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LISST Instruments > LISST-25X - an advanced turbidity sensor
| LISST-25X | | | | | | |

  The LISST-25X can be rented. The minimum rental period is one (1) month.  Please contact Sequoia for more information about rental price, terms and conditions etc. 
    

 LISST-25X marks a generational advance in the measurement of suspended sediments. Unlike all prior sediment or turbidity sensors, optical or acoustic, the LISST-25X maintains its calibration over a 200:1 range of particle sizes.  This is the only sensor capable of holding calibration for sediment concentration regardless of particle color or size within this broad a range.  Depending on grain size, the LISST-25X is suitable for operations in an approximate concentration range of 1 to 2000 mg/l.

Essentially, the LISST-25X offers capabilities between those of an OBS, which suffers calibration changes due to changes in grain size or color and the LISST-100X, which provides the detailed size distribution. In short: The LISST-25X overcomes the OBS’s shortcomings, but does not provide the full size distribution of the LISST-100X. 
 
    

 An anti-fouling accessory BioBlock is available for this instrument (see LISST accessories page).  The picture on the left shows the LISST25X with the BioBlock installed.

BioBlock is very strongly recommended for deployments in biologically productive waters.
 
  
 

 The instrument is self-contained, with memory and batteries. It is fully programmable to set sample rate. Data can be internally stored or captured in real time.  A depth sensor is included as standard. Windows software for data offload and display is provided. 
    
  The idea behind the LISST-25X is to use shaped focal plane detectors. These detectors (see figure) derive their shape from the physics of light scattering. The shape is found such that for any size of particle in the 2.5 to 500 micron range, the instrument reports the correct volume concentration. A different shape is found to yield area concentration.The ratio of volume to area is called the Sauter Mean Diameter. The instrument employs 2 pairs of shaped detectors. One pair measures particles in the 2.5 to 63 micron range, the other in the 63-500 micron range.
 
    
 

Related Links
Publications
>Library (general list of publications)
>Agrawal & Mikkelsen (2009) - free .pdf
>Topping et al. (2006) - free .pdf
 
User's Guide
>LISST-25X Manual Version 1.30

Technical Specifications
>.pdf format
>HTML format
 
Related Products:     
>LISST-100X
    
  Updated 2/16/2011.
 
Sequoia visit to Colombia and Ecuador!
Sequoia's Yogi Agrawal and Ole Mikkelsen visited C'Particulas, Sequoia's Colombian distributor 28-30 November 2011. See the pictures on our facebook page!
Association Of Environmental & Engineering Geologists 54th Annual Meeting
Anchorage, AK, 19-23 September 2011, booth 31

CASQA 2011
Monterey, CA, 26-28 September 2011, booth 41


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