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[March 2002]
Extreme Tests for Autosampler at Guiraud Freres
The new Autosampler for the Mastersizer 2000 laser diffraction based particle size analyser has been subjected to an extreme measurement test in the laboratories of Terreal Guiraud Freres, a France based subsidiary of St Gobain.A key function of any autosampler for particle sizing, says Mastersizer's manufacturer Malvern Instruments Ltd (Malvern, Worcs, England), is the ability to perform measurements with consistency and produce results that are in absolute agreement with the best efforts of a skilled operator.
Accurate sampling of large particles is especially important and is often a very challenging task for an autosampler. The importance of meeting this challenge, adds the company, can be appreciated when it is realised that - in terms of volume - a single 100-micron particle is equivalent to a million 1-micron particles. If the largest material is sampled incorrectly, the resultant errors can have a severe impact on the measurements obtained and the decisions based on these measurements.
Tests at Terreal Guiraud Freres involved the use of a sample that contained particles with a size distribution from 0.4 microns to more than 2000 microns. To carry out these tests, samples were very carefully split using a spinning riffler to ensure that each sample was as representative of the bulk as possible.
A reference set of data was produced by loading a series of samples by hand and measuring them. A further set of measurements was then made by using the Malvern Autosampler. Overplots of the two sets of measurements indicate that the Autosampler delivered these difficult samples to the sizer with exactly the same accuracy as was obtained by the experienced operator.
Following the successful conclusion of these and other equally searching tests, the Autosampler 2000 has been retained by Terreal Guiraud Freres to help them maintain the quality of their range of building materials.
ENDS