YOKOGAWA SC450G - Page 74

IM 12D08N05-01E
APP-8
<APPENDIXES>
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ttings,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application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applicationis10µS/cmto10mS/cm.Itisbettersuitedtoowthroughinstallations
inFS40andFF40adaptersandttings,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owthroughinstallations
inFS40andFF40adaptersandttings,butitcanalsobeusedindiptubes-FD40.
SC42-EP04 cc = 10 cm
-1
2-electrode sensor
This sensor is in the program for historical reasons. It makes little sense to select this
sensor for new applications.
It was used mostly for process water and light process solutions. The operating range can
be1to100mS/cmwithhigherreadingshavingaveryhighriskofpolarization.TheSC42-
EP18ortheSC42-EP08(4-elsensors)coverstheserangeswithmuchgreatercertaintyof
avoiding polarization.
SC42-EP08 cc = 10 cm
-1
4-electrode sensor
Process applications are where this sensor is used, including light fouling. The best range
ofapplicationis1mS/cmto500mS/cm.Thefour-electrodesystemcopeswithsome
contamination from the process, and eliminates the tendency for polarization to occur at the
higher conductivity. The upper limit is determined more often by chemical compatibility. The
epoxy material is attacked by many of the chemicals that are present in high conductivity
solutions. It is better suited to flow through installations in FS40 and FF40 adapters and
ttings,butitcanalsobeusedindiptubes-FD40.
SC42-TP08 (FP08) cc = 10 cm
-1
4-electrode sensor
Thesesensorsareforextremeapplications.ThePTFEorthePVDFusedforthebodyof
the sensor gives good chemical resistance for the strongly corrosive applications. These
sensorsareintendedforuseinranges10mSto1000mS/cm.Carefulselectionofthe
holderisneeded.ThePVDFsub-assemblyisanobviouschoicefortheSC42-FP08,and
thePPowttingoftenhassufcientcorrosionresistancefortheapplication.Inanycase
selection must be done with due regard to the process conditions.
The2-electrodeversions(SC42-T(F)P04doexist,butliketheepoxyversion(SC42-EP04)
they should be discounted for new applications.