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From time to time, Sequoia will update the US and other International Standards known to us, that relate to our products.
We invite visitors to our website to send us information on relevant standards that they feel need to be included on this page. |
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| Laser Diffraction Standards |
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| ISO-13320:2009 |
ISO standard describing the laser diffraction method. |
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| ASTM B822-10 |
ASTM standard describing the laser diffraction method. |
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| ASTM D4464 |
ASTM standard describing the laser diffraction method. |
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| Turbidity Standards |
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| ISO-7027:1999 |
This is a turbidity standard, reporting results in FNU (Formazin Nephelometric Units). It is based on monochromatic light scattering at 90-degrees plus or minus 2.5-degrees. Like the USEPA turbidity standard below, this standard has no relationship to suspended sediment mass or volume. The conversion to suspended sediment concentration changes with changes in sediment grain size, color, ligth wavelength, and particle shape. For more details, we recommend visiting http://www.omega.com/techref/ph-6.html. |
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| US EPA 180.1 |
This is the US version of the ISO standard mentioned above. The results are reported in NTU (Nephelometric Turbidity Units), again with Formazin as the standard. This method, unlike ISO-7027, this standard is more lax (and therefore, even less reliable). The scattering angle can be 90 +/- 20-degrees. The lamp need not be monochromatic, etc. Fundamentally, this method suffers from all the ills of the ISO method. |
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| Drinking Water Standards |
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| EPA |
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| Standard Particles |
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Polystyrene spheres
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For extremely precisely sized polystyrene spheres, go to http://www.dukescientific.com/ |
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Glass beads
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To obtain Glass Microspheres for laboratory calibrations, visit http://www.whitehousescientific.com. Sequoia uses the following Whitehouse Glass Microspheres for validation: |
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ISO-12103-1:1997
(AZ test dust)
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To obtain natural particle standards of Arizona Test Dust, also called AC Spark Plug Powder, contact Powder Technology Inc. These particles are also used as a standard by USGS. Sequoia uses the following Arizona Test Dust Nominal Sizes for validation:
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| Turbidity Standards |
To obtain Turbidity Standards in NTU units, visit http://www.voigtglobal.com/turbidity.htm |
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| Updated 10/7/2011 |
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|  | | Sequoia visit to Colombia and Ecuador! |  | | Sequoia's Yogi Agrawal and Ole Mikkelsen visited C'Particulas, Sequoia's Colombian distributor 28-30 November 2011. See the pictures on our facebook page! | |  | |  | |
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