Casella CEL CEL-310 - Manual (Page 44)

Appendix 1
Type 1
The laboratory and field grade for sound
level meters and personal noise dosimeters
Type 2
The general field grade for sound level
meters and personal noise dosimeters
TWA
This is a parameter used in OSHA
measurements. The time weighted average
is the daily personal exposure level
calculated from the L
AVG and measurement
duration.
In the Dose Badge system, TWA is
calculated for the duration of a “normalised”
8 hour day. TWA replaces the L
EP,d
calculation used for ISO measurement. The
TWA will be:
Lower than the L AVG when the measure-
ment duration is less than 8 hours,
Equal to the L
AVG for a measurement
of 8 hours,
Higher than the L
AVG for measurements
longer than 8 hours.
For example, when measuring according
to OSHA standards, if a shift duration is 6
hours, the measurement should be made
for 6 hours and the TWA reported as the
noise exposure value.
%Dose
The measured noise level expressed as a
percentage of a fixed level.
For example, the reference 100% level
would be a continuous level of 90 dB for 8
hours with an 8 hour Criterion Time and 90
dB Criterion Level.
In the Dose Badge system, %Dose is
a percentage of a fixed dose value based
on the criterion level and criterion time set
by local standards.
For example, the ISO configuration of
the Dose Badge uses a default Criterion
Level of 85 dB and an exchange rate of 3
dB, whereas the OSHA configuration uses
a default of 90 dB and 5 dB.
Therefore, 100% Dose for the ISO
version represents a noise level of 85 dB
for 8 hours and 100% for the OSHA version
represents a noise level of 90 dB for 8
hours.
Page 44 - CEL-310 Dose Badge Users Handbook