NIVELCO AnaCONT LE-100 Installation And Programming Manual

NIVELCO AnaCONT LE-100 Installation And Programming Manual Manual pdf 25 page image

BKI 11 ATEX 0012 X le00100a0600p_05 25 / 604.2.2. Verification of the ORP electrodeThe calibration can be done (for example) with a 465 mV buffer solution. After the electrode is rinsed with distilled water put the electrode into the buffer solution. Theelectrode should reach the correct measurement value in 30 seconds. If the measured value is less with more than (the acceptable) 20mV the electrode should becleaned. If the electrode does not give the desired measurement after cleaning it has to be replacedRecommended solutions:ORDER C ODE D ENOMINATION4vpuf22050mor Buffer solution ORP 220 mV / 50 ml4vpuf220100or Buffer solution ORP 220 mV / 1 l4vpuf46550mor Buffer solution ORP 465 mV / 50 ml4vpuf465250or Buffer solution ORP 465 mV / 250 ml4vpuf465100or Buffer solution ORP 465 mV / 1 l4vtarkcI 350ph Storage solution KCl 3 mol / 50 ml4vtarkcl 250ph Storage solution KCl 3 mol / 250 ml4vtarkcl 310ph Storage solution KCl 3 mol / 1 l4vtiszold 25ph Cleaning solution / 250 mlThe given (mV) values refer to 25°C. The temperature dependency is given by the manufacturer, usually in a table on the label of the bottle.4.2.3. Periodic calibration of the DO sensorThe calibration has to be done minimum in two measuring points. Calibration points should be selected according to the required range to cover almost or fully.In every case it is necessary for the calibration: one solution which does not contain any oxygen – may be a neutral gas – for the zero standard calibration, and another solution which has a known oxygen concentration for the full-scale standard calibration.Zero calibration is necessary, because DO sensor gives output current when the measured medium does not contain any dissolved oxygen. This current is calledresidual-current. The required zero-standard is an aqueous solution of sodium-sulphite (Na 2S0 3) and cobalt(II)-chloride hexahydrate (CoCl2-6H 2O) preparedaccording to the followings. Oxygen-free nitrogen gas can be also used as zero-standard. The zero point calibration determines the offset of the calibration line.Required items: 1 clean pot 1 mixer 1 dl distilled water 1g sodium-sulphite (Na 2S0 3) 1mg cobalt(II)-chloride hexahydrate –Analytical Reagent– (CoCl 2-6H 2O)