IEC 60746-4:2018 pdf download

IEC 60746-4:2018 pdf download.Expression of performance of electrochemical analyzers
1 Scope
This part of IEC 60746 is intended: • to specify terminology, definitions and requirements for statements by manufacturers for analyzers, sensor units and electronic units used for the determination of dissolved oxygen partial pressure or concentration; • to establish performance tests for such analyzers, sensor units and electronic units; • to provide basic documents to support the applications of quality assurance standards [1 ] 1 . This document applies to analyzers using membrane covered amperometric sensors. It applies to analyzers suitable for use in water containing liquids, ultrapure waters, fresh or potable water, sea water or other aqueous solutions, industrial or municipal waste water from water bodies (e.g. lakes, rivers, estuaries), as well as for industrial process streams and process liquids. Whilst in principle amperometric oxygen-analyzers are applicable in gaseous phases, the expression of performance in the gas phase is outside the scope of this document. This document is applicable to analyzers specified for permanent installation in any location (indoors or outdoors) using membrane-covered amperometric sensors.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60746-1 :2003, Expression of performance of electrochemical analyzers – Part 1: General
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60746-1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Oxygen sensor properties
3.1.1 membrane covered amperometric sensor sensor with a membrane covered metal cathode, a metal or metal/metal salt anode, optional auxilliary or reference electrodes and temperature sensors Note 1 to entry: The electrochemical reduction of molecular oxygen occurs at the membrane-covered cathode. The metal or metal/metal salt anode provides a well-defined, electrochemically reversible oxidation reaction within the special filling electrolyte solution of the sensor. A gas-permeable membrane is employed to separate the electrolyte filling solution from the test medium to avoid contamination and to achieve a stable diffusion potential. In the case of applications in the gaseous phase the unit, volume fraction (v/v) are used. Note 2 to entry: The cell can function as an electrochemical two-electrode cell, or as a potentiostatic three- electrode cell, or either as a galvanic cell. Within potentiostatic three-electrode cells, a high-impedance, current- free reference electrode is additionally implied to optimize the polarization voltage. Note 3 to entry: Membrane-covered amperometric sensors are provided with temperature sensors located at the active sites of the electrode cells being in thermal contact with the media to be measured. 3.1.2 sensor sensitivity change in electrode current of the amperometric cell caused by the application of a partial pressure of oxygen 3.1.3 zero current of sensor current delivered by the sensor when the dissolved oxygen concentration or partial pressure is zero Note 1 to entry: The zero current is expressed in µA or in nA. 3.1.4 polarization voltage to be applied to an amperometric cell during a time period to increase the stability of the sensor 3.1 .5 stabilization time time period necessary for obtaining a stable measurement after reconnecting the sensor unit to the electronic unit for polarization purposes (see 3.1 .4) Note 1 to entry: Regeneration of the sensor with a new membrane or an electrolyte change or installation