User Manual

<4. COMMISSIONING OF pH/ORP>
4-6
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
l Limits and timing
Zero High/Low
SetthehighandlowlimitsofZero(aspot).Duringcalibration,itischeckedwhetherthenewzero
exceedsthesehighandlowlimits.Narrowingthebandwillpreventbadcalibrationprocedures
and calibration of bad sensors, which results in higher accuracy. The default values should be
adjusted to suit the application and the “users” criterion.
Slope High/Low
SetthehighandlowlimitsofSlope(sensitivity).Duringcalibration,itischeckedwhetherthe
newslopeexceedsthesehighandlowlimits.Narrowingthebandwillpreventbadcalibration
procedures and calibration of bad sensors, which results in higher accuracy. The default values
should be adjusted to suit the application and the “users” criterion.
Step Range
Set the range over which the stability of a measured value is checked. If variations of a measured
value over the stabilization time are within this set value, the measured value is judged to have
stabilized.
Stabilization time
Duringcalibration,thestabilityofthepHvalueisconstantlymonitored.Whenvariationsofthe
pH value are within a value set in Step Range over this stabilization time set here, the value
is regarded as being stable. If the pH value does not stabilize within 10 minutes, calibration is
aborted.
Calibr. interval
Settheintervalinwhichanewcalibrationmusttakeplace.Iftheintervalsethereisexceeded,
theinstrumentwillbenotiedaccordingtothesettingin“Calib.timeexceeded”intheerror
conguration.
l Buffers (select set)
Calibrationismadeusingstandardcalibrationbuffers.WerecommendtheNIST(JISequivalent)
standardbuffersforhighestaccuracy,buttheuserisfreetoselectDIN19267,US,orauser-
denedbuffer.ThestandardbufferscanbefoundinAppendix1.
Threetypesofuser-denedbuffertablescanbedened.OntheFreeprogrammablescreen,
select a buffer table that you wish to set up. When a buffer table is selected on this screen, the
Buffertable1toBuffertable3screensoftheselectedbuffertablearedisplayed.
Clear table?
If you select “Yes” and press “Yes” when prompted to clear the table, the contents of the buffer
tablewillbecleared,thedisplaywillreturntotheBuffertablescreenautomatically,andthe“Table
was cleared” message will be displayed. If you want to perform temperature compensation using
thematrixafterclearingthetable,matrixvaluesmustberedened.
Check values?
If you select “Yes,” a value check starts. When the check ends, the results will be displayed on
thescreen.Whentheresultsarenormal,the“Noerror”messageappears.Incaseofanerror,
error information is displayed.
l Zero/Slope/ITP
You can enter Zero (aspot), Slope (sensitivity), and ITP values directly in the screen displayed.
These data can be obtained from the manufacturer of the probe, by the users laboratory, etc.
NOTE
It is not necessary to enter this data. In most cases, as the FLXA21 automatically does this while
performing calibration, the feature is used in the case of special electrode systems or where
calibration in the process environment is not possible. See Chapter 5.