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Turbidimeters are instruments for measuring for measuring the suspended sediment concentration on marine waters. Fluids can contain suspended solid matter consisting of particles of many differents sizes. We have two of them. The first one is 2m depth and the second one is into a metalic structure with the current meter.
The turbidimeter incorporated into the metalic structure is an OBS-3 and is located approximately 10m depth. OBS-3 detects light scattered between 140° and 160°
AWAC current meter and turbidimeter in a white methalic structure
OBS-3 Specifications
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DINAMIC RANGE |
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0.02 – 2,000 FTU |
OUTPUT SPAN5 MAXIMUM |
0 –5 V f.s |
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Mud (max.)1 |
0.1-5,000 mg/l |
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Sand (max.)2 |
2-100,000mg/l |
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FREQUENCY RESPONSE |
10 Hz |
OUTPUT IMPEDANCE |
<300 Ohms. |
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AMBIENT LIGHT REJECTION |
Optical filtering and synchronous detection |
RMS NOISE AT 0 FTU |
< 50µV |
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TEMPERATURE COMPENSATION |
Solid state temperatura transducer |
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NONLINEARITY3 |
Turbidity (formazin, 0– 2,000 FTU) |
2,0% |
POWER REQUERIMENTS |
+6-15V/12mA |
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Mud (0-4,000mg/l) |
2,0% |
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Sand (0-60,000mg/l) |
5,0% |
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DRIFT |
Time4 |
-3.5% per decade |
OUTPUT FILTER |
20Hz (-3dB) |
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Temperature |
0.05%/ ºC |
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SUPPLY VOLTAGE COMPLIANCE |
250µV/V |
WORKING DEPTH |
2000 meters |
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SETTLING TIMES |
Power up |
< 1s |
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25ºC Step Change in water temperatura |
15s |
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1. Amazon River Mud, D50=10µm. 2. Beach Sand, D50=200µm. 3. Maximum deviation of response from a least-squares straight line, expressed as a percentage of the calibration range. 4. The output will not drift more tan -3.5%, continuous operation, or more tan -3.5% x (duty cycle), burst operation, in the first 2,00 hours. 5. Output span depends on adjustable gain settings. |
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The 2m depth turbidimeter model is an AQUAlogger 210TYT (Integral turbidity probe & temperature sensor)
Barcelona_ELB's second current meter at 2m depth
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Primary Sensors
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Connector version, Turbidity version or Fluorimeter version
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Secondary Sensors
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Temperature
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Power
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Internal 3-cell Lithium Thionyl Chloride pack or bus power
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Communication
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USB 1.0 and RS232 or RS485
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Software
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Windows-based display and logging software
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Sampling
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1s to 256 minutes interval, with burst mode and averaging options
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Data Storage
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Non-volatile EEPROM or Flash
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Storage Capacity
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2 million readings
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Logging Lifetime
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Typically over one year, depending on logging regime
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Acquisition System
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8 channel 16-bit
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Inputs
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2 channels 0-5V buffered; 6 channels 0-2.5V
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Controls
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Digital outputs to control external gain setting, etc
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Communication
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USB 1.1 (no power required) and RS232 or RS485
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Burst Sampling
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Bursts every 1 - 255 seconds or 1 - 255 minutes
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Within-Burst Rate
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From 1 Hz to once every 30 seconds
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Burst Averaging
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Bursts may be averaged to a single data value
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Data Storage
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Non-volatile FLASH
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Storage Capacity
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Nominal 2M sets ¸ number of channels enabled.
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Data Retention
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>10 years
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Logging Lifetime
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Typically 1 year
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Battery
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3 x 3.6V Lithium 'AA' Cell - User replaceable
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Software
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AQUAtalk for Windows for configuration and download or DLL for inclusion in host applications
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Dimensions
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300 mm (11.8") long x 60 mm (2.4") diameter
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Weight
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1100 g (39 oz) in air; 460 g (16 oz) in water
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Attachment
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Single point attachment through mounting hole
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Maximum depth
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1000 m standard, deeper versions on request
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The AQUAlogger 210TYT uses the tried and tested SeaPoint STM turbidity meter. The STM has four switchable gain ranges. These can be pre-set by the user or automatically selected by the AQUAlogger for maximum dynamic range in field deployment conditions.
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Light Source Wavelength
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880 nm
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Scatterance Angles
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15 - 150 degrees
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Linearity
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<2% deviation 0 - 750 FTU
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Measurement Range
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0.01 FTU to >750 FTU over four automatically switched gain ranges. Above 750 FTU the sensor is non-linear.
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Operating Temperature
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0ºC to 50ºC
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Dimensions (exc connector)
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225mm (8.9") long x 70mm (2.8") diameter
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Temperature
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Sensor Type
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Thermistor
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Ranges
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-2-30°C standard, other ranges on request
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Resolution
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better than 0.0015°C
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Accuracy
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±0.05°C
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Time Constant
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max 5 seconds
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Turbidity data are transferred in real time at the Research Institute throught SATELLINE-1870 radio modem.
References:
- OBS-3 Suspended Solids & Turbidity Monitor Instruction Manual, 1991. D & A Instrument Company.
- Basics of optical backscatter (OBS) & turbidity, 2005. D & A Instrument Company.
Manuals:
- AQUAlogger 210 Series Manual. (English)
- OBS-3 Manual (English)
- Satelline 1870 Manual (English)
More information about Vilanova turbidimeter here.