TAL 114 (L) Rev. 4 - 10090982
DESCRIPTION
Powered Air-Purifying Respirators
must be qualitatively or quantitatively
fit tested in a negative-pressure mode
(with blower off). This will cover use of
the respirator in the powered air-puri-
fying mode operation.
EXPOSURE LIMITS
A listing of acceptable exposure limits
from the following sources:
•
American Conference of
Governmental Industrial Hygienists
(ACGIH)
•
Occupational Safety and Health
Administration (OSHA)
•
National Institute for Occupational
Safety and Health (NIOSH)
•
American Industrial Hygiene
Association (AIHA)
Contact MSA at 1-800-MSA-2222 for
information.
Exposure Limits for Mixtures
The American Conference of Govern-
mental Industrial Hygienists (ACGIH)
publishes the following information to
determine the TLV of a mixture.
First determine the total concentration
of the chemical mixture (CMixture)
from the individual contaminant con-
centrations (C1, C2, C3,…) using the
following formula:
CMixture = C1 + C2 + C3 + …
The TLV of the mixture is found by
using the following formula where T1,
T2, T3,… are the individual contami-
nant TLVs and C1, C2, C3,… are the
individual contaminant concentrations:
Only use these equations if the con-
taminants present are actually mixed.
Some substances do not mix and may
be present separately, for example, in
pockets or at different levels. In that
case, the lowest TLV of the sub-
stances present must be used to
determine the appropriate respirator
category for protection against all con-
taminants present.
8
T
Mixture
=
C
Mixture
+
+
+ . . .
T
1
T
2
T
3
C
1
C
2
C
3
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