B&K 2250 Light Manual do Utilizador descarregar pdf (Página 316)

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Hand-held Analyzer Types 2250 and 2270 – User Manual

Slow Max Maximum time-weighted acceleration or voltage level measured with Linear

frequency weighting and Slow time weighting. It is the highest level occurring

during the measurement time.

Slow Min Minimum time-weighted acceleration or voltage level measured with Linear

frequency weighting and Slow time weighting. It is the lowest level occurring

during the measurement time.

Sound: Any pressure variation that the human ear can detect. Just like dominoes, a

wave motion is set off when an element sets the nearest particle of air into

motion. This motion gradually spreads to adjacent air particles further away

from the source. Depending on the medium, sound extends and affects a

greater area (propagates) at different speeds. In air, sound propagates at a

speed of approximately 340 m/s. In liquids and solids, the propagation velocity

is greater – 1500 m/s in water and 5000 m/s in steel.

Sound level or sound

pressure level: The level in decibels of the pressure variation of a sound. See also decibel.

Std.Dev. The Std.Dev. is calculated as the Standard Deviation of the noise samples

used for statistics. This is either L

or L

sampled every 10 ms, or L

Aeq

sampled every second.

Cpeak

: The time when the peak sound level occurred. ‘C’ denotes that the C

frequency weighting is used.

Threshold Level: Any sound levels below the threshold level do not contribute to the Dose

measurement data. For example, if you set the threshold level to 80, any

sound levels below 80 dB are not taking into consideration by the analyzer,

when it calculates doses and time weighted averages.

Used for calculation of Dose, ProjDose, TWA, TWA

DoseSQ, ProjDoseSQ.

TWA: The Time Weighted Average is the average A-weighted sound level for a

nominal 8-hour working day with Time Weighting S and Exchange Rate 5.

TWA is calculated from the measured LavS5 (taking Threshold Level into

account) and a Reference time of 8 h. Mainly used in the USA for assessing

the noise exposure for a worker during a working day.

TWA

: The Time Weighted Average for a user-defined reference period. TWA

calculated from the measured LavS5 (taking Threshold Level into account)

and the Reference Time. Used, for example, for calculating a Weekly Time

Averaged Level by setting the Reference Time to 40 h.

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B&K 2250 Light Manual do Utilizador Página 316