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Model UT351/UT352: OPERATING MANUAL
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Table of Contents
Title Page
Overview
Unpacking Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols
The Meter Structure
A. Meter Front
B. Side Panel
Display Symbols
Measurement Operation and Functional Buttons
Calibration
Specifications
A. General Specifications
B. Environmental Requirements
Accuracy Specifications
A. Decibel dB
Maintenance
A. General Service
B. Replacing the Battery
Overview
Sound Level Meter Model UT351 and UT352 (hereafter referred to as “the Meter”) is a stable, safe and reliable sound level meter. The Meter is suitable to use in noise control,
quality control, health care and all different kind of environmental noise testing. For example: factory, road, family, musical instrument and all kind of places which need noise
testing.
Unpacking Inspection
Open the package case and take out the Meter. Check the following items carefully to see any missing or damaged part:
Item Description Qt
1 English Operating Manual 1 piece
2 Windscreen 1 piece
3 1.5V Batteries (AA) 4 pieces
In the event you find any missing or damage, please contact your dealer immediately.
Safety Information
This Meter complies with the standards IEC61010: in pollution degree 2, overvoltage category (CAT. I 1000V, CAT. II 600V) and double insulation.
CAT. I: Signal level, special equipment or parts of equipment, telecommunication, electronic, etc., with smaller transient overvoltages than overvoltages CAT. II.
CAT. II: Local level, appliance, PORTABLE EQUIPMENT etc., with smaller transient voltage overvoltages than CAT. III
Use the Meter only as specified in this operating manual, otherwise the protection provided by the Meter may be impaired.
In this manual, a Warning identifies conditions and actions that pose hazards to the user, or may damage the Meter or the equipment under test.
A Note identifies the information that user should pay attention on.
International electrical symbols used on the Meter and in this Operating Manual are explained on page XXX.
Rules For Safe Operation
Before using the Meter inspect the case and accessories. Do not use the Meter if it is damaged, LCD cannot display, the case (or part of the case) is removed or
you consider the Meter does not work properly. Look for cracks or missing plastic.
When using the Meter, must follow the instruction manual.
The internal circuit of the Meter shall not be altered at will to avoid damage of the Meter and any accident.
Replace the battery as soon as the battery indicator appears. When the battery voltage is between 4.5V to 4.8V, low battery symbol display.
When the battery voltage is between 4.5V to 4.3V, low battery symbol blink. The Meter will be automatically power off after 1 minute.
Turn the Meter power off when it is not in use and take out the battery when not using for a long time.
Do not use or store the Meter in an environment of high temperature, humidity, explosive, inflammable and strong magnetic field. The performance of the Meter
may deteriorate after dampened.
Soft cloth and mild detergent should be used to clean the surface of the Meter when servicing. No abrasive and solvent should be used to prevent the surface of
the Meter from corrosion, damage and accident.
Constantly check the battery as it may leak when it has been using for some time, replace the battery as soon as leaking appears. A leaking battery will damage
the Meter.
International Electrical Symbols
Conforms to Standards of European Union
The Meter Structure
(see figure 1)
A. Meter Front
1. Housing
2. Windscreen
3. Microphone
4. LCD Display
5. Functional Buttons
6. Signal output and power terminals
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Model UT351/UT352: OPERATING MANUAL
B. Side Panel (see figure 2)
1. DC Output Terminal: DC analogue signal output. Output impedance is around 100Ω (10mV/dB)
2. AC Output Terminal: AC analogue signal output. Output impedance is around 600Ω (0.707mV/ each range scale)
3. CAL potentiometer: Calibration
4. External DC6V: Using power adaptor DC6V, output plug (·3.5) to plug in the terminal. It can use 4pcs of 1.5V batteries or power adaptor to power up the Meter
Display Symbols (see figure 3)
No. Meaning
1 Data Store is full
2 Date and Time display
3 Data Store
4 Decibel
5 C-Weighting
6 A-Weighting
7 Sound value display
8 Range display
9 Over range
10 Slow response
11 Fast response
12 Low battery display
13 Data Hold is on
14 Auto power off enabled
15 Under range
16 Analogue bar graph display
17 Symbol of Sound Pressure Level
18 Auto ranging enabled
19 Date display
20 Time display
21 Maximum value display
22 Minimum value display
23 Data Store enabled
Measurement Operation and Functional Buttons
Below table indicated for information about the functional button operations
Button Operation Performed
HOLD
A/C
LEVEL
FAST/SLOW
Turn the Meter on and off. Press once to turn the Meter on.
Press and hold for around 1 second to turn the Meter off.
HOLD feature: During sound measurement, press once to
freeze the current reading in the display. Press the button again
to resume normal operation.
During sound measurement, press A/C button to select “A” or “C”
frequency weighting. With “A” weighting selected, the frequency
response of the Meter is similar to the response of the human ear.
“A” weighting is commonly used for environmental or hearing
conservation programs ‘C” Weighting is a much flatter response
and is suitable for the sound level analysis of machines, engines,
etc. Most noise measurements are performed using “A”
Weighting and SLOW Response.
For the Model UT352, press A/C button also could recall and clear
data:
RECALL:
Press and hold this button, the LCD displays the last
Press button to recall additional stored reading.
Press
CLR:
Press and hold A/C button when turning on the
Press to selection of Auto ranging, Manual ranging and auto power off
The Meter is default to auto ranging.
Press LEVEL button to switch to manual ranging. Press button
to toggle from low to high range or from high to low range. Press
and hold LEVEL button to exit the manual ranging mode.
Press to select a FAST (125ms) or a LOW (1 second) response
time. Select FAST to capture noise peaks and noises that occur
very quickly. Select the LOW response to monitor a sound
source that has a consistent noise level or to average quickly
changing levels. Select LOW response for most application.
Press and hold FAST/SLOW button to enable display backlight.
Press and hold FAST/SLOW button again to disable display
backlight.
For UT352, press FAST/SLOW button to store data:
Press HOLD button to freeze data, the LCD displays HOLD
and M symbol and the data being stored.
Press FAST/SLOW to store the data, the symbol RECORD
data stored and the index number.
button to exit the RECALL mode
Meter until the LCD displays CLR and RECORD.
All the data stored will be cleared.
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Model UT351/UT352: OPERATING MANUAL
and the number of index blink for 0.5 seconds.
The Meter will automatically exit HOLD mode.
The Meter can store up to 63 data.
MAX/MIN
Press MAX/MIN to display the maximum or minimum reading.
The display will update only when the measured value exceeds
the value presently in the display.
Pres the MAX/MIN button and the MAX icon will display on
the reading. The reading displayed is the highest reading
encountered since the MAX mode was entered.
Press MAX/MIN button again. The MIN icon will appear
on the display. The reading displayed is the lowest
reading encountered since the MIN mode was entered.
Press the MAX/MIN button again to exit the MAX/MIN
display mode
Press and hold MAX/MIN button to disable or enable auto power
off feature. The Meter will automatically off after approximately
15 minutes of inactivity. The icon display indicates that the auto
power off feature is active.
Calibration (see figure 4)
1. Turn the Meter on.
2. Put the Meter in the “A” weighting mode, FAST response mode, range set to 60~100dB, lock to MAX.
3. Place the microphone onto the calibrator’s 1/2 inches sound source hole.
4. Turn the calibrator on, using 94dB@1kHz standard sound source.
5. Adjust the Meter’s CAL potentiometer located on the side panel until the LCD displays 94.0dB
Specifications
A. General Specifications
Display: 3 1/2 digits, 1999 maximum
Overloading:
Under range displays UNDER
Over range displays OVER
Battery Deficiency:
Change batteries as soon as is displayed.
When the battery voltage is between 4.5V to 4.8V, low battery symbol display.
When the battery voltage is between 4.5V to 4.3V, low battery symbol blink. The Meter will be automatically power off after 1 minute.
Sampling Rate:
Fast Speed: 125 microseconds
Slow Speed: 1 second
Microphone: 1/2” electret condenser
Drop Test: 1 meter pass
Battery: 4 x 1.5V batteries (AA)
Battery Life: Typical 20 hours continuous
Dimension: 273 x 69 x 39mm
Weight: around 386 g (including batteries)
A. Environmental Requirements
For indoor use only.
Altitude: 2000m
Temperature and humidity:
Operating:
0℃~30℃ (≤80%R.H)
30℃~40℃ (≤75%R.H)
40℃~50℃ (≤45%R.H)
Storage:
Safety/ Compliances: EN61326:1997+A1: 1998+A2: 2001+A3:2003, pollution degree 2
Certification:
-20℃~ +60℃ (≤80%R.H)
Accuracy Specifications
Accuracy：±（a% reading + b digits），guarantee for 1 year.
Operating temperature：23℃±5℃.
Relative humidity：≤80%.
Temperature coefficient: 0.1 x (specified accuracy) / 1℃
A. Decibel dB
Function Range Resolution Accuracy Remarks
30~80dB
A-Weighting and
C-Weighting
Sampling Rate
Analogue Bar Graph 30~130dB 1dB
Overloading
DC analogue signal output Output impedance around 100Ω, 10mV/dB Has input terminal
AC analogue signal output Output impedance around 600Ω, 0.707mV/ each scale Has input terminal
Power (HOLD)
LEVEL (AUTO) Selecting auto and manual ranging
A/C (RECALL/CLR) A-Weighting and C-Weighting selection
50~100dB
60~110dB
80~130dB
FAST Sampling Time: 125 microsecond
SLOW Sampling Time: 1 second
0.1dB ±1.5dB Frequency Response 31.5~8kHz
1 dB per scale,
Sampling time: 200 times per second
Over range display: OVER
Under range display: UNDER
Turn on and off the Meter and data
holding
RECALL/CLR features are for model
UT352 only. Press to recall and clear
data
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Model UT351/UT352: OPERATING MANUAL
FAST/SLOW (STORE/BL)
MAX/MIN (Auto ranging)
Selection of fast or slow sampling rate and turn on and off of display
backlight
Selection of maximum and minimum value.
Selection of auto power on and off
STORE feature is for model UT352
only. Press to store data
Maintenance
This section provides basic maintenance information including battery replacement instruction.
Warning
Do not attempt to repair or service your Meter unless you are qualified to do so and have the relevant calibration, performance test, and service information. To avoid
electrical shock or damage to the Meter, do not get water inside the case.
In order not to affect the Meter accuracy or damge to the Meter, do not open the Meter housing
A. General Service
Periodically wipe the case with damp cloth and mild detergent. Do not use chemical solvent.
To clean the terminals with cotton-tipped swab with detergent, as dirt or moisture in the terminals can affect readings.
Press the Meter power off when it is not in use and take out the battery when not using for a long time.
Do not store the Meter in place of humidity, high temperature, explosive, inflammable and strong magnetic field
B. Replacing the Battery
Warning
To avoid false readings replace the battery as soon as the battery indicator appears.
To replace battery:
1. Press the Meter power off
2. Remove the screw from the battery compartment, and then take out the battery door from the battery compartment.
3. Remove the battery from the battery compartment.
4. Replace the battery with 4pcs new 1.5V AA batteries
5. Rejoin the battery door and the battery compartment, and install the screw
○,CCopyright 2008 Uni-Trend Group Limited.
All rights reserved.
Manufacturer:
Uni-Trend Technology (Dongguan) Limited
Dong Fang Da Dao
Bei Shan Dong Fang Industrial Development District
Hu Men Town, Dongguan City
Guang Dong Province
China
Postal Code: 523 925
(see figure 5)
This operating manual is subject to change without notice.
** END **
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