These instruments are constructed to withstand some of the
toughest industrial conditions with cases formed from a polyester/
polycarbonate material, giving them a high resistance to damage. Data
integrity is further protected by the use of robust electret microphones.
1.6 CEL-450 Sound Level Meters
The CEL-450 is ideal for on-site noise surveys and can also monitor
personal noise exposure in accordance with European - ISO or USA -
OSHA and DOD standards. The following weightings can be set:
RMS: A, C, Z (see section 1.1) weightings,
Peak: A, C, Z weightings,
Time: F (fast), S (slow), I (impulse),
Q: 3, 4, 5, 6 energy conversion factor.
Broadband models can measure all of the following parameters simul-
taneouslywith a single time constant.
L
AF
Sound level, with current weightings (A and F
are shown),
L
AFmx
Maximum level, with current weightings,
L
AFmn
Minimum level, with current weightings,
L
Aeq
Equivalent continuous level, with current
frequency weighting,
Together with L
Ceq
is used for HML calculations
of heaing damage,
L
AIeq
Equivalent continuous level, with impulse
weighting,
L
Zpk
Linear peak,
L
AE
Sound exposure level (sometimes known as SEL),
L
Ep,v
Noise dose normalised to a user selected
(variable) period of hours and minutes,
When the period is set to 8 hours, this will be
shown as L
ex,8h
.
L
Tm3
Cumulative average of fast weighted maximum
values taken over 3 s periods (Taktmaximal 3),
L
Tm5
Cumulative average of fast weighted maximum
values taken over 5 s periods (Taktmaximal 5),
TWA
v
Time Weighted Average is the normalised time
averaged sound pressure level with the selected
frequency and time weighting that represents
Introduction
Page 14 - CEL-450/490 Operators Handbook
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