User guide

53
IM 12D08N05-01E
A
APPENDICES
Appendix 4
Sensor selection for the EXAxt SC450G
Yokogawa supplies the following sensors, and their application is briefly described. All are compat-
iblewiththeEXAxtSC450G,andtheusermustbeawareofthesensorconfigurationfor2or4
electrodes, in order to set the converter correctly.
SC42-SP34 (&SX42-SX34) cc = 0.01 cm
-1
2-electrode sensor
Thissensoristhefirstchoiceforpureandultrapurewatermeasurements.From0.055µS/cmupto
100µS/cmthisisaperfectchoice.Themeasuringrangeextendstoatleast1000µS/cm,butthere
are better choices in that range.
Almostexclusivelyusedinflowfittingsandsub-assemblies.FF40andFS40.(The-SXsensorsare
screwed or flanged direct into the process pipework or tanks.)
SC4A-S(T)-XX-002...... cc = 0.02 cm
-1
2-electrode sensor
Thissensorisagoodchoiceforpureandultrapurewatermeasurements.From0.055µS/cmup
to 50µS/cmthisisagoodchoice.Themeasuringrangeextendsto500µS/cm,buttherearebetter
choicesinthatrange.The“SC4A-”sensorsmakeuparangethatusecompressionadaptersor
specialized fittings, including retractable.
SC42-SP24 (&SX42-SX24) cc = 0.1cm
-1
2-electrode sensor
Thissensorshouldbeusedforcleanandpurewatermeasurements.From0.2µS/cmupto1
mS/cmthesensorisfine,withmeasurementupto10mS/cmpossible,buttherearebetterchoices
inthatrange.Mountingofthesesensorsisasforthe....-SP(X)34series.
SC4A-S(T)-XX-010...... cc = 0.1 cm
-1
2-electrode sensor
Thissensorisagoodchoiceforcleanwatermeasurements.From0.5µS/cmupto200µS/cmthis
is a good choice. The measuring range extends to 2000µS/cm,buttherearebetterchoicesinthat
range.The“SC4A-”sensorsmakeuparangethatusescompressionadaptersorspecializedfit-
tings, including retractable.
SC42-EP15(D) cc = 1 cm
-1
2-electrode sensor
This sensor is intended as a handy, short sensor. It is easy to fit in a branch (tee) on a pipeline,
and is good for measurements where the precision is less critical than a convenient installation.
The D version is particularly suited to food applications because of it’s cleanability. Range of ap-
plicationisfrom10µS/cmto10mS/cm.
SC42-EP14 cc = 1 cm
-1
2-electrode sensor
Clean cooling and process water applications are where this sensor is used. The best range of ap-
plication is 10µS/cmto10mS/cm.ItisbettersuitedtoflowthroughinstallationsinFS40andFF40
adaptersandfittings,butitcanalsobeusedindiptubes-FD40.
SC42-EP18 cc = 1 cm
-1
4-electrode sensor
Cooling and process water applications are where this sensor is used, including light fouling. The
best range of application is 100µS/cmto100mS/cm.Thefour-electrodesystemcopeswithsome
contamination from the process, and eliminates the tendency for polarization to occur at the higher
conductivity.ItisbettersuitedtoflowthroughinstallationsinFS40andFF40adaptersandfittings,
butitcanalsobeusedindiptubes-FD40.