Principal scientist, Research Center, The Foxboro Co., Burlington, Mass.
director, Research and Development, Vaponics, Inc., Plymouth, Mass.
Pages: 10 Published: Jan 1981
Theoretical calculations have been made for the resistivity (and its reciprocal, the conductivity) of pure water in the vicinity of the neutral point at 25°C. A surprising result is that the maximum resistivity is not found at pH 6.998, which corresponds to absolute water, but at pH 7.039, which corresponds to water with approximately 0.8 μg/litre, (parts per billion) of sodium hydroxide added. The resistivities corresponding to these two points are 18.18 and 18.28 MΘ · cm respectively. Although the effect is slight, it will be of interest to users of high-purity water since resistivity is widely used as a criterion for water purity. The temperature coefficient of resistivity is also evaluated.
resistivity, power plants, conductivity, water, temperature coefficient, instrumentation, water quality
Paper ID: STP28286S