- Range
- Set by the electrode cell constant: about 0 to 20 microsiemens per centimetre at a constant of 0.01, up to 0 to 600 millisiemens per centimetre on the high specification controller
- Accuracy
- Stated as 2.0 class on the flagship and high specification controllers and as 1.5 percent of full scale on the compact controller
- Temperature
- minus 10.0 to 130.0 degrees Celsius, with automatic or manual compensation
- Temperature elements
- NTC10K, Pt1000, NTC30K or Pt100 depending on the controller, matched to the element fitted in the electrode
- Current outputs
- Isolated, one or two outputs, settable across the measurement range with a maximum load stated as 750 ohms
- Relays
- Two relays on the flagship controller and three on the high specification controller, the third available for a cleaning cycle
- Communication
- RS485 on the Modbus RTU protocol, with optional wireless transmission through an external module
- Display
- 2.8 inch monochrome liquid crystal on the flagship controller and a 4.3 inch colour screen on the high specification controllers, the latter switchable between numeric and trend display
- Protection
- Stated as IP54 on the flagship controller and IP66 on the high specification controller
- Electrodes
- Contact electrodes in stainless steel, polysulfone, PBT and graphite, a wide-range digital electrode, and an inductive electrode for fouling and concentrated duties
Conductivity is the one water parameter that can be measured without knowing what is in the water. It does not name an ion or report a concentration, yet it moves the moment anything dissolves, which makes it the standard way of watching a treatment process that is supposed to be removing things. A demineraliser that is working reads low; the same bed a day before exhaustion reads higher; and a condenser leak announces itself as a step in a number that was flat.
An online conductivity analyzer is therefore a process instrument rather than a laboratory one, and its usefulness rests on the electrode staying clean enough for the number to mean something.
Product overview
The range covers four controllers and two general-purpose instruments, together with a family of electrodes spanning ultrapure water to concentrated brine. The controllers differ in display, in the number of isolated current outputs and relays, in protection rating and in the languages they offer, but they share one principle: the measurement range is not set by the electronics at all.
What sets it is the electrode. A cell constant is the geometry term that converts a conductance into a conductivity, and it is chosen by the band of water the plant expects to see. This is why the same controller can be sold into a pure-water loop and into a brine line, and why choosing the controller before the electrode tends to produce a system that is insensitive where it matters most.
How the measurement is made
A contact electrode applies an alternating voltage across two surfaces of fixed area and separation in contact with the water, so that the current it carries is a measure of how freely the dissolved ions move. The alternating drive exists so that the measurement does not polarise the surfaces, and the fixed geometry is what allows the reading to be stated as a conductivity rather than as an arbitrary current.
That arrangement has limits at both ends. In very clean water the current is extremely small, so the cell needs a small constant and the cabling starts to matter. In dirty or concentrated water the surfaces foul and polarise, and the reading drifts for reasons that have nothing to do with the water. The inductive cell answers the second case by encapsulating two coils and letting the water itself provide the coupling, which removes all wetted metal from the measurement and removes the fouling problem with it.
In both cases the result is corrected to a reference temperature before it is displayed, because conductivity rises as the water warms and an uncorrected number cannot be compared with anything.
How to select the right analyzer
Start with the water rather than with the instrument. The band of conductivity expected in normal operation selects the electrode and hence the cell constant, and whether the water fouls a wetted surface decides whether a contact electrode is viable at all. Everything the controller offers is secondary to those two facts, because no amount of signal processing can recover a measurement the electrode cannot make.
Then confirm that the temperature element in the electrode matches what the controller expects, since a mismatch leaves the compensation unavailable and the reading incomparable. Only after that is it worth settling the electrical detail: how many outputs the receiving system needs, what the relays have to drive, whether a record is required, and whether the reading has to leave the panel.
Measurement limitations and selection considerations
The reading is a bulk property of the water, so it cannot distinguish between two dissolved species and it says nothing about the water being biologically or chemically fit for use. It is also the parameter most easily compromised by installation: an electrode mounted where a dead volume forms, where an air pocket can collect, or where the pipe does not run full will report something, and that something will be wrong in a way that looks like plant behaviour rather than instrument error.
The material describes these failure modes and the arrangements that avoid them, which is unusual and is carried forward because it is the most practically useful part of it. Two figures that a buyer would normally ask for are absent: the compensation coefficient the controllers apply, and the working life of the electrodes. Until the coefficient is known, a limit written against a compensated reading carries an unquantified uncertainty, and the page states that rather than implying a precision the material does not support.
Every value below is taken from source documentation. Where a parameter is not stated in the available material it is marked as information required rather than estimated.
