Multi Channel 4-Wire Analyzer FLXA402

The FLXA402 offers multiple connection possibilities, eliminating the need for multiple analyzers and providing greater flexibility. This four-wire analyzer includes a color HMI and an easy touchscreen operation with a simple menu structure in 9 languages for simple and efficient setup and configuration.

With its modular design, the FLXA402 analyzer offers a range of measurement choices with the respective sensor module, including pH/ORP, resistivity/conductivity (SC), inductive conductivity (ISC), percent concentration, dissolved oxygen (DO), and 4-20mA input. Dual sensor measurements offer additional functionalities, such as a calculated data function that can be customized.

FLXA402 Features

Support of Up to Five Sensors

The FLXA402 can connect up to five sensors, realizing interruption-free measurement even during maintenance. Multiple sensor measurement offers additional functionalities including a variety of calculated data as well as the option to program the analyzer as a redundant system.

Advanced Functions

With the FLXA402, one analyzer can accept: pH/ORP, Contacting Conductivity (SC), Inductive Conductivity (ISC), Dissolved Oxygen (DO), and Optical Dissolved Oxygen Sensors with self-diagnostic capabilities. Additional functions include:

  • Continuous measurement of sensor impedance, asymmetric potential, and slope, and continuous monitoring for electrode contamination/damage, burnout, and a decline in measurement liquid level (ex. pH Analyzer)
  • Online Sensor Wellness checking for predictive maintenance

DisplayExpert Guide: Clear Touch Panel Display for Improved Operability

The FLEXA series analyzer provides improved operability with intuitive touchscreen operation, featuring a clear display and user-friendly indication with 9 languages. The display of sensor status and estimated maintenance time improve efficiency. The interactive screen is housed in a robust aluminum die-cast housing.

Advanced Flexibility: Modular Design for Increased Scalability

The FLEXA™ series analyzer features a modular design with replaceable sensor modules, enabling the construction of a variety of systems. FLXA402 allows for the connection of up to five possible sensors resulting in a reduction in CAPEX and OPEX.

SENCOM SeriesPreparing for the Future

Industrial automation is moving toward SMART products, with sensors changing from analog to digital SMART. This transition can affect plant operations and take time to fully implement.

In addition to being a high performance standalone analyzer, the FLXA402 is also a component of the new Yokogawa SENCOM 4.0 Platform, a SMART sensor system that simplifies in field maintenance and calibration. With the SENCOM 4.0 Platform, upgrading to the next generation SMART product is easy, and an upgrade transfer can be done at any time with little impact on operations.

Data Mobility

SD card or Ethernet for easy data transfer and remote service, allowing for more in-depth process analysis. 


The treatment of wastewater from pulp and paper plants is a serious environmental concern. Yokogawa's submersion holder with an ultrasonic+air-jet cleaner (customized product) can reduce the manual cleaning frequency to just once every one or two months.

Industry:Pulp & Paper


Wastewater from electroplating facilities and certain types of chemical plants contains toxic forms of hexavalent chromium such as chromate and dichromate. The hexavalent chromium in this wastewater must be reduced before the water can be discharged. This requires a two-step process: hexavalent chromium (CR6) is reduced to trivalent chromium (CR3); and CR3 is precipitated as chromium hydroxide.

Industry:Electrical and Electronics


Continuous technology improvement is ongoing in the pulp & paper industry to obtain the best possible performance. The improved plant performance translates to the higher quality improvement and lower cost, and simultaneously environmental friendly plant operation.


Power plant boiler houses designed to burn coal or high sulfur oil are required by Federal and State pollution regulations to "scrub" (remove) sulfur dioxide from flue gasses to meet emission limits. SO2 in flue gasses is known to be harmful to the environment, as it is one contributor to the formation of acid rain. pH control is critical for the proper functioning of the scrubber system.


In the past, the boiler feed tank systems in sugar factories had to be checked several times a day to make sure there were no sugar solution leaks. This was a very laborious process and, as continuous monitoring was not possible, monitoring results were not reliable. When a leak occurred, recovery operations were very costly and time-consuming. (AN10D01K01-02E)


In flue gas desulfurization systems that use magnesium hydroxide (Mg(OH)2) slurry, the consumption of the desulfurization agent (Mg(OH)2) is controlled by using online pH analyzers. A great concern in the pH measurement is heavy staining of the pH electrodes by the Mg(OH)2 slurry. To ensure accurate measurement, frequent cleaning of the electrodes with an acid is required, adding to both maintenance workload and cost.

Industry:Chemical, Power

Default pre-programmed, see Appendix in Instruction Manual Configurable by expert HOST (= Yokogawa device FLXA402, Fieldmate, NOT UM33A-S)  Remark: some error configuration depends on the type of sensor that is connected. This will be autom...
No, FieldMate and FLXA402 are the only communication devices available to work with the SENCOM 4.0.
Yes, that is possible. It is the same as the standard analogue sensors directly connected to the FLXA402. 
Yes. It does not matter if an order for the conduit adapter (option) is entered or not, standard plastic cable glands and blank plugs will be supplied.
Yes, when ordering the FLXA402 with Ethernet port it can be connected to the DCS.
The BA11 is delivered with a mounting bracket which can be attached to the back of the FLXA402. Also, pipe and wall-mounting are available. It is advised to use the 1-meter WU11 cable when mounting it on the back of the analyzer. ...
Yes, it can be used as an analogue sensor connecting to the analogue module of the FLXA402.
When using only analog sensors the maximum number of sensors connected are two. Then the maximum needed outputs are four (suffix code A4). When using the SA11 Smart SENCOM adapter a maximum of 5 sensors can be connected. To be able to output all thes...
Calibration data will be stored in the ID chip implemented in the variopin connector of sensors upon calibration in the lab. Upon connection of the sensors to the SENCOM Smart Module in the field, the data form sensor will be uploaded in to the SA11 ...
No, there is a different Sensor Adapter for each parameter. However, when SENCOM is selected in the FLXA402, there is only ONE SENCOM module and it does not need to be changed. ...
This is not possible. The purpose of the SD card is: to save/load configuration parameter data into/from FLXA402 internal storage or export/import to/from SD card. to export the logbook. to update the firmware of FLXA402 converter. ...
It will be supplied when FLXA402 is ordered with analog pH or SENCOM module.
With the SA11 a maximum of five sensors can be connected to the analyzer. To one SENCOM module a total of four SA11+ analogue sensors can be connected using the BA11 active junction box. See below the possibilities.   Slot 3 ...
"1" is the slide switch for HART only, and "2" is only for use by Yokogawa Service personnel. (refer to IM 12A01F01-02EN) ...
Please refer to the spec table below.
No, the contacts are passive outputs. It cannot drive a pump directly.
See the display comparison image below.
See below for the detailed drawing.
Yes, the FLXA402 can directly power the Visiferm and DO70G. The modelcode selection for this is “D5”. It cannot be used as an analog sensor so MS code “D1” is not applicable for the Visiferm and the DO70G. D1 is available for ...
The WU11 cables are used between the BA11 and the FLXA402. WE10 is used between the FU20-VS / PH21-VS and FU24-VS and the SA11. ...
SPS24 PC software that was used with the first generation of SENCOM will not work with the SENCOM 4.0 platform and Smart SENCOM Adapter. The only software available for SENCOM 4.0 is FieldMate and the free Calibration Tool software.  The fr...
The SA11 has locally stored a logbook for 50 calibration data points and 50 events. So total 100 logging events. This function cannot be read by addressing the Modbus content. This function is reserved for Yokogawa expert host. This can be FLXA402/FL...
Yes, when selecting -D5(digital sensor(DO70G), FLXA402 can power an optical DO sensor.
Without using the BA11 active junction box the maximum distance is 100 meters. When using the BA11 it is possible to extend a further 100 meters. Making it a total of 200M. ...
SA stands for SENCOM Adapter (Model SA11); it is a product platform succeeding the first SENCOM generation of products from Yokogawa. The SENCOM Smart Adapter uses the digitalization embedded but in a detachable and reusable format. This product is p...
No, calibration can be done on the FLXA402 screen, or by bring a tablet with FieldMate into the field using the Bluetooth connectivity with FLXA402, or with Fieldmate using the BT connection with IB100.
When using analog DO sensor, e.g. DO30G, -D1 needs to be selected. When using optical DO sensor, e.g. DO70G, -D5 needs to be selected.
No, this is not possible both platforms have different Modbus registries.

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