Yokogawa FLXA402 Multi-Channel 4-Wire Liquid Analyzer
Overview of the Yokogawa FLXA402
The Yokogawa FLXA402 is a multi-channel 4-wire liquid analyzer converter that combines the functionality of the Yokogawa EXAxt series with modern digital sensor technology. It accepts traditional analog sensors as well as SENCOM 4.0 digital smart sensors, and with the appropriate modules it measures pH and ORP, resistivity and conductivity, inductive conductivity and dissolved oxygen. Up to five sensor measurements can be handled by one converter, and a colour touchscreen with menus in 11 languages keeps start-up and commissioning time short.
Seven Star LLC supplies the Yokogawa FLXA402 together with Yokogawa sensors, holders and cables to water utilities, desalination plants, power stations and process industries across the Sultanate of Oman and the GCC. As a trusted supplier with engineering support in Muscat, we help configure the sensor modules, outputs and mounting hardware for each analyzer point before quotation.
Operating Principle
The Yokogawa FLXA402 is a modular converter: the measurement function is defined by the sensor modules inserted into its two slots. Analog modules are available for pH/ORP with dual high-impedance inputs, for contacting conductivity and resistivity sensors, for inductive (toroidal) conductivity sensors, and for galvanic or polarographic membrane dissolved oxygen sensors. Digital modules connect the SA11 SENCOM Smart Adapter, which digitises pH, ORP and conductivity sensor signals at the sensor, or the DO71/DO72 optical dissolved oxygen sensors.
Each module processes its sensor signal with temperature compensation from Pt1000, Pt100, NTC and other elements, and the converter scales the results to its 4–20 mA outputs, relays and digital interfaces. When more than one sensor is connected, the Yokogawa FLXA402 can calculate derived values such as the ratio or percentage deviation between two sensors, which is useful for redundant pH measurement or for reverse osmosis rejection calculations. Sensor wellness indication and a software event log support predictive maintenance.
Engineering Design of the Yokogawa FLXA402
The converter is housed in a cast aluminium alloy case with a chemically resistant or high anti-corrosion coating and a flexible polycarbonate window, rated IP66 and NEMA Type 4X. The housing measures 165 × 165 × 168.5 mm, weighs at most 3.0 kg and has eight M20 cable entries, with G½, ½ NPT and M20 conduit adapters available. Optional universal, pipe, wall and panel mounting kits and a stainless steel hood make it suitable for outdoor field installation as well as analyzer panels.
The QVGA colour touchscreen displays values, trends and diagnostics, and the FLXA402-A version runs on 100–240 V AC while the FLXA402-D version uses 12–24 V DC. Output modules offer two isolated 4–20 mA outputs with one contact input, or four outputs with two contact inputs and one 4–20 mA input. Four SPDT relays handle alarms, wash cycles, hold indication and a fail-safe contact. Maintenance data can be exchanged by SD card, Ethernet, RS-485 or Bluetooth with Yokogawa FieldMate.
Key Features
The Yokogawa FLXA402 brings together the following features from its general specifications:
- Multi-parameter measurement of pH/ORP, conductivity/resistivity, inductive conductivity and dissolved oxygen in one converter.
- Connection of analog sensors, SENCOM 4.0 smart sensors via the SA11 adapter, and DO71/DO72 optical DO sensors.
- Up to five sensor measurements using a SENCOM SA module with the BA11 active junction box.
- pH accuracy of ±0.01 pH and conductivity accuracy of ±0.5 % of full scale with simulated inputs.
- Two or four isolated 4–20 mA outputs, accuracy ±0.02 mA, with HART 7 on the first output and NAMUR NE43 burn-out.
- Four SPDT relay contacts rated up to 250 V AC / 5 A, with high/low alarms, wash control and fail-safe function.
- Optional Modbus TCP over Ethernet or Modbus RTU over RS-485, plus Bluetooth for local access.
- IP66/NEMA 4X coated aluminium housing for field mounting at −20 to +55 °C ambient temperature.
Industrial Applications
The multi-sensor design suits water and wastewater treatment, where several parameters are measured at one point. In Oman, the Yokogawa FLXA402 is well suited to seawater reverse osmosis desalination plants at Barka, Sohar, Sur and Salalah, monitoring pH, ORP and conductivity of feed and permeate and dissolved oxygen in post-treatment. Power and water plants use it for boiler feedwater, condensate and cooling water chemistry, while municipal sewage treatment plants use dissolved oxygen and pH measurement to control aeration and dosing.
Refineries, petrochemical and fertiliser plants in Sohar and Duqm apply the Yokogawa FLXA402 to effluent neutralisation, produced-water treatment and chemical concentration measurement with inductive conductivity sensors. Seven Star LLC supplies the converter from Muscat with the right sensors and fittings, and can combine it with the Yokogawa FLXA21 dissolved oxygen analyzer for two-wire points, the Yokogawa ADMAG AXG magnetic flowmeter or the KROHNE OPTIFLUX 2000 electromagnetic flowmeter for flow measurement on the same water lines.
Technical Specifications of the Yokogawa FLXA402
The table summarises data for the Yokogawa FLXA402 from Yokogawa General Specifications GS 12A01F01-01EN (10th edition).
| Parameter | Specification |
|---|---|
| Model | Yokogawa FLXA402 4-Wire Converter |
| Measurement objects | pH/ORP, conductivity/resistivity, inductive conductivity, dissolved oxygen |
| Sensor inputs | 2 module slots; up to 5 measurements with SENCOM SA and BA11 |
| pH input range | −2 to 16 pH; ORP −1500 to 1500 mV |
| pH accuracy | ±0.01 pH (simulated input) |
| Conductivity range | Up to 2000 mS/cm output span; accuracy ±0.5 % F.S. |
| Dissolved oxygen | 0 to 50 mg/l (membrane sensors); optical DO71/DO72 sensors |
| Analog outputs | 2 or 4 isolated 4–20 mA, HART 7 on mA1, max. load 600 Ω |
| Contact outputs | 4 SPDT relays, max. 250 V AC 5 A / 50 V DC 5 A |
| Digital communication | Modbus TCP (Ethernet) or Modbus RTU (RS-485); Bluetooth option |
| Display | QVGA colour touchscreen LCD, 11 languages |
| Power supply | 100–240 V AC (35 VA) or 12–24 V DC (15 W) |
| Housing / protection | Coated aluminium alloy; IP66, NEMA Type 4X |
| Dimensions / weight | 165 × 165 × 168.5 mm; max. 3.0 kg |
| Ambient temperature | −20 to +55 °C |
| Hazardous area | FM nonincendive Class I, Division 2 version available |
How to Order
Send Seven Star LLC an RFQ for the Yokogawa FLXA402 with the parameters to be measured, sensor types and quantities, process temperature and pressure, required outputs and communication protocol, power supply and mounting method. Our instrumentation division in Muscat will confirm the model and suffix codes, recommend matching sensors and holders, and confirm current availability and lead time. The general specifications can be downloaded from this page, and our engineers support customers in Oman and the GCC through installation and calibration.
- Datasheet Yokogawa FLXA402 4-Wire Converter General Specifications (GS 12A01F01-01EN, 10th Ed.) Download
Yokogawa product families on this page
Pressure is covered by the DPharp transmitters: the EJX110A differential pressure transmitter, the EJX530A and EJA530E in-line gauge pressure transmitters and the EJX910A multivariable transmitter. The ADMAG AXW is the magnetic flowmeter line, and the YTA610 and YTA710 are temperature transmitters. Analyzers include the FLXA402 four-wire and FLXA21 two-wire liquid analyzers, the TDLS8000 tunable diode laser gas analyzer and spare parts for zirconia oxygen analyzers, such as the E7042UD cell assembly kit for the ZR22 detector. Control hardware includes CENTUM VP I/O modules like the ADV161 digital input module and the YS1700 programmable indicating controller.Where Yokogawa instruments are used
EJA and EJX transmitters measure pressure, level and DP flow throughout oil and gas, chemical and power plants. Zirconia oxygen analyzers and the TDLS8000 are used for combustion control on boilers and fired heaters. FLXA analyzers monitor pH, conductivity and dissolved oxygen in water and process streams, and CENTUM modules are bought as replacements for running control systems.Ordering Yokogawa parts: what we need
Send the model and suffix code and the serial number from the nameplate, and for CENTUM modules the style code as well. For transmitters without a code we need span, output protocol, wetted materials, process connection, housing and the approval required. For oxygen analyzer spare parts give the detector and converter models, for example ZR22G and ZR402G, and the part number.Browse Yokogawa products by category: PLC & I/O Cards, Flowmeters, Pressure Instrumentation, Automation Accessories, Temperature Instrumentation.
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