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Sequoia is the sole manufacturer
of the LISST series laser particle size analyzers. The array of
instruments originated with applications in the marine environment, but
now includes diverse fields such as stream-gaging, paper emulsifier optimzation, airborne cloud dropet measurements and others still in development. Some of these instruments
deliver the optical volume scattering function
(VSF) of interest to optical oceanographers.
The LISST series includes submersible and non-submersible instruments. All
employ the small-angle forward scattering principle, also called low-angle laser
scattering or laser diffraction.
The submersible series includes:
- LISST-100X
- LISST-FLOC
- LISST-DEEP
- LISST-ST
- LISST-25X
- LISST-SL
Of these, the LISST-100X is our workhorse. It delivers the
size distribution of suspended sediments in 32 logarithmically spaced size
classes. Different models of this instrument cover different rnage of sizes.
The LISST-FLOC covers the largest sizes,
7.5 to 1500 microns (nominal), and is intended for measuring flocculated marine
particles. These instruments can be used as laboratory instruments, with
provided accessories. The LISST-Portable (see below) is a portable version which can be
driven to a site (river, stream, highway runoff..) or carried on an airplane.
LISST-Deep is a deep version capable of
operations to 6000m.
The LISST-ST
is an extended version of the LISST-100X, with an added Settling Tube (ST stands
for Settling Tube). This instrument is designed to perform submerged settling
experiments to obtain settling velocities of 8 size classes. With the settling
column removed, the LISST-ST may be used as a -100X, but with less than optimal
flow through the sample volume.
The LISST-25X is a patented derivative product. It
delivers the suspended sediment concentration and mean size in two size classes
(2.5-63 and 63-500 microns).
All of the above submersible instruments
incorporate a depth sensor. They are powered by internal batteries and store
data internally.
The LISST-SL is
an isokinetic version of the LISST-100X developed for river sediment monitoring.
It senses river velocity and adjusts intake velocity to match. Optics and
electronics are enclosed. Data are stored on a bridge-top Topside box.
Field and Portable Particle/Sediment Size Analyzers
- The LISST-Portable
- LISST-StreamSide
- LISST-Infinite
The LISST-Portable is a field or laboratory device for particle size and
concentration measurements. It is also battery operated, easily
transported (car, airplane), and autonomous. Data are stored on
board.
The LISST-StreamSide is meant for use in shallow streams or
rivers and is designed for applications where bio-fouling is
an issue, or streams are too shallow for instrument submergence,
or there exist concerns regarding the safety of the equipment from
flowing debris or due to vandalism. The instrument is designed to be
enclosed in a shed, wth power provided. A pump is inserted in the
stream to deliver water. This device displays the size distribution in
real time on a plasma display and stores processed data for subsequent download.
Deliveries are planned for mid-2007.
The LISST-Infinite is designed for measuring very high concentrations
of sediment, such as occur in rivers or in run-of-river Hydro power plants. The instrument is placed in a
shed and again, water is pumped through it. A clean water source is
required for dilution. The instrument performas dilutions if needed.
For more information on these instruments, please click on the links at top of this page, or contact us.
A LISST for Emulsifier Optimization in the Paper Industry
The LISST-EO
is an in-line process control tool. It is designed to measure particles
in the 0.3-60 microns( nominal size). This device employs our standard
forward low-angle scattering technology with the reverse Fourier
geometry. The instrument displays the size distribution on a
panel-mounted plasma display, and sends the data to a remote desk for
display and storage. Deliveries are planned for mid-2007.
A LISST-Wing for measurement of Cloud Droplet Size Distributions
This instrument
was designed for use from research aircraft for studies of cloud
droplet processes. It employs the standard forward scatter laser
technology of all our instruments. It too records data internally
and/or transmits the data over a serial line to the aircraft cabin. The
instrument is currently undergoing testing for survival in wind-tunnel
environments. For further information, please contact us.
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|  | | LISST-Portable re-design |  | | Sequoia's LISST-Portable is undergoing a re-design in order to be equipped with a touch panel display similar to the one on the LISST-StreamSide. Also, all dataprocessing will now take place on-board in real-time so no data post-processing is necessary. The first units will ship in October 2008. | |  | |  | | | |
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