Method and apparatus for the determination of the water hardness

摘要

The hardness of water is determined by (a) measuring the conductivity of the water; (b) subjecting the water to ion exchange to convert hardness ions to conductive ions; (c) measuring the conductivity again; and (d) calculating the hardness from the difference between the two conductivity measurements. Pref., water in a pipe (1) is sampled by means of a branch pipe (2) with a magnetic valve (3). The conductivity is measured with a pair of electrodes (11,12) connected to a conductivity meter (18). The sample is then passed through a column contg. an upper bed (6) of strongly acidic cation exchanger in Na form (to convert Ca(2+) and Mg(2+) and a lower bed (7) of anion exchanger in OH form (to convert HCO3(-) and Cl(-) to OH(-). The conductivity of the column effluent is measured with another pair of electrodes (15,16) connected to the meter. ADVANTAGE - The method is simple, can be performed rapidly and is easily automated.