Water hardness determn. - using tablets contg. sodium or potassium EDTA salt, indicator, pelletiser, decomposer and filler

摘要

A graduated measuring vessel issued, having vol. 100-300(150-250) ml., in combination with tablet(s), weighing 0.2-5g. Tablets contain, by wt., (a) 1-30(2-10)% EDTA tetra Na or K salt, (b) 0.002-1% indicator and (c) 69-98.998% standard pelletising additives, tablet decompsn. auxiliaries and fillers, which dissolve in water without causing cloudiness. The tablets are dissolved in a small amt. of the water to be treated, then more water to be tested is added until colour-change takes place. Process is used for measuring wash water hardness and enables an unskilled user to determine optimum amt. of necessary detergent. In an example, mixt. of 5% Na ethylene-diaminotetraacetate, 88.5% lactose, 0.5% Mg stearate, 3% microcrystalline cellulose, 0.02% indicator, 2.18% NaCl, was pressed to 1.5g. tablets, having thickness 3.5 mm., dia. 20 mm.