標準號：IS 3025 Pt.21-1983
發布日期：1985/9/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：1.Prescribes two methods for determination of total hardness, namely:a) Ethylenediamine tetraacetic acetate acid ( EDTA) method, andb) Method based on analytical data.1.1 The first method is based on the reaction of calcium and magnesium salts with ethylenediamine tetra acetic acid or its disodium salt and is applicable to all types of water but not applicable to waste water. The analytical data method is based on computation from analytical results of the sample and is applicable to water and waste water. In case of dispute, the method based on analytical data shall be used.