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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   

 

 

 

DINAMIC RANGE

 

0.02 – 2,000 FTU

 

OUTPUT SPAN5

MAXIMUM

 

 

0 –5 V f.s

Mud (max.)1

0.1-5,000 mg/l

Sand (max.)2

2-100,000mg/l

 

FREQUENCY RESPONSE

 

10 Hz

 

OUTPUT

IMPEDANCE

 

<300 Ohms.

 

AMBIENT LIGHT REJECTION

 

Optical filtering and synchronous detection

 

RMS NOISE

AT 0 FTU

 

 

< 50µV

 

TEMPERATURE COMPENSATION

 

Solid state temperatura transducer

 

 

 

NONLINEARITY3

Turbidity

(formazin, 0– 2,000  FTU)

 

2,0%

 

 

POWER

REQUERIMENTS

 

 

 

+6-15V/12mA

Mud

(0-4,000mg/l)

 

2,0%

Sand

(0-60,000mg/l)

 

5,0%

 

DRIFT

Time4

-3.5% per decade

 

OUTPUT FILTER

 

20Hz (-3dB)

Temperature

0.05%/ ºC

 

SUPPLY  VOLTAGE COMPLIANCE

 

250µV/V

 

WORKING  DEPTH

 

2000 meters

 

 

SETTLING TIMES

 

Power up

 

< 1s

 

25ºC Step Change in water temperatura

 

                                                                            15s

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.

 

 The 2m depth turbidimeter model is an AQUAlogger 210TYT (Integral turbidity probe & temperature sensor)

 

Barcelona_ELB's second current meter at 2m depth

 

Specifications
Primary Sensors
Connector version, Turbidity version or Fluorimeter version
Secondary Sensors
Temperature

 

Power
Internal 3-cell Lithium Thionyl Chloride pack or bus power
Communication
USB 1.0 and RS232 or RS485
Software
Windows-based display and logging software
Sampling
1s to 256 minutes interval, with burst mode and averaging options
Data Storage
Non-volatile EEPROM or Flash
Storage Capacity
2 million readings
Logging Lifetime
Typically over one year, depending on logging regime
 
AQUAlogger 210 General Specification
 
Acquisition System
8 channel 16-bit
Inputs
2 channels 0-5V buffered; 6 channels 0-2.5V
Controls
Digital outputs to control external gain setting, etc
Communication
USB 1.1 (no power required) and RS232 or RS485
Burst Sampling
Bursts every 1 - 255 seconds or 1 - 255 minutes
Within-Burst Rate
From 1 Hz to once every 30 seconds
Burst Averaging
Bursts may be averaged to a single data value
Data Storage
Non-volatile FLASH
Storage Capacity
Nominal 2M sets ¸ number of channels enabled.
Data Retention
>10 years
Logging Lifetime
Typically 1 year
Battery
3 x 3.6V Lithium 'AA' Cell - User replaceable
Software
AQUAtalk for Windows for configuration and download or DLL for inclusion in host applications
Dimensions
300 mm (11.8") long x 60 mm (2.4") diameter
Weight
1100 g (39 oz) in air; 460 g (16 oz) in water
Attachment
Single point attachment through mounting hole
Maximum depth
1000 m standard, deeper versions on request
 
AQUAlogger 210TYT Sensor Specifications

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.

 
Light Source Wavelength
880 nm
Scatterance Angles
15 - 150 degrees
Linearity
<2% deviation 0 - 750 FTU
Measurement Range
0.01 FTU to >750 FTU over four automatically switched gain ranges. Above 750 FTU the sensor is non-linear.
Operating Temperature
0ºC to 50ºC
Dimensions (exc connector)
225mm (8.9") long x 70mm (2.8") diameter
Temperature
Sensor Type
Thermistor
Ranges
-2-30°C standard, other ranges on request
Resolution
better than 0.0015°C
Accuracy
±0.05°C
Time Constant
max 5 seconds
 
 
 
 
 
 
 

 

 

 

 

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:

 

  

More information about Vilanova turbidimeter here.

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