Casella CEL CEL-393 - Manual (Page 93)

3. The ranges of sound pressure level which may be measured
are as indicated under "Measurement Ranges" above.
4. The reference point is 114.0dB SPL.
5. Frequency weightings available are Linear (Flat) and
A-weighted.
6. Time constants are:
F 125 milliseconds,
S 1second
I 35 milliseconds onset and 1.5 second decay,
P <100 microseconds.
7. The effect of vibration as per clause 8.3 of IEC 651 is <6dB.
8. The effect of magnetic fields as per clause 8.4 is <3dB above
the minimum valid reading.
9. Temperature correction for accuracy of ± 0.5dB over the range
-10 to +50 o C is calculated from the formula
Absolute reading = Instrument reading - 0.017(20-t)
When t = temperature in
o
C.
10. The operator has negligible effect upon the measurement if
more than 1m behind the microphone.
11. The effect of relative humidities in the range 30 - 90% is less
than
±0. 5dB relative to 65% RH.
12. Permanent damage may occur at 95% RH and temperatures
outside the range -12 to +60
o C.
13. Recalibration with a suitable calibrator is recommended when
an extension cable is added.
393 Handbook /89.