User Manual

<Appendix 2 For SC (Conductivity)>
App.2-9
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
n Temperature compensation error
The temperature compensation error (alarm) is issued in any of the following cases.
l TC
The error is issued when:
(measuredtemperature–referencetemperature)<–90/compensationcoefcient
Thedefaultofthetemperaturecompensationcoefcientis2.10%/°C.
Forexample,whenthereferencetemperatureis25°C,thetemperaturecompensationcoefcient
is 2.10%/°C and the measured temperature is lower than –17.9°C, the error will be issued.
Temperature compensation is performed even while an alarm is being issued.
l Matrix
The error is issued when the temperature or the precompensated conductivity is out of the range
ofthetemperaturecompensationmatrix.
Inthiscase,however,thetemperaturecompensationisperformedbyextrapolationevenwhile
an alarm is being issued.
l All
When the conductivity is around zero, the temperature compensation error may be issued. In this
case, the temperature compensation is not performed, and the precompensated conductivity is
displayed.
Whether the conductivity is around zero or not is determined by the temperature and conductivity
ofsolutions.Forexample,whenthetemperatureis20°Candtheconductivityislowerthan0.033
μS/cm,theconductivityisdeterminedtobearoundzero.
When measuring the conductivity around zero in air calibration or when the conductivity to be
measured is around zero, an alarm may be issued.
NOTE
Todisplaytheprecompensatedconductivity,settheMethodto“None”.
SelectMeasurementsetup→Temp.compensation.
n TDS readings
TheconceptofTotalDissolvedSolids(TDS)iswidelyusedasanindicationofthetotalsolute
concentrationinwaterandisawidelyacceptedwaterqualitystandard.Thedeterminationis
simply made by evaporation and weighing the residue. As the heat treatment converts the
chemical properties of the solution, some solutes that contribute to the total conductivity will not
be found in the residue. Also some combinations of solutes will become volatile at the drying
temperature. The same applies for those solutes that do not contribute to the conductivity but do
end up in the residue. When one (or a few) solute is dominant in the solution, these problems
maybeneglectedandTDSwillhaveadirectcorrelationwiththeconductivity.
Nextisagraphthatshowsthecorrelationbetweenthespecicconductanceandconcentrations
(byweight)forsixsalts.Thefactorbywhichtheconductivityshouldbemultipliedtocometo
aTDSreadingrangesfrom0.4to0.7uptoaconductivityof500µS/cm.Ataconductanceof
approximately3000µS/cmtherangewouldbefrom0.5and1.0.
TheFLXA21measuresconductivity.ThisvaluecanbeusedtodisplayTDSvaluesonthemain
display.Oneshouldusetheadditionalconcentrationtable.TheunitfortheTDSreadingcanbe
set to ppm or ppb.
App.
SC