Sequoia Scientific - Model LISST-100X Series - Measures Particle Size Distribution and Concentration; and Optical VSF
The LISST-100X instrument is a multi-parameter system for in-situ observations of particle size distribution and volume concentration. It also records the optical transmission, pressure and temperature. The instrument is fully self-contained with internal battery and data-logger.
- Small angle forward-scattering laser diffraction technology
- Self-contained with internal datalogger, CF memory module and alkaline battery pack
- RS232 connection to PC for real-time size distribution displays
- Programmable data collection
- Expandable CF memory module
- Integrated BioBlock connection
- Optional extra feature: Can be configured to receive input from Campbell OBS-3+, Turner Cyclops-7 or Sea-Bird Micro-Cat CTD.
Two size-ranges are available:1.25-250 microns (Type B) and 2.5-500 microns (Type C). Standard memory size is 128MB, suitable for storing approximately 1,600,000 size distributions, with option to expand to 1GB, or 12,800,000 size distributions. The depth range is 300 m, but a custom version (the LISST-DEEP) is available for deep-ocean environments (2500 m depth rating).
At the heart of the instrument is a collimated laser diode and a specially constructed annular ring detector (see Application Note L001). Scattering at 32 angles is the primary information that is recorded by the ring detector. This primary measurement is mathematically inverted to get the size distribution, and also scaled to obtain the volume scattering function (VSF). The size distribution is presented as concentration with units of micro-liters per liter (µl/l) in each of the 32 log-spaced size bins. Date and time, optical transmission, water depth and temperature are recorded as supporting measurements.
As an option, a modified endcap can be constructed, which makes it possible to connect either a Sea-Bird MicroCat CTD, a Campbell OBS 3+ or a Turner Designs Cyclops-7 fluorometer. Designed for extended field application, the LISST-100X is a self-contained battery-powered instrument that can be deployed on a tripod, used in a profiling mode, or moored. A range of accessories exists that makes it possible to use the LISST-100X as a laboratory particle sizer. A folded version and a short body version without internal battery also exists. The folded version is designed to fit in a Chelsea shuttle, while the short body version is designed for use with external power.
A large range of accessories has been developed for the LISST-100X, please view our accessories page for a detailed listing.
The LISST-100X and the LISST-Deep were both used intensively after the Deepwater Horizon accident in April 2010 to detect oil droplets and their size and concentration in the waters of the Gulf of Mexico. The EPA required the use of LISSTs for measurement of oil droplet size and concentration in the dispersed oil.
- Particle size distribution
- Particle volume concentration
- Volume scattering function
- Optical transmission
Sediment size distribution and scattering angles
- 32 log-spaced size classes
- 1.25 – 250 or 2.5 – 500 µm size range (equivalent to scattering at 0.08-15º or 0.04-7.5º in water, respectively)
- Range: 1 – 800 mg l -1 for standard 50 mm optical path (actual range depends on grain size )
- Resolution: < 1 mg l -1
- With a 50% PRM in place, all SSC values in the table above should be multiplied by 2.
- With an 80% PRM in place, all SSC values in the table above should be multiplied by 5.
- With a 90% PRM in place, all SSC values in the table above should be multiplied by 10.
- Solid state diode laser @ 670 nm, 1mW
- 32-ring custom photodiode detector
- Sample rate programmable, up to 25 Hz internally, 1Hz saving to data logger
- Optical path length @ 50 mm standard; bolt-on path reduction modules are available for higher concentration environments.
Mechanical and electrical
- Dimensions: 13.3 cm diameter x 87 cm long (5.25″ x 34.25″)
- Weight: 11 kg (25 lbs) in air; 3.6 kg (8 lbs) in water
- 300 m depth rating
- Serial interface: RS232C @ 9600 baud; high-speed offload at 115K baud
- Alkaline battery pack: Custom 9V nominal, 42 Ah
- External power input (optional): 12VDC nominal, 10-24VDC
- CF memory card: 128Mb standard (1,600,000 size distributions)
- Battery current drain: 146mA/8mA/128µA (measuring/quiescent/sleeping)