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Sequoia Scientific

LISST-SL2

Isokinetic River Sediment Monitoring

The LISST-SL2 is a our most powerful multi-parameter river sediment monitoring instrument. The -SL2 is an advanced version of the original -SL. 

The streamlined body is a minimum drag shape. A pitot static tube on top of the body measures river velocity. Twin fins below the body orient the LISST-SL2 facing upstream just before immersion.

The system employs active control of an intake pump that matches intake velocity to river velocity, making the sample acquisition isokinetic. Diffracted light is measured in the included electro-optics mid-section. [The features section below lists new features.]

 

Updated 24 August 2017

Features

  • The LISST-SL2 has a greatly simplified user interface compared to the original LISST-SL.
  • Uses laser diffraction; new: redesigned optics cover expanded grain size range, 1-500 microns (from 2-386 microns for LISST-SL)
  • Isokinetic; new: advanced pump control.
  • 2-wire special communication protocol consistent with USGS B-reel use.
  • Topside Box (TCB) contains batteries, and transfers data to laptop computer using blue tooth.
  • Display on computer shows battery life remaining, and issues warning when low.
  • Real-time display: Current speed, temperature, concentration, grain size distribution, depth, mean sediment grain size.
  • New: software delivers point-integrated and depth-integrated sediment data.
  • Blue-tooth data link permits operation out of weather.
  • Switch between ft and ft/s or m and m/s for depth and velocity units.
  • Real-time data processing permits time-series or vertical profile format for all data.
  • Easier storage and maintenance after use.

A major difference between the LISST-SL2 and other LISST instruments is that the LISST-SL2 is only a sensor. It cannot operate autonomously and no data can be stored on the instrument itself. The LISST-SL2 must be  connected using a USGS B-Reel to a Topside Control Box (TCB). The TCB contains a rechargeable battery and electronics. It supplies power down the B-Reel cable to the LISST-SL2, and receives the raw scattering data from the LISST-SL2. These data are transmitted via blue-tooth to a nearby laptop, or tablet (Windows only). Using the computing power of the laptop, raw data are processed on the laptop in real-time, and all results are displayed [e.g. optical transmission, velocity, depth, temperature, particle size distribution, total concentration…]. The operator can choose time-series view, or vertical profile view. Post processing software generates point-integrated or depth-integrated concentrations – thus providing data that has historically been collected laboriously with bottle samplers. In addition, when concentrations are combined with velocity data, sediment flux (transport rate) is also obtained. The data are so rich that interested scientists may easily obtain flux of particles in 36 distinct size classes!

All data, raw and processed, are output in user-friendly formats.

 

 

Specifications

Specifications are subject to change without notice

Sediment Concentration Range

  • Range: 15 – 13,500 mg l-1 for standard 3.2 mm optical path. NOTE: THE ACTUAL CONCENTRATION RANGE IS STRONGLY GRAIN-SIZE DEPENDENT.
  • Resolution: < 10 mg l-1.
    Material  SSC [mg/l] @ 98% optical transmission  SSC [mg/l] @ 30% optical transmission  D10[µm]  D50[µm]  D90[µm]  SMD[µm]
    ISO Fine
    (ISO 12103-1,A2)
     15 1,150 1.5 7 41 3
    ISO Coarse
    (ISO 12013-1,A4)
     67  2,500  4  38  99 10
    Whitehouse20-30 µm glass beads  130  7,400  19  24  34 24
    Sieved sand 75-125 µm  215  13,500  85  122  175 112

Size Range

  • 1-500 µm in 36 log-spaced size classes.

Depth Range

  • 0.15-30 m @ 0.02 m resolution.

Current Speed Range

  • 0-3 m/s @ 0.03 m/s resolution.

Water Temperature Range

  • 0-25C @ 0.1 C resolution.

Sample Acquisition Time

  • 2 seconds for a 16 sample average
  • Average value subsequently transmitted to the Topside Control Box for immediate display

Mechanical and Electrical

  • Dimensions (SL2): 17 cm (6.7”) maximum Ø × 87 cm (34.2”) L
  • Topside Box: 16.4″ (41.7cm) x 8.7″ (22.1cm) x 13.2″ (33.4 cm)
  • Weight in air / submerged (SL): 16 kg (35 lbs) / 7 kg (15.4 lbs)
  • Topside Box: 8.6 kg (19 lbs)
  • Rechargeable battery life: 6 hours (nominal; longer available)

Accessories

There are no available accessories for this instrument at this time

FAQ