Larson Davis Spartan 821, Reference Manual

Page: 36 / 129

Spartan 821/721 Manual Dosimetry Settings 31
This value is only used when you choose Dose as the Mode. The level is used in
the calculation of Dose, Projected Dose, TWA and Projected TWA. See Projected
Noise Dose
,
Noise Dose (Dose)
,
• Threshold Enable
Enable or disable the Threshold Level. This is only used when you choose Dose
mode. When ISO is the selected mode, this setting is ignored and Threshold is
not used.
• Threshold (dB)
Threshold Level (55-100 dB) is only used when you choose Dose as the Mode.
Used to calculate the TWA and Projected TWA.
TWA is a time-weighted average exposure to noise over a period of time (as
opposed to a noise level measured at a specific point in time). For this
measurement, any noise level under the Threshold Level is ignored and the
exchange rate is taken into account. When the exchange rate is 3 dB, TWA(8) is
the constant sound level over an 8-hour period that produces the same amount
of acoustic energy as the actual sound level, only taking into account sound
above the threshold level.
• Shift Time
The length of time in hours of the worker’s shift. This is used in the computation
of Projected Dose, LEP’d, and TWA. See Projected Time-Weighted Average,
P.TWA(x)
,
Projected Noise Dose
• Frequency Weight
The frequency weighting used for all noise level calculations for this virtual
dosimeter except for the peak frequency weighting, which has a separate
weighting selection (A, C, or Z.). The detector for each frequency weighting is
Slow. The LAIeq metric can be displayed on Live and Overall pages.
• Peak Frequency Weight
Select the weighting (A, C, or Z) for the peak frequency.
TAKE NOTE The following table shows properties of the international standard
configurations for virtual dosimeters 1, 2, 3, and 4. The Custom configuration is
also an option for each dosimeter.
Table 3.1 Agency Standard Configuration Values
OSHA-PEL OSHA-HC ACGIH NIOSH ISO 9612 Canada
Mode Dose Dose Dose Dose ISO ISO
Exchange Rate 5 dB 5 dB 3 dB 3 dB 3 dB 3 dB
Criterion Level 90.0 dB 90.0 dB 85.0 dB 85.0 dB 85.0 dB 85.0 dB
Threshold Enable Enabled Enabled Enabled Enabled Enabled Enabled
Threshold 90.0 dB 80.0 dB 80.0 dB 80.0 dB 87.0 dB 85.0 dB
Shift Time 8.0 hrs 8.0 hrs 8.0 hrs 8.0 hrs 8.0 hrs 8.0 hrs
Frequency Weight A-Weighted A-Weighted A-Weighted A-Weighted A-Weighted A-Weighted
Peak Frequency
Weight
C-Weighted C-Weighted C-Weighted C-Weighted C-Weighted C-Weighted
Detector Slow Slow Slow Slow Slow Slow