Digital Sound Level Meter - Sms-Tork

Digital Sound Level Meter - Sms-Tork
Owner's Manual
Digital Sound Level Meter
Model 8921/8922
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INTRODUCTION
Your digital sound level meter provides
automatic or manual ranging in six meas-
urement ranges from 30 to 130dB. The
unit meets ANSI S1.4 and IEC 651 Type
2 standards, and features 0.1dB resolution.
A background noise absorber permits you
to measure sound leveis accurately even
in the presence of high background noise.
The meter allows you to select between
fast and slow response times and A and
C weighting. A maximum hold function is >
provided.
Jacks on the meter provide both AC and
Dc analog output, while an RS-232 interf-
ace allows you to use an optional cable to
capture sound level data on a PC.
WARRANTY
We warrant this product against defects in
materials and workmanship for a period of
one (1) year from the date of purchase, and
agrees to repair or replace any defective unit
without charge. This warranty does not cover
probes, batteries, or damage resulting from
accident, misuse, or abuse of the product.
FRONT PANEL DESCRIPTION
1. MICROPHONE
LCD DISPLAY
ON/OFF - Power button
REC - Records sound level readings
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MAXHLD - Freezes the maximum
sound level digital reading
C/A - A/C frequency weighting selector
BA MODE - Background noise absorber
F/S - Fast/slow response selector
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DOWN - Adjusts the measurement
range
10. UPPER - Adjusts the measurement
range
11. DC 9V - DC adapter jack
12. CAL - Calibration screw
13. AC OUT - AC analog output jack
14. DC OUT - DC analog output jack
15. RS232 - RS-232 output jack
16. BACKLIT-Back light (8922 only)
FRONT PANEL DIAGRAM
11 121314 15
MEASURING SOUND LEVELS
Sound levels are displayed both digitally and
in a bar graph. The digital display is updated
every 160ms, while the bar graph is updated
every 40ms.
1. Press the ON/OFF key to turn the meter
on. The unit will first display the full
screen and then count down to zero.
The meter will now begin measuring the
current sound levels.
Point the microphone toward the source of
the sound to be measured.
SELECTING A AND C WEIGHTING
When you turn the meter on, it will be in A
weighting mode. A weighting enables the
meter to respond in the same manner as the
human ear, which increases and decreases
amplitude over the frequency spectrum.
Applications for A weighting include OSHA
regulatory testing, environmental
measurement, workplace design, and law
enforcement.
C weighting is suitable for flat response
measurements with no increase or decrease
of amplitude over the frequency spectrum.
Applications for C weighting include the
sound level analysis of engines and
machinery.
Press the C/A key to toggle between A and
C weighting. A small A or C will be
displayed on the right side of the screen to
indicate the current mode.
SELECTING THE RESPONSE TIME
You can select fast or slow response time to
suit different applications and standards.
For example, most OSHA-related testing is
done using slow response time and A
weighting.
When you turn the meter on, it will be in
fast response mode. Press the F/S key to
toggle between fast and slow response. A
small FAST or SLOW will be displayed on
the right side of the screen to indicate the
current mode.
FREEZING THE MAXIMUM SOUND
LEVEL READING
1. Press the ON/OFF key to turn the meter
on.
2. When measuring sound levels, press
the MAXHLD key to freeze the
maximum reading. MAX HOLD will be
displayed. The digital display will
remain unchanged until a higher reading
is detected. Note that the bar graph will
continue to record the current reading.
3. Press the MAXHLD key again to exit
maximum hoid mode.
RECORDING THE MAXIMUM AND
MINIMUM MEASUREMENTS
1. Press the ON/OFF key to turn the meter
on.
2. Press the REC key. REC will be
displayed on the bottom of the screen.
The meter will begin tracking the
maximum and minimum sound level
measurements.
3. Press the REC key again. MIN will
appear on the bottom of the screen and
the minimum sound level measurement
will be displayed. The unit is not
recording at this time, but the bar graph
will continue to show the current
reading.
4. Press the REC key again. MAX will
appear on the bottom of the screen and
the maximum sound level measurement
will be displayed. The unit is not
recording at this time, but th bar graph
will continue to show the current
reading.
5. Press the REC key again to resume
recording and repeat the process.
6. Press and hold the REC key until the
REC indicator disapappears to exit
recording mode.
USING THE BACKGROUND NOISE
ABSORBER
This feature allows you to measure
equipment noise accurately, even in the
presence of high background noise.
1. Press the ON/OFF key to turn the meter
on.
2. Press the MAXHLD key. MAX HOLD
will be displayed.
3. Press the BA MODE key. F will be
displayed to the left of the SPL(sound
pressure level) icon. The digital display
will show the background noise level.
4. Press the MAXHLD key again and MAX
HOLD will be displayed. The meter is
now ready to measure the actual
machine noise.
5. Turn on the machine you want to
measure and note the new sound level
reading. This number represents the
sound level of the device without the
background noise. If there is no change
in the reading, the background noise is
greater than the noise of the device.
6. Press the MAXHLD key and then the BA
MODE key to exit background noise
absorber mode.
BACKLIT KEY (8922 only)
Offer a light for approximate 5 seconds to
make it easier to see the display in the dark.
SELECTING AUTOMATIC AND
MANUAL RANGING
The meter features six measurement ranges
in 10dB steps: 30-80dB, 40-90dB,
50~100dB, 60~110dB, 70~120dB,
80~130dB.
When you turn the meter on, it will be in
automatic range mode and a small AUTO
will be displayed on the left side of the
screen. In this mode, the meter will adjust
the measurement range automatically for
accuracy. The two digit number to the left
of the bar graph on the LCD will show the
low end of the current range.
You can also set the range manually. This
is helpful when you know the measurement
range in advance. The meter will be able to
take readings more quickly, because the unit
does not need to first establish the range
before displaying the measurement.
To adjust the range manually:
1. When measuring sound levels, press
the DOWN and UPPER keys as needed
to adjust the measurement range.
MANU will appear on the display. Note
that the two digit number to the left of
the bar graph will change to refiect the
low of the newly selected range.
2. Press and hold the DOWN or UPPER
key to switch back to automatic ranging.
If the meter is operating in manual range
and UNDR is displayed, the sound is too low
or the range. If UPER is displayed, the
sound is too loud. In either case, you must
adjust the measurement range or your
readings will be incaccurate.
AUTOMATIC SHUTOFF
The meter will turn off automatically after 20
minutes to presserve the battery.
To override this feature:
. Make sure the unit is turned off.
. Press the ON/OFF and MAXHLD
buttons simultaneously.
. When the full display appears, release
{пе MAXHLD button first.
. Release the ON/OFF key. The meter
will remain on until the ON/OFF button
is pressed again.
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The automatic shutoff feature will resume
the next time the meter is turned on.
REPLACING THE BATTERY
When the entire display flashes, the 9V
battery has fallen to a critically low voltage
level and should be replaced as soon as
possible. Use a screwdriver to unscrew the
back battery compartment cover. Insert a
fresh 9V battery and replace the cover.
SPECIFICATIONS
Applicable IEC 651 Type 2, ANSI
Standards S1.4 Type 2
Measurement 31.5Hz~8KHZ
Frequency Range
Accuracy +1.5d8 (Under reference
conditions)
Measurement 30dB-130dB
Level A Weighting
Measurement 35dB-130dB
Level C Weighting
Measurement 6 ranges in 10dB steps:
Level Range 30-80dB, 40-90dB,
50~100dB, 60~110dB,
70-120dB, 80-130dB
Automatic Range | 30-130dB
Time Weighting Fast and slow
Range 50dB
Digital Display 3 1/2 digit LCD, 0.1dB
resolution updated every
0.5 seconds
Quasi-Analog Bar
Indicator
1dB display steps, 50dB
display range, updated
every 50ms
Microphone 6mm diameter Electret
condenser microphone
Analog Output AC: 0.707Vrms (at full
scale), DC: 10mvDC/dB
Size 80mm x 256mm x 38mm
(3" x 11" x 1.5")
Weight 240g(10.30z)
Operating 4-50°C, 10-90%
Temperature Relative Humidity
Storage -20~60°C
Temperauture
Battery QV Battery
Battery Life Approximately 20 hours
Accessories Instruction Manual,
Battery, Carrying Case
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