Online Conductivity Analyzer

What is the Online Conductivity Analyzer?

An analyzer that measures electrical conductivity of a process liquid with contacting or toroidal sensors to indicate ionic content, concentration or purity. It is the right choice for boiler water, cooling systems, CIP control and ultrapure water monitoring.

Overview

An online conductivity analyzer applies an alternating voltage to a sensor and measures current to determine the ability of a liquid to carry charge. Two-electrode or four-electrode contacting sensors cover ranges from 0.055 microsiemens per centimeter, the conductivity of ultrapure water, to 20 millisiemens per centimeter. Toroidal inductive sensors, which use two coupled coils and have no electrodes in contact with the liquid, cover 10 microsiemens per centimeter up to several siemens per centimeter and resist fouling in acids, bases and slurries. The transmitter compensates for temperature at 25 C reference using a linear or non-linear algorithm, and can convert to TDS, salinity or concentration using stored curves. Cell constant accuracy, cable capacitance and polarization effects determine measurement quality, particularly at extremes of range.

How does it work?

Process analyzers replace manual sampling with automated measurement at or near the point of production. In-line sensors, such as pH or conductivity electrodes, sit in the pipe or tank. At-line and on-line systems draw a conditioned sample through a flow cell, filter and pressure regulator to a measuring module. Measurement techniques include potentiometry for pH, conductometry for ionic strength, optical luminescence or amperometry for dissolved oxygen, near-infrared spectroscopy with chemometric models for composition, and high-temperature oxidation with infrared detection for organic carbon. A transmitter digitizes the signal, applies temperature compensation and outputs 4 to 20 mA, Modbus, HART or Profibus to a PLC or DCS. Reliability depends on representative sampling, sensor cleaning, calibration and a validated relationship between analyzer and laboratory reference results.

What are the key features?

• Contacting sensors measure from 0.055 μS/cm for ultrapure water up to 20 mS/cm.
• Toroidal sensors have no electrodes exposed, so they resist fouling in aggressive streams.
• Non-linear temperature compensation suits ultrapure water, salts, acids and bases.
• Concentration curves convert conductivity to percent acid, caustic or TDS directly.
• Dual outputs and relay alarms support dosing control and high-limit alerts.
• Digital sensor heads store cell constant and calibration history.

What are the technical specifications?

A typical online conductivity analyzer configuration offers measuring range (contacting) of 0.055 μS/cm–20 mS/cm, measuring range (toroidal) of 10 μS/cm–2000 mS/cm, accuracy of ±1 % of reading, cell constant options of 0.01, 0.1, 1.0 cm⁻¹, temperature compensation of 0–130 °C, linear/NaCl/ultrapure and process pressure of Up to 10 bar. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Online Conductivity Analyzer is used in boiler and feedwater quality, clean-in-place phase separation, reverse osmosis permeate monitoring and acid and caustic concentration control. Across the wider Process Analyzers class, laboratories also deploy it for chemical reactor and neutralization control, boiler and cooling water monitoring and pharmaceutical and food fermentation control.

Which standards and certifications apply?

Relevant standards and methods include ISO 9001, IEC 61010-1, IEC 60079-0, ISO 10523, ISO 7888, ISO 8245, ASTM D1125 and ASTM E1655. Certification candidates for this model are CE, ATEX/IECEx for hazardous area versions and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Install sensors where the sample is representative and flow is continuous, avoiding dead legs, air pockets and stagnant zones. Provide isolation valves or retractable assemblies so sensors can be removed without stopping the process. Calibrate against certified buffers or standards at defined intervals and compare periodically with laboratory results. Cleaning frequency depends on fouling; automatic jet or ultrasonic cleaning reduces manual work. In hazardous areas, select equipment certified to the local explosion protection scheme. Keep spare sensors, reagents and filters on site. Document alarm limits, maintenance tasks and the action to be taken when the analyzer fails, because automatic control loops depend on its signal.

How do I select the right Online Conductivity Analyzer?

Choose contacting sensors for clean water and low conductivity, and toroidal sensors for corrosive or fouling liquids with higher conductivity. In an RFQ specify conductivity range, cell constant, process connection, temperature and pressure, fluid chemistry, calibration solutions and compliance such as USP <645> for pharmaceutical water.

How does it compare with other Process Analyzers variants?

Start with the variable that controls product quality or compliance and the response time needed. For ionic or acid-base control, pH and conductivity analyzers are the usual choice. For oxygen-sensitive processes, choose dissolved oxygen. For multi-component composition in real time, near-infrared with a calibrated model fits, while organic contamination in water is measured with TOC. Evaluate process conditions including temperature, pressure, fouling tendency, hazardous area classification and sample conditioning requirements. Compare accuracy, drift, calibration interval, maintenance effort, output protocols and alarm functions. Insertion or flow cell mounting, retractable housings and automatic cleaning matter in dirty streams. Plan a correlation study with laboratory methods before relying on analyzer values for control or release.