IEC 60746-2:2003 pdf free download

IEC 60746-2:2003 pdf free download Expression of performance of electrochemical analyzers – Part 2: pH value
5 Recommended standard values and ranges of influence quantities affecting the performance of electronic units See Annex A of IEC 60746-1 .
6 Verification of values See Clause 6 of IEC 6046-1 , plus the following:
6.1 General aspects
6.1 .1 Glass electrodes shall be conditioned according to the manufacturer’s instructions. At least 1 2 h hydration in a neutral or mildly acidic buffer solution shall be allowed for initial equilibration of new electrodes.
6.1 .2 Reference pH buffer solutions shall be used for all tests unless otherwise agreed upon with the manufacturer (see 3.5 of IEC 60746-1 and Annex B) . NOTE IUPAC recommended reference buffer solutions are tabulated in Annex B. Other reference pH buffer solutions may be used .
6.1 .3 Test solutions shall be applied in a manner suited to the sensor unit.
6.1 .3.1 Flow-through sensor units Solutions shall be applied at a flow rate within the manufacturer’s rated range.
6.1 .3.2 Insertion sensor units For measurements with more than one solution, unless otherwise indicated, the electrode pair (sensor unit) shall be rinsed with deionized water, thereafter pre-rinsing with the new solution prior to immersion. It is recommended that measurements shall be made in continuously stirred solutions to ensure homogeneity.
6.2 Test procedures for electronic units Prior to testing the analyzer, the electronic unit shall be separately tested with a simulator such as that described in 3.1 .1 2 and using either manual temperature control or a suitable resistor connected to the temperature compensator input.
6.2.1 pH scaling If adjustable, set the isopotential control to the zero point pH, usually both are pH 7, and, if provided, cancel or adjust the sample pH temperature compensation to zero. If manually adjustable, set the percentage slope control to 1 00%. Adjust the manual or simulated temperature to 25°C or other reference temperature. Connect a simulator and check the scaling throughout pH 0 to pH 1 4 or the test pH range. At the scale length extremes, switch-in the series high resistance simulating that of the glass electrode as a check of the instrument’s input impedance, an immediate transient should rapidly dissipate. Repeat the procedure for other temperatures within the test range (see Table A.1 ). With the simulator, impose a lower percentage slope output (for example, at 25 °C for 90 % slope, 53,24 mV per pH unit) at 25 °C or other reference temperature to assess the percentage slope facility.
6.2.2 Isopotential pH, pH i The electrode terminals, including solution earth if applicable, are shorted and the temperature set to 25°C, either manually or with a suitable variable resistance 1 . The display will indicate the zero point, usually pH 7 and identical to the isopotential pH, pH i . Change the temperature setting from 0° to 50°C, ideally there will be no display variation.