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Instrument Statistics: Click here for Malvern's Mastersizer 2000 website. The schematic to the right was taken from that site. Click on the image for a larger version of it. |
Malvern Mastersizer 2000 Laser Diffraction Grain Size Analyzer
What it does: The Malvern Laser Diffraction system uses pulses of red and blue laser light sent through an emulsion of sediment and water to measure the grain size distribution of the particles. 
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How it works:
Sediment samples are prepared for analysis on the
Malvern Mastersizer by separating grains greater than 1 mm using a #18 sieve. The larger size
fraction is analyzed separately using a standard set of sieves. Before and after this
separation, the sample is weighed and the weights of the size fractions are recorded. The less
than 1 mm fraction is then prepared for Mastersizer analysis by mixing it with distilled water and
a Calgon solution that minimizes grain clumping, or flocculation. This water-sediment emulsion is
added to a circulating water flow in an attached Hydro S sample dispersion unit that sends the emulsion
through a glass-walled chamber in the Mastersizer.
The Mastersizer operates by sending laser pulses through the emulsion as it flows through the glass-walled chamber. The pulses are diffracted by the sediment grains in the emulsion and then are detected by a series of photovoltaic sensors that are arrayed at varying distances from the window. |
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Larger particles diffract light at greater angles and
therefore, the light from these is detected by sensors closer to the window. Smaller particles
diffract light at lower angles so these pulses are detected by more distant sensors.
Counts from the sensors are tallied, averaged and reported as a grain-size distribution. Grains from
1 mm to 0.001 mm in diameter can be detected. Analyses are repeatable to ±0.5%, and a
sample can be analyzed in 5-10 minutes, versus many hours or days using older techniques.
Last updated 12/10 |
Image from: www.malvern.com |
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