Casella CEL CEL-450 - Manual (Page 15)

the total L Avg of a person’s workplace noise
exposure averaged over a user selected
(variable) period of hours and minutes.
This unit is specified in the USA: OSHA standard
1910-95 published in 1983. When the period is
set to 8 hours, the unit will be shown as TWA.
L Avg Average level over the measurement period.
HML This value is the calculation: L Ceq - L Aeq .
Profiles Up to 4 parameters can be selected to have their
profile stored. Period times between 10 ms and
30 minutes can be selected.
Narrow band models can measure and scan the following parameters
simultaneously.
L
AF
Sound level, with current weightings (A and F
are shown here),
L
AFmx
Maximum level, with current weightings,
L AFmn Minimum level, with current weightings,
L Aeq Equivalent continuous level, with current
frequency weighting.
L
pk
User selectable measured broadband L
Zpk
, L
Cpk
or L Apk presented as a single result.
Cumulative measurements are saved for each user enabled paramater.
In addition, broadband mode allows up to four profiles to be stored for
each result set, with intervals from 10 ms to 30 min. L
N % statistical data
can be measured and stored.
All sound level measurement parameters can be set from the
keypad and the whole measurement range is shown on a single 0 - 140
dB scale. The instruments have 2 Mb of memory, which is used on a
first-come basis. Duration timers can also be set in the main menu,
allowing the instrument to automatically switch off after a pre-defined
time.
1.7 CEL-490 Sound Level Meters
The CEL-490 is recommended for detailed measurements as, in addition
to the CEL-450 capabilities described above, it has more comprehensive
Introduction
CEL-450/490 Operators Handbook - Page 15