A nephelometer is an instrument for measuring suspended particulates in a liquid. It does so by employing a light beam (source beam) and a light detector set to one side (usually 90°) of the source beam. Particle density is then a function of the light reflected into the detector from the particles. To some extent, how much light reflects for a given density of particules is dependent upon properties of the particles such as their shape, color, and reflectivity. Therefore, establishing a working correlation between turbidity and suspended solids (a more useful, but typically more difficult quantification of particulates) must be established independently for each situation. Flour suspended in water In chemistry, a suspension is a dispersion (mixture) in which a finely-divided species is combined with another species, with the former being so finely divided and mixed that it doesnt rapidly settle out. ... A liquid will assume the shape of its container. ... In general, something that reacts to stimuli in a set manner, and is either part of a living being, or made by a living being, for the purpose of doing such reacting. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... The word reflection (also spelt reflexion in British English) can refer to several different concepts: In mathematics, reflection is the transformation of a space. ... Total suspended solids is a water quality measurement usually abbreviated TSS. This parameter used to be called non-filterable residue (NFR), a term that refers to the identical measurement: the dry-weight of particles trapped by a filter. ...

A more popular term for this instrument in water quality testing is a turbidimeter. However, there can be differences between models of turbidimeters, depending upon the arrangement (geometry) of the source beam and the detector. A nephelometric turbidimeter always monitors light reflected off the particles and not attenuation due to cloudiness. The units of turbidity from a calibrated nephelometer are called Nephelometric Turbidity Units (NTU). Geometry (from the Greek words Geo = earth and metro = measure) is the branch of mathematics first popularized in ancient Greek culture by Thales (circa 624-547 BC) dealing with spatial relationships. ... Attenuation is the decrease of the amount, force, magnitude, or value of something. ...

See also: turbidity, water purification Turbidity standards of 10, 100, and 1000 NTU Turbidity is a cloudiness or haziness of water (or other liquid) caused by individual particles that are too small to be seen without magnification, thus being much like smoke in air. ... Water purification, or drinking water treatment, is the process of removing contaminants from surface water or groundwater to make it safe and palatable for human consumption. ...