Hanna Instruments HI 9828 Instruction Manual

Also see for HI 9828: Instruction manual

Hanna Instruments HI 9828 Instruction Manual Manual pdf 13 page image

131.5.3 pH and pH/ORP sensorsAs mentioned before HI 9828 is predisposed for pH andORP measurements.HI 769828PH and HI 769828PHO are probes with pHand pH/ORP sensors respectively. See the table below forelectrodes specifications.Reference Junction Electrolyte Tip Body materialpH double cloth gel spheric PEIO R P double cloth gel Pt PEITo avoid clogging problems and ensure a fast response, the pH bulb must bekept moist at any time. Store the electrode with few drops of HI 70300L storagesolution.To make correct redox measurements the following conditions must prevail:• The surface of the electrode must be cleaned and smooth.• The surface of the electrode must undergo a pretreatment in order to respondquickly.Because the Pt/PtO system depends on the pH, the pretreatment of the elec-trode may be determined by the pH and the redox potential values of the solutionto be measured.As a general rule, if the ORP mV reading corresponding to the pH value of thesolution is higher than the values in the table below, an oxidizing pretreatment isnecessary; otherwise a reducing pretreatment is necessary:pH mV pH mV pH mV pH mV pH mV pH mV0 990 1 920 2 860 3 800 4 740 5 6806 640 7 580 8 520 9 460 10 400 11 34012 280 13 220 14 160For reducing pretreatment: immerse the electrode for a few minutes in HI 7091L.For oxidizing pretreatment: immerse the electrode for a few minutes in HI 7092L.