Liquid Analyzers

What is a Liquid Analyzer?

Liquid pH ORP analyzers and conductivity analysers are used for monitoring process chemistry including water quality, providing process optimization and control. Common measurements include pH, ORP, conductivity, resistivity, percent concentration, and dissolved oxygen.

Industrial Applications of Liquid Analyzers

  • Industrial conductivity sensor
  • Chlor/Alkali Plant pH/ORP Measurements 
  • Brine Manufacturing
  • Headbox pH Monitoring
  • Sugar Refinery pH Control
  • Dairy Waste Water Processing
  • More

What is conductivity in water treatment?

In water treatment, water must pass a conductivity test to see if it passes an electrical current. Conductivity in water is related to inorganic solids, including ions carrying a negative charge (chloride, nitrate, sulfate, phosphate anions) and ions carrying a positive charge (sodium, magnesium, calcium, iron, aluminum cations). The conductivity level of water is also dependent on temperature.

Benefits of Liquid Analyzers

Liquid analysis is essential for protecting capital assets including boilers and cooling towers, by preventing corrosion, minimizing maintenance, and maximizing uptime.

Yokogawa is a recognized world leader for reliable liquid analytical equipment, providing accurate and repeatable solutions for maintaining and controlling even the most demanding process optimization and control applications with unparalleled ease of operation.

Book a On-Site Demo >

Liquid Analyzers
Use our Liquid Analyzer Sensor Wiring Guide to easily find the correct wiring for your liquid analyzer sensor.
  • SENCOM™ SMART Digital Sensors

    • SENCOM™ SMART Digital Sensors
    • Maintain specific measurement/calibration data on integrated chip
    • Data exchanged between sensor and process transmitter or PC using data management software like SPS24
    See More
  • pH and ORP Analyzers

    pH and ORP meters, analyzers and transmitters are used for continuous process monitoring of pH and ORP to ensure water/product quality, monitor effluent discharge, batch neutralization, pulp stock, scrubbers, cooling towers, chemical, water/wastewater treatment and many other applications.

    See More
  • pH and ORP Sensors

    • pH and ORP sensors
    • Proper pH electrode/sensor selection critical for optimal measurement results
    • Installation options include retractable, flow thru, immersion, and direct insertion
    See More
  • Conductivity Analyzers

    • Conductivity analyzers, meters, transmitters
    • Continuous process measurement and monitoring
    • Conductivity, resistivity, WIFI, demineralizer water, RO water, percent concentration, boiler blowdown, TDS
    See More
  • Conductivity Sensors

    • Conductivity sensors and electrodes
    • Process conductivity, resistivity, WIFI, demineralizer water, RO water, percent concentration, boiler blowdown, and TDS 
    • Retractable, flow thru, immersion, and direct insertion
    See More
  • Dissolved Oxygen Analyzers

    • Dissolved Oxygen (DO) meters, analyzers and transmitters
    • Continuous process measurement and monitoring
    • Milligrams per liter (mg/l),parts per million (ppm), parts per billion (ppb), or % saturation. 
    See More
  • Dissolved Oxygen Sensors

    • Dissolved Oxygen (DO) sensors/electrodes
    • Polarographic, galvanic, optical measurement
    • Floating ball, retractable, flow thru, immersion, direct insertion installation
    See More
  • Turbidity Analyzers

    • TB820D next-generation digital Turbidity meter
    • Turbidity analyzer connects to FLXA402T.
    • LED light source, flat window structure cell, new diagnostic functions, ultrasonic cleaning
    See More
  • Chlorine Analyzers

    • Non-reagent type chlorine analyzer for measuring free chlorine 
    • Reagent type chlorine sensor for measuring free chlorine or residual chlorine (total chlorine) 
    See More
  • Product Finder

    This web tool makes it easier to find products according to the application, measurement conditions and required specifications.

    See More



Water Supply Treatment
FAST/TOOLS, STARDOM, Flowmeters, Liquid Analyzers

  • Bali's water treatment plant decided to employ the latest reliable control system in order to increase availability and quality of operation.
  • Centralized control system using FAST/TOOLS provides the sophisticated and flexible operation.

SMART digital sensors and advanced data management software enhance reliability and process safety.

Application Note

Conductivity measurement can be used as a reliable indicator of the real-time brine concentration. Using an online process analyzer removes the need for timely grab sample analysis. 


Dairy wastewater is a mixture of organic compounds, suspended solids, fats, and bacteria that can produce a film or coating on equipment in the process. 


Problems at the wet end of a paper machine can rarely be corrected downstream. That is why monitoring and controlling pH in pulp stock is critical to the paper-making process. Essentially, at every stage in the manufacture of paper, correct pH values play a vital role. Variations in the pH value at the headbox have a negative effect on the quality of the paper produced. Proper monitoring ensures minimizing plugging and fouling problems that occur with pH measurements in paper mills. 


After extraction from sugar cane or sugar beets, the juice must be purified to remove the many other organics and minerals that accompany it. The processing to accomplish this is heavily dependent on reliable pH measurement and control as illustrated. 


Yokogawa’s Process Liquid Analyzers series help pigment producers achieve a more reliable and accurate analysis of pH during industrial bioprocesses, improving product quality with less total operation costs.


Read this eBook to learn how to best leverage the latest measurement instrumentation to avoid incidents and improve productivity. You will also find valuable information about overcoming common CIP challenges and stories of success.

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.

To prepare the sensor for installation follow the below steps: Carefully remove the watering cap. Rinse the sensor with water. Check the interior of the pH glass membrane for air bubbles. Allow any bubbles to rise to the top by shaking the sensor ge...
Yes. It does not matter if an order for the conduit adapter (option) is entered or not, standard plastic cable glands and blank plugs are supplied by Yokogawa.
Why am I getting a temperature compensation 1 error on the analyzer when I'm using either an inductive or contacting conductivity sensor? Common causes for temperature compensation errors.
Edition 1

Why am I getting a temperature compensation 1 error on the analyzer when I'm using either an inductive or contacting conductivity sensor? Common causes for temperature compensation errors.

Yes, in the logbook of both the SSA and ID-chip inside sensor. Remark: when sensor is re-connected to SA11, the sensor logbook information will overwrite the logbook information inside the SA11.
1. Manually by using a HOST (FLXA402, Fieldmate) 2. By calibration of temp. coefficient Remark: it is a process calibration which is NOT sensor specific. This means it will not be stored in the sensor ID-chip.
No, FieldMate and FLXA402 are the only communication devices available to work with the SENCOM 4.0.
The area classification of the SA11 at the time of release is General Purposes with IP 67 rating for ingress protection. Once the FLXA 2-wire solution is upgraded to work with the SA11, all necessary certifications for Class I Div I and Class I Div I...
SA stands for Sencom Adapter (Model SA11). This is one piece of a new product platform. The SENCOM 4.0 series has been released to replace the original SENCOM generation of products from Yokogawa. The new SENCOM 4.0 SA11 Smart Adapter uses ...
The current termination of sales date for the EXA450G series is estimated to be around April of 2020. As the date gets closer announcements will be made. Following Yokogawa's normal practice, all spare parts will still be available for five ...
The BA11 is delivered with a mounting bracket which can be attached to the back of a FLXA402 or FLXA202. It also can be used to mount the BA11 on a pipe or wall. ...
In most cases the SA11 Smart Adapter is mounted directly on the sensor. If the temperature is high the temperature limits of the SA11 Smart Adapter (-30 up to +125°C (-22 up to +257°F)) may require that the adapter be remotely mounted. Optio...
Slide switch #1 is to disable HART communications. Turn this switch OFF to ENABLE HART communications. Turn it ON to DISABLE HART communictions.  Slide switch #2 is not for customer use. DO NOT TURN IT ON. Leave it in the OFF position. Th...
For example, initially, we used it for pH measurement, later we would like to use it with a conductivity sensor. No due to the variopin pin out allocation, there is a different SA11 Smart Adapter for each parameter. If the FLXA402 has a SENCOM...
If the FLXA402 has only one Analog Input Module the display will look like the Single Input above.  If the FLXA402 has two Analog Input Modules the Display will look like the Dual Input above. You can select which input is active by clicking ...
The Modbus registers for the new Sencom 4.0 devices have changed, they are not the same is the older SENCOM devices. The SENCOM 4.0 Modbus Register information for the FLXA402 is available in TI12A01F01. You can download this document from...
Yes. This setting only changes the SA11 setup parameters. It does not change the information stored in the ID-chip inside the sensor.
Yes, that is possible. The calibration procedure is exactly the same as the standard analog sensors directly connected to the FLXA402.
From the GS sheet you will find: EMC Regulatory Compliance: North America:  EN 61326-1 (Class A, Table 2) EN 61326-2-3 Australia and New Zeeland: CISPR11 Korea: Electromagnetic ConformityStandard Class A Regulatory Compliance Mark Level...
Why is pH Calibration important? How to clean pH glass? Which pH buffers should I use?  How fresh should pH buffer solution be?  How long between calibrations?
Edition 1

Why is pH Calibration important? How to clean pH glass? Which pH buffers should I use?  How fresh should pH buffer solution be?  How long between calibrations?

Yes, it can be used as an analogue sensor connecting to the analog inputs of the pH transmitter. ...
No, the PH21 does not have a Liquid Earth (LE) electrode. The LE is not needed in many of the applications we target for this sensor. When necessary a seperate Liquid Earth connection can be connected to the SA11 using the screw termin...
The PR20, PR4A, and ISC40PR were discontinued in April of 2010. The PR10 is the replacement for these products. It is larger than the PR20 so installation changes are necessary in most cases. The PR20 had a 1" NPT process connection, and th...
PH150 Forgot Password?
The PH150 allows the use of passwords to limit access to the Calibration functions and access to the Configuration functions. If these functions have been protected with a password and the password is not available there is a way to bypass the prote...
Error 130 & 131 are display errors. The PH450 calibrates the display each time it powers up. Error 130 or 131 means this calibration failed. Cycle the power to the unit and allow it to calibrate the display again. If after 6 times the error is st...
An Error 2 means that the calculated asymmetry potential is outside the acceptable range. The Asymmetry Potential (AS), also referred to as the millivolt offset, is an indication of the condition of the reference electrode. Theoretically when the ele...
The Error 3 is related to the slope value on a pH loop, indicating that the slope value is outside of the allowable range. The Slope (SL), also referred to as the efficiency of the electrode, is an indication of the condition of the pH electrode. The...
Air bubbles are normal in pH sensors and in some reference sensors. They are necessary because the pH sensor is a sealed device with no vent. Without the air bubbles the expansion and contraction of the liquid with temperature changes could cause the...
Yes. The Cation Differential pH and ORP sensors have a glass electrode that needs a 2 point calibration performed regularly. Because of the Cation Reverence electrode you must use special buffers with a constant sodium ion concent...
A tiny crack in the membrane of a glass electrode is not always visible to the naked eye. Frequent shocks may create cracks in the glass that cause measurment errors. These cracks will cause the analyzer to read 0 mV and the ...
It is very important that the cables maintain a very high impedance. If any moisture penetrates the cable the impedance will drop and the cable will short out the voltage generated by the pH sensors. This will cause errors or a total loss of mea...
Often, Instrumentation technicians like to shorten cables to match the installation. This is strongly discouraged with Analytical Sensors. Yokogawa has designed cables with a special layer of conductive plastic to ensure maximum noise ...
The reference potential difference between 1 molar and 3.3 molar is approximately 30 mV. The sensitivity of a pH sensor at reference temperature is 59mV/pH. So if you combine a measuring cell filled with 3.3mol KCl with a reference cell with 1mol KCl...
Yokogawa's buffer solutions have a guaranteed shelf life of 12 months from the date of shipment. The exception to this is the sodium buffer solutions used to calibrate the differential pH sensors (part numbers K1520BF, K1520BG, K1520BH, K152...
We recommend using pH buffers only once. If you want to use the same buffers for more analyzers, then you must avoid contamination of the buffers by the sensors. The sensor must be cleaned and washed carefully before inserted into the buffer. A senso...
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...
That is possible but not guaranteed. The 225 mm sensor body is longer, so it has more electrolyte. Often the reference electrode fails because the electrolyte is depleted as it diffuses through the reference junction into the process. With ...
Most pH sensors with a glass membrane cannot be mounted upside down. To absorb the thermal expansion of the internal buffer solution there is always a sizeable air bubble inside the sensor. When the sensor is mounted upside down the reference element...
Yokogawa offers the PH18 sensor. This sensor is nonglass and suitable for regular CIP and SIP cycles. ...
In a dual input FLXA202 or FLXA21 analyzer you can use a HART Splitter to convert the HART® dynamic variables into current outputs or contact outputs. The model number is "1W-KFD2-HLC-EX1.D" and the description is "P+F HART Splitte...
Yokogawa's pH and conductivity sensors include a temperature sensor to allow for temperature compensation. The pH and conductivity sensors have a relatively large temperature mass and respond slowly to the changes in the process temperature. This...
Generally we state that the pH analyzer is as accurate as the care that is given to the device allows. With lots of care you can achieve 0.05 pH accuracy. With normal care you achieve 0.1 pH Without care the measuring error can be pH 0.5 or more...
The PH150 and SC150 were discontinued in 2004. The Manual and General Specification sheet are no longer available on Yokogawa's website. Use this link to download a zip file containing both documents.
The TM20 pH meter was discontinued over 20 years ago, but the manual is still available.  If you have trouble downloading it, send us an email at or call 800-524-7378.
First, check the grounding. A bad ground can cause this failure.  Next: cycle the power to the unit. Shut the power off for 30 seconds then restart.  If that doesn’t clear the error reset the analyzer to factory defaults. Be ...
Performing a two point calibration for an ORP sensor may make a user more confident in the measurement because it ties the measurement to two known millivolt values, offsets and slope values. When performing a pH calibration, the 2nd point&...
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...
Soak the sensor in 5 - 10% Hydrochloric acid (HCl) in water solution. for 5 - 10 minutes, then rinse. If you have trouble finding 5 - 10% HCL you can buy muriatic acid at a building supply house and it is usually 20 - 30% HCL. Check the label. Dilute...
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.
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...
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...
The difference is the temperature sensor. The SC41 has a Ni100 temperature element and the SC42 has a PT1000 temperature element. PT1000 is a better temperature element, but some old electronics will not accept a PT1000 temperature element, so the SC...
Use the link at the top of the page to download a compressed (ZIP) file containing the GS Sheet and Manual for the SC150.
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...
You can test the ISC converter by simulating a conductivity reading using an ISC40 sensor. You will need: A known working ISC40 sensor. A piece of wire One or two decade box/resistance sources. Connect sensor wires 13-17 to analyzer. ...
Click the link at the top of the page to download the DO400 Manual.
How to startup a new sensor, or how to replace the Membrane Cap and Electrolyte.   Startup of a new Oxygold G sensor: The Oxygold G sensor is shipped dry with a protective cap over the end of the Membrane Cartridge. CAUTION: The electrolyte ...
Most of our pH sensors have a noble metal solution ground and our transmitters measures two values: 1.  the voltage between this solution ground, or liquid earth sensor and the pH sensor, and 2. the voltage between this solut...
This is a well-known pH problem that we call Diffusion Potential. If the sensor junction is partially plugged the electrical contact between electrolyte and process is not good. This results in a high diffusion potential and an error i...
NO!  Sensors that are not used need to be stored in a solution that guarantees that the sensor is ready for use. When the sensor is stored in pure water the salt will be washed out of the junction of the reference cell. This causes the sensor t...
Yes and No.  Yes - after cleaning you need to verify that the analyzer is reading correctly. The easiest way is to see how it reads when placed in 2 pH buffer soltuions. This is what you do when calibrating.  No - If the readings are with...
First - when you receive a new Bellomatic sensor it is shipped with a rubber stopper inserted into the pressure port on the bottom of the sensor. You must remove this stopper before putting the sensor in service. DO NOT DISCARD THIS STOPPER! Put it i...
Yes, the SENCOM Module in these sensors allows a Modbus Master to connect using Modbus RTU protocol and access the following data: pH Temperature compensated pH ORP pH compensated ORP rH Temperature Junction resistance value Sensor details ...
Yes, the input module can be changed in the Converter.    See the FAQ: Which Input Module do I order for my FLXA21/202 analyzer? ...
The short answer to this question is NO. But, there is a long answer that will give you another option. Yokogawa has created a Submersible Sensor Kit (part number M1289XT) for the FU20 pH sensors - M1289XU for the FU24 sensor). It is also known as ...
PH Sensor Cleaning
Cleaning pH Sensors Basic Steps  Rinse electrode in clean water Clean by immersing the electrodes in a cleaning solution (see below).  Rinse Again Check with buffers Cleaning Solutions: If you know a specific way to clean the sens...
Sensor lifetime is difficult to predict as it is dependent on a number of different factors such as pH value, temperature, pressure, the composition of the process liquid, maintenance activity is taken, storage conditions, and sensor handling. ...

Sensor lifetime is difficult to predict as it is dependent on a number of different factors such as pH value, temperature, pressure, the composition of the process liquid, maintenance activity is taken, storage conditions, and sensor handling.

Yes you can, but we do not recommend this method. A pH sensor has a reference electrode that has a low impedance to the process. If the process suffers from common mode voltages or ground loops it will be difficult to measure the ...
The FF20 flow through holder for PH can be ordered using the "pH Selection Guide Matrix" so that an entire system can be ordered with one line item. This does not work if you want a FF20 with an FU20 sensor. The Matrix does not contain the ...
If you have set a password and have forgotten it you can use the password "MOON" to get into the configuration menu. Then you will be able to modify/view the password that is set in the unit.  Note: if you have not set a password just...
The password to get in all the maintenance and commissioning menus is 16 
ZR22S: Option "B" Adder
This is the Japanese GS sheet, containing a number of options we rarely sell here in the US. Contact Support at 800-524-7378 or for price and delivery information.    ...

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





SENCOM- The Next Generation in SMART Liquid Analyzers

Yokogawa’s SENCOM SMART Sensor Platform is an innovative analyzer platform that optimizes maintenance, reduces configuration time, and simplifies in-field maintenance and calibration. Yokogawa is a recognized world leader for reliable liquid analytical equipment, providing accurate and repeatable solutions for maintaining and controlling even the most demanding process applications.


Nick Crowe discusses whether to calibrate or validate your analyzers. He demystifies the differences between both options and uncovers the truth about performing either.


We invited Nick Crowe, our Product Manager for Analytical Products to debunk myths around Liquid Analysers. In part 1 of this series, Sean asked him whether the maintenance-free analyzer is a myth?


Looking for more information on our people, technology and solutions?

Contact Us