Els turbidímetres són instruments que mesuren la concentració de sediments en suspensió en les aigües marines. Els líquids poden contenir matèria sòlida en suspensió que consisteix en partícules de mides molt diversos.
El COO compta amb dos: el primer es troba a 2m. de profunditat i el segon està en l'estructura metàl·lica (foto) al costat del mesurador de corrent. El turbidímetre incorporat en l'estructura metàl·lica és una OBS-3 i es troba aproximadament a 10 m de profunditat. OBS-3 detecta la llum dispersada entre 140 ° i 160 °
Correntímetre AWAC i turbidímetre en una estructura metàl·lica.
Especificacions OBS-3
DINAMIC RANGE |
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0.02 – 2,000 FTU |
OUTPUT SPAN5 MAXIMUM |
0 –5 V f.s |
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 |
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) |
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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El Turbidímetre de profunditat 2m és un AQUAlogger 210TYT (sonda de terbolesa Integral i sensor de temperatura)
Barcelona_ELB second currentmeter at 2m depth
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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El sensor 210TYT del AQUAlogger utilitza el STM Seapoint turbidímetre. El STM té quatre rangs de guany commutable, els quals poden ser preestablert spor l'usuari o automàticament seleccionats pel AQUAlogger per a un rang dinàmic màxim en condicions de desplegament de camp.
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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Les dades de turbidesa són transferides en temps real al COO a través d'un ràdio-mòdem Satelline-1870.
Referències:
- 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)