Conductivity Analyzers

Yokogawa is a recognized world leader for reliable conductivity equipment, providing credible and repeatable measurement solutions for maintaining and controlling even the most demanding process applications.

Yokogawa offers conductivity analyzers suitable for measuring the two most common conductivity measurement methods: contacting and inductive (also known as toroidal or electrodeless). Our conductivity analyzers provide high precision measurement and are built to withstand the harshest applications, requiring minimum maintenance and helping you achieve increased efficiency and reduced operating costs.



  FLXA202/21 FLXA402

Area Classification General Purpose, Class I Div II, Class I Div I General Purpose, FM Class I Div II pending
Power Supply 2-Wire Loop Powered 24VDC 4-Wire 100-240 VAC; 4-Wire 12-24 VDC
Communication 4-20mA, HART, FF and PA* 4-20mA, HART, Ethernet (Modbus TCP), RS-485 (Modbus RTU)
Contacts and Relays N/A 4 SPDT relay contacts with display indicators
Measurement Type Contacting Conductivity, Resistivity
Inductive Conductivity, Percent Concentration
pH, ORP (oxidation- reduction potential) , Contacting Conductivity, Resistivity
Inductive Conductivity, Percent Concentration, Dissolved Oxygen and 4-20 mA input

*FF and PF available in the Plastic FLXA21 for contacting conductivity and resistivity

The FLEXA™ series analyzers are modular-designed analyzers used for continuous online measurements in industrial installations. They offer single or multi-sensor measurement.


The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.

The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.

Compact, lightweight, and dripproof, the SC72 is the ideal Conductivity meter for field use. Features wide-range auto-ranging, automatic temperature compensation, self-diagnostic functions, and a large, easy-to-read LCD display.

Water Purification

Brine Manufacturing
Brine is often used within industrial processes such as food and beverage, refineries, textile dyeing house, and chemical plants as well as in municipalities or for commercial use as a final product applied to pavement roadways or commercial parking lots as an anti-icing or de-icing agent.

Conductivity measurement can be used as a reliable indicator of the real-time brine concentration. Utilizing online process analyzers removes the need for timely grab sample analysis. Yokogawa’s inductive conductivity analyzers help you achieve increased efficiency and reduced operating costs while realizing reliable brine concentration measurements.

Boiler Blowdown
The frequency and duration required for boiler blowdown is significantly affected by water quality. Raw water used to feed the boilers contains varying levels of impurities that must be removed to protect the boiler and associated equipment. Pretreatment processes such as reverse osmosis, ion exchange, filtration, softening and demineralization may be used to reduce the level of impurities. Unfortunately, even the best pretreatment processes will not remove all impurities and will continuously carry some dissolved mineral impurities into the boiler.

Improving feedwater quality through make-up water, chemical treatment, and proper blowdown control can significantly reduce costs including:

  • Reduced operating costs
  • Reduced maintenance and repair costs
  • Cleaner and more efficient steam
  • Energy savings
  • Increase efficiency and reduce operating costs using Yokogawa’s conductivity products.


Pharmaceutical Waters
Yokogawa’s conductivity transmitters and converters possess USP (United States Pharmacopoeia) functions to simplify and automate USP requirements. The FLEXA two-wire conductivity transmitter has the USP23/24 Stage One table pre-programmed in its software. When enabled, the transmitter will send a FAIL signal when the water exceeds the USP limit and can display and transmit the uncompensated conductivity that USP mandates for compliance recording.

The SC450 and DC402 four-wire conductivity converters have additional USP features with the ability to display and transmit the uncompensated conductivity for USP compliance, as well as the NaCl temperature compensated measurement, valuable for process control.

The USP23/24 Stage One table is pre-programmed into these instruments, and a FAIL alarm will be given if the conductivity limits are exceeded. Alarms on these units can be dedicated as USP “warning” alarms with user-defined safety margins. These “warning” alarms will inform the operator that his/ or her water is trending towards the USP limit and will allow him/or her to take preemptive corrective action.


Ion Exchange is a method for the exchange of ions between two electrolytes or between an electrolyte solution and a complex molecule. In most cases, the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic ion exchangers.

The dual channel process liquid analyzer gives you the ability to measure the bed’s inlets and outlets and calculate the ratio or % passage of the bed.


Heat Exchanger Leakage
Corrosion on the process side causes the heat exchanger tubing to mechanically fail, allowing the process fluid to leak into the condensate return line. This can cause serious damage to the boiler. Therefore, it is necessary to monitor the condensate downstream of the heat exchanger and to dump it as soon as it shows signs of contamination.

An excellent indication of contamination can be obtained by measuring the conductivity of the condensate because pure condensate has a very low conductivity value (1 to 10 µS) while contaminates (typically salts, acids or alkalis) that are introduced when leakage occurs have a significantly higher conductivity value. Because of the sizeable differences in values, even the slightest leak will sharply increase the conductivity reading. Any marked increase in the conductivity of the condensate indicates that leakage is present and that the condensate should be sent to drain.

Measurement and control of heat exchanger leakage can help prevent costly maintenance, repair, and downtime. The simple, essentially maintenance-free measurement of condensate conductivity gives operators the necessary information (or provides automatic control) to prevent severe damage to the boiler should a breakthrough of the heat exchanger occur.


Measuring the Electric Conductivity with Clean-in-Place (CIP) System

In the Pharmaceutical, Chemical and Food & Beverage industries, after manufacturing products, the cleaning and sterilization of tanks and piping are done with various cleaning solutions, fresh or hot water and steam. Clean-in-Place (CIP) is a system designed for automatic cleaning and disinfecting.

Yokogawa’s inductive conductivity liquid process analyzer takes measurements with good boundary surface precision over a wide range, earning it a reputation in the recovery of cleaning, which contributes significantly to reduce chemical and wastewater processing costs.

Percent Concentration

There are numerous industrial applications where measurements and/or control of a specific chemical strength of the process is critical for optimizing the production of the end product. These specific concentrations are obtained by mixing a full strength solution with water to achieve the desired percent concentration. Conductivity measurement is a reliable indicator of the concentration of most acid or base solutions.


Ion Exchange is a method for the exchange of ions between two electrolytes or between an electrolyte solution and a complex molecule. In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic ion exchangers.


In a semiconductor plant, a variety of chemicals are used in various manufacturing processes. The chemicals used for specific purposes are produced by diluting raw liquid with demineralized water using in diluting equipment, and the control of the concentration at this point is performed by conductivity measurement. 


Heat exchangers are devices that provide the flow of thermal energy between two or more fluids at different temperatures. Heat exchangers are used in a wide variety of applications. These include power production; process, chemical and food industries; electronics; environmental engineering; waste heat recovery; manufacturing industry; and air-conditioning, refrigeration, and space applications.


To defray energy costs, many industrial plants have their own boilers to generate steam to produce a portion of their energy needs. In addition to generating power, the steam may also be used directly in plant processes or indirectly via heat exchangers or steam jacketed vessels. 


Reverse osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.


There are many points in the processing of edible fats and oils that benefit from the use of analytical measurements. Inductive conductivity, contacting conductivity, gas density, and pH can be utilized to increase the quality of the end product, as well as protecting expensive processes.


The kraft process, also known as kraft pulping or the sulfate process, is a technology for conversion of wood into wood pulp that consists of almost pure cellulose fibers. Today, the kraft process is used in approximately 80% of paper production.


Yokogawa’s conductivity transmitters and converters possess USP functions that make this seemingly complex and troublesome requirement pain-free and automatic.

The input module you need depends on the Model Number of your FLXA Analyzer.

The input module you need depends on the Model Number of your FLXA Analyzer.

There is no way to "turn off" an unused input on a DC402. If you leave the terminals open you will get error messages.  Connect a simulated sensor to the unused input to clear the errors. Use a resistor on 11-12 to simulate the t...
With an Ohm meter check the following wires on the ISC40G sensor cable: 11 to 12 (Pt1000 or Thermistor) 13 to 17 – Sensor coil – expect low resistance. If unstable or above 100Ω it is bad. 15 to 16 - Sensor coil – ex...
Use the link at the top of the page to download a compressed (ZIP) file containing the GS Sheet and Manual for the SC150.
To test the conductivity input do the following:  Write down the cell constant and change it to 1.00 (this is not mandatory, it makes the math easier)  Place a jumper wire between 13 to 14 and another one on 15 to 16 (not necessary on t...
If you have lost the password for your SC150 you can use password   #PW123#   to get into the menu. The next thing you should do is to reset the password.
If you forget the password you have set in one of these transmitters there are only 9 passwords that can be set.  The password setting on the unit is a little difficult to understand. When you put a 3 digit code in service code 52 you are setti...
If you forgot the password to your FLXA Transmitter you can use the password #PW123# - this will allow you go into the menus. Remember to change or remove the password.
All Yokogawa analyzers use an open architecture with adjustable temperature compensation, adjustable isopotential point, and adjustable slope. They are compatible with all direct pH, ORP, and conductivity sensors. There are two exceptions to th...

Get the most from what exists currently and take advantage of new methods. Appeared in the March 2021 issue of InTech Focus, an publication.

Product Overviews




    In this 40 min session you will learn the fundamental requirements for aqueous conductivity measurements; the differences between "Contacting" and "Inductive" measurement techniques and which one to use for a particular application. As well as learn the importance of online diagnostics. The goal is to provide participants with simple techniques they can implement to improve their day to day operations and to identify causes of errors and how to correct them

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