What is "nephelometer"

Nephelometer \Neph`e*lom"e*ter\ (n[e^]f`[-e]*l[o^]m"[-e]*t[~e]r), n. [Gr. nefe`lh a cloud + -meter.]

1. An instrument for measuring or registering the amount of cloudiness.

2. (Chem., Microbiol.) An instrument which measures the degree to which liquid suspensions scatter light, and by inference, the concentration of scattering particles in the suspension. It is used for various purposes, such as to estimate the number of bacteria in suspension in a liquid.

n. (context analytical chemistry English) An instrument for measuring various aspects of the suspended particles in a fluid; especially in a colloid.

A nephelometer is an instrument for measuring concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam (source beam) and a light detector set to one side (often 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 particles is dependent upon properties of the particles such as their shape, color, and reflectivity. Nephelometers are calibrated to a known particulate, then use environmental factors (k-factors) to compensate lighter or darker colored dusts accordingly. K-factor is determined by the user by running the nephelometer next to an air sampling pump and comparing results. There is a wide variety of research-grade nephelometers on the market as well as open source varieties.