BRUEL & KJAER 2230 - Max;Min Hold Measurements; Elapsed Time Determination

Select a FSD value to suit the measured SPL (i.e. without overload). Press RESET "All"
to start a new Leq measurement. During the Leq measurement the current SPL can be
compared with the measuring range of the Sound Level Meter by reading the quasi-
analogue display. The current Leq value can be read by setting DISPLAY to "Leq". The
measurement can be interrupted (and the display frozen) by setting the instrument to
"Pause".
The measurement period can be calculated from the corresponding Leq and SEL values
using the diagram on the back plate, see section 3.5.8. The SEL for this same measu-
rement period can be obtained by setting the DISPLAY switch to "SEL". The measure-
ment time period is only limited by the battery life i.e. at least 8 hours.
A change in FSD setting will also reset the instrument i.e. start a new Leq measure-
ment.
3.5.7. Max. or Min. hold Measurements
Set the controls on the Sound Level Meter as follows:
POWER:
REF
.-OPERATE:
EXT. FILTER:
DISPLAY:
"On"
"Operate"
"Out"
"Max." or "Min."
Set other switch functions according to measurement conditions and to conform to the
appropriate standard.
Press RESET "Max./Min." (or "All") to start the measurement period.
Read the maximum or minimum value on the digital display. The displayed value is the
maximum or minimum level which has occured since the instrument was last reset
(RESET "All" or "Max./Min."). The measurement can be interrupted by setting the ins-
trument to "Pause".
Max. or Min. hold measurements can be carried out at the same time as Leq and SEL
measurements. When the Max or Min value alone has to be reset, select RESET
"Max./Min.".
3.5.8. Determination of the elapsed time.
20
A conversion table similar to the one printed on the rear of the Sound Level Meter is
shown in Fig.3.8 and may be used as follows:
1. Read displayed Leq and SEL values
2. Calculate the difference value SEL - Leq
3. Locate this last result on the upper side of the scale, and read the measurement
duration indicated on the lower side of the scale.
Example (See Fig.3.8). With a displayed Leq and SEL of 60 dB(A) and 94 dB(A) respecti-
vely, the difference SEL - Leq = 34 dB. This corresponds to an elapsed time of ap-
proximately 42 min.