【国外标准】 Standard Test Methods for Water in Engine Coolant Concentrate by the Karl Fischer Reagent Method

5.1 The total apparent water in engine coolant concentrate as determined by Karl Fischer titrations consists of the following: (1) water present in the original glycol base; (2) water added (for example, inhibitor solutions); (3) water of hydration of inhibitors (for example, Na2B4O7·5H2O); (4) water formed in the chemical reaction between borate and ethylene glycol, producing boratediol condensate and water; and (5) quantitative interference by the reaction of the reagent with inhibitors such as tetraborate or sodium hydroxide.1.1 These test methods cover the determination of the water present in new or unused glycol-based coolant concentrates using a volumetric (Test Method A) or an automatic coulometric titrator procedure (Test Method B).1.2 Many carbonyl compounds react slowly with the Fischer reagent, causing a fading end point and leading to high results. A modified Fischer reagent procedure is included that minimizes these undesirable and interfering reactions.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements see Sections 8 and 16.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.