Re: Protection Factors

[Keith Welch <welch@jlab.org>]

Maybe I misinterpreted the question.  Not "combination respirator" but
"combination OF respirators".  I'm only wondering now, like Tom Odou, which
two respirators are you using in combination with each other?  This seems
like an awfully clumsy approach.  If using a suit, you can't claim a PF
anyway (unless you have done testing and gotten an approved PF for it).
Can you actually get an airfed hood over top of a facepiece respirator and
be able to move your head?  If you're doing this, I would have concerns
about physical stress on the individuals.  But I guess, in principle, if
you did combine for example, a hood with a full facepiece, you could claim
the multiple PF (50,000 or more).  Sounds a little crazy to me.
Personally, I think part III of the table is referring to a "combination
respirator" and is not intended to speak to the kluge combo.

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>This question relates to the proper interpretation of 10CFR20, Appendix A,
>specifically, the table of allowed protection factors for respirators.
>Part III of the same table notes that for use of any combination of
>air-purifying and atmosphere-supplying respirators,  the protection factor
>should be the same as for, " - - - type and mode of operation as listed
>above".   My interpretation of this is that only a single protection factor
>for combined use of respirators is allowed.  That is, one may not simply
>multiply the protection factor for each of the respirators to obtain the
>net multiplicative effect.   Consequently, the maximum protection factor
>allowed is 10,000, [SCBA, full facepiece, PD] regardless of how respirators
>are combined.
>
>Others have the opinion that this is not the case; that in fact, use of two
>different types of respirators in combination permits multiplying
>protection factors of each in order to obtain a net effective protection
>factor.

Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@cebaf.gov
Ph: (757)269-7212
FAX:(757)269-5048