A nephelometer[1] or aerosol photometer[2] is an instrument for measuring the 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.[clarification needed] There are a wide variety of research-grade nephelometers on the market as well as open source varieties.[3]
- ^ "Nephelometer" comes from the Greek word for "cloud", nephos, cf. "nepheloid layer".
- ^ Baron, Paul A. (1998-01-15). "Aerosol photometers for respirable dust measurements" (PDF). NIOSH Manual of Analytical Methods. Retrieved 2021-04-06.
- ^ Bas Wijnen, G. C. Anzalone and Joshua M. Pearce, Open-source mobile water quality testing platform. Journal of Water, Sanitation and Hygiene for Development, 4(3) pp. 532–537 (2014). doi:10.2166/washdev.2014.137 open access