telerama.com

--- BBBS/NT v4.00 MP