a)ATCmode:Puttheselectionknobon “”.Thevalue displayedmeansthetemperatureofthe
mediumtobemeasured.At thesametimethe temperaturesignalbesenttothepH-t mixturecircuit
tocompensatethe pHvalue.
b)MTCmode:Removethe temperaturesensor,Putthe selectionknobonMTCand “”position.
Adjustthe temperatureregulation knobuntil the value oftemperaturedisplayed issameasthe
indication value ofthermometerpluged inthe mediumtobemeasured.Atthesametimethe
temperaturesignalbesent tothepH-tmixturecircuittocompensatethe pHvalue manualy.
2.3Calibration
Beforeoperating,i.e.beforemeasuringthe solution tobemeasured,the instrumentshouldbe
calibrated.However,itdoesnotmean thatitmustbecalibrated beforeoperatingeachtime.For
successiveoperating, ingeneral, it will becalibrated onceaday.
Therearetwomethodsofcalibration,one isone pointcalibration fornormaluseand the otheristwo
pointscalibration forexactmeasuring.
2.3.1 One point calibration procedure(takingATCforexample):
a)Removethe Q9shortcircuitplug,Linkthecompound electrodeandthetemperaturesensor,clean
the electrodewithdistilled waterand blotitwithfilterpaper,then plugtheelectrodeintothebuffer
solution (pH=4orpH=9.18).Tomeasurethe temperaturefirst, putthe selection knobon “”and
ATCposition,The value displayedmeansthe temperatureofthe mediumtobemeasured.
b)Putthe selectionknobon “pH”,turnthe slopeknobtothe end clockwise,adjustsettingregulator
until the value displayedequalstothestandardpH(pH=4orpH=9.18).
Note:The setting”knob will notbechangedaftercalibration finished.
2.3.2 Twopointscalibration procedure:
a)TakingATCforexample.Removethe Q9shortcircuitplug,Linkthecompound electrodeandthe
temperaturesensor,clean the electrode withdistilled waterand blotit withfilterpaper,then plugthe
electrode intothe buffersolution (pH=6.86).Tomeasurethe temperaturefirst, putthe selection knob
on “pH”,The value displayedmeansthe pHofthe standardbuffersolution (pH=7).
b)Ifthe solutiontobemeasured isacidic,takeoutthe electrode fromthe solution ofknownpHvalue
(pHvalue =6.86),clean theelectrodewithdistilled waterandblotitwithfilterpaper,then plugitinto
the buffersolution ofknownpHvalue (pHvalue =4).Adjustthesloperegulatoruntil thevalue
displayed meansthe pHofthe standardbuffersolution (pH=4).
c)Ifthe solutiontobemeasured isalkalescent, wecancalibratethe metersecondlywiththe solution
of knownpHvalue (pHvalue =9.18).Adjustthesloperegulatoruntil thevalue displayedmeansthe
pHofthe standardbuffersolution (pH=9.18).
Thecalibration ofthe instrumentiscompleted.Oncetheinstrumenthasbeencalibrated,itsSETTING
potentiometershouldnotbechanged anymore.
2.3.3 Calibration withMTCtoreference2.2(b).
3. pHvaluemeasurement
a)Incasethatthetemperatureofthesolutiontobemeasured thesameasthetemperatureofthe
settingsolution.
Rinsethe endofthe electrodewithdistilled water,andsuck itdrywithclean filteringpaper.Putthe
