Brand: Yokogawa

Yokogawa FLXA21-D P-D-CH-D1-NN-A-N-LA-N-NN/U Dissolved Oxygen Analyzer

Name: Yokogawa FLXA21-D DO Analyzer – Datasheet & Price Quote
Brand: Yokogawa

Description

Overview

The Yokogawa FLXA21-D P-D-CH-D1-NN-A-N-LA-N-NN/U is a 2-wire module-type liquid analyzer transmitter from Yokogawa’s FLEXA series, factory-configured for dissolved oxygen (DO) sensor input. Built on the same proven FLXA21 platform used for pH/ORP, conductivity, and inductive conductivity measurement, this DO-configured variant accepts both galvanic and polarographic dissolved oxygen sensors, giving process engineers a single reliable transmitter platform for continuous on-line oxygen monitoring in water treatment, power generation, and pharmaceutical process water systems.

With fast quotation turnaround and technical support, Seven Star LLC proudly supplies the Yokogawa FLXA21-D dissolved oxygen analyzer to power plants, water treatment facilities, and process industries across the Sultanate of Oman, Muscat, and the wider GCC region. Our instrumentation division validates the exact model code against each customer’s sensor configuration before dispatch, ensuring the ordered analyzer arrives correctly configured and ready for commissioning on regional projects.

Operating Principle

The Yokogawa FLXA21-D operates by accepting a low-level current signal from an external dissolved oxygen sensor and converting it into a calibrated, temperature-compensated DO reading. For galvanic-type DO sensors, the sensor generates its own driving voltage internally; for polarographic-type sensors, the FLXA21-D itself supplies the external driving voltage required for the electrochemical reaction at the sensor tip. The transmitter accepts an input range of 0 to 50 µA for galvanic sensors and 0 to 1 µA for polarographic sensors, translating the raw current signal into a dissolved oxygen concentration across a 0 to 50 mg/l (ppm) measurement span.

Because dissolved oxygen readings are highly temperature-dependent, the FLXA21-D incorporates automatic temperature compensation using Pt1000 or NTC22k temperature elements built into the DO sensor assembly. The transmitter continuously monitors sensor health — tracking impedance, membrane condition, and signal stability — and raises diagnostic alerts when the sensor requires cleaning, recalibration, or replacement. This self-diagnosis capability reduces unplanned maintenance visits and keeps continuous water-quality monitoring loops running with minimal operator intervention.

Engineering Design of the Yokogawa FLXA21-D

The Yokogawa FLXA21-D is housed in a rugged, wall or pipe-mountable enclosure suited to both indoor plant rooms and outdoor field installations. A high-visibility backlit LCD display presents live DO concentration and process temperature simultaneously across dual measurement channels, while a sealed four-button keypad behind the front cover allows on-site calibration, range configuration, and diagnostic review without opening the enclosure to the elements. Cable entry is provided through multiple gland fittings on the underside of the housing, keeping wiring connections protected from moisture ingress in humid GCC coastal and desalination plant environments.

As a genuine 2-wire loop-powered device, the FLXA21-D transmits its 4-20 mA output signal over the same two conductors used to supply power, dramatically simplifying field wiring compared to separately powered 4-wire analyzer systems. The modular internal architecture allows the same physical transmitter housing to be factory-configured for pH/ORP, conductivity, inductive conductivity, or dissolved oxygen measurement simply by changing the internal sensor input module and firmware configuration — the P-D-CH-D1-NN-A-N-LA-N-NN/U code specifies the exact DO input configuration, output, and approval options for this unit.

Key Features

The Yokogawa FLXA21-D dissolved oxygen analyzer combines flexible sensor compatibility with rugged 2-wire field construction. Core capabilities include:

Compatible with both galvanic and polarographic dissolved oxygen sensors on a single transmitter platform.
Dissolved oxygen measurement range of 0 to 50 mg/l (ppm) with automatic Pt1000/NTC22k temperature compensation.
Continuous self-diagnostics that monitor sensor condition and flag cleaning, calibration, or replacement needs.
Genuine 2-wire, loop-powered 4-20 mA operation that simplifies field wiring and reduces installation cost.
Backlit dual-channel LCD display for simultaneous viewing of DO concentration and process temperature.
Rugged wall or pipe-mount enclosure suitable for indoor and outdoor installation in humid process environments.
Shared FLEXA hardware platform with pH/ORP and conductivity variants, simplifying spares strategy across a plant.
Factory-configured exact model code ensures the ordered unit matches the customer’s specified sensor and output requirements.

Industrial Applications

Dissolved oxygen monitoring with the Yokogawa FLXA21-D is essential across power generation, water treatment, and process industries throughout Oman and the GCC. In power plant boiler feedwater and condensate systems, the analyzer verifies that dissolved oxygen levels remain low enough to prevent corrosion of high-pressure steam piping and heat exchangers, protecting critical rotating and static equipment from oxygen-driven pitting.

With engineering support in Muscat, Seven Star LLC distributes the FLXA21-D to municipal and industrial water treatment plants, RO desalination facilities, and pharmaceutical process water systems within the Sohar and Salalah economic zones, where continuous DO monitoring supports both regulatory compliance and process optimization. Aquaculture and wastewater aeration basin operators across the region also depend on this analyzer to maintain optimal oxygen levels for biological treatment processes, with Seven Star LLC’s technical support helping to plan sensor or transmitter replacement.

Technical Specifications

Full technical parameters for the Yokogawa FLXA21-D dissolved oxygen analyzer:

Parameter	Specification
Model	Yokogawa FLXA21-D P-D-CH-D1-NN-A-N-LA-N-NN/U
Measurement Type	Dissolved Oxygen (DO), 2-wire configuration
Compatible Sensors	Galvanic-type and polarographic-type DO sensors
Input Range	0 to 50 µA (galvanic), 0 to 1 µA (polarographic)
Measurement Range	Dissolved Oxygen: 0 to 50 mg/l (ppm); Temperature: -20 to 150°C
Accuracy	±0.05 ppm or ±0.8% F.S., whichever is greater
Temperature Compensation	Pt1000 (DO30 sensor) or NTC22k (OXYFERM/OXYGOLD sensors)
Output	2-wire, loop-powered 4-20 mA
Display	Backlit dual-channel LCD with local keypad configuration
Enclosure	Wall or pipe-mount, weatherproof field housing
Model Code Configuration	P-D-CH-D1-NN-A-N-LA-N-NN/U (verified corrected code, DO input)

Request a Quote for Yokogawa FLXA21-D P-D-CH-D1-NN-A-N-LA-N-NN/U Dissolved Oxygen Analyzer

To submit a formal Request for Quote (RFQ), verify the exact model code configuration, or download the complete technical datasheet for the Yokogawa FLXA21-D dissolved oxygen analyzer, please contact the instrumentation division at Seven Star LLC today. Backed by manufacturer datasheet documentation, our engineers cross-check every RFQ model code against Yokogawa’s official configuration tables before confirming an order, ensuring the unit you receive is built exactly to your process requirements.

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About brand

Yokogawa instruments are ordered by model and suffix code, a string such as EJX110A followed by option characters that fix span, materials and approvals. Founded in 1915 and headquartered in Tokyo, Yokogawa makes field instruments, process analyzers and the CENTUM control system used in refineries, gas plants and power stations.

Seven Star LLC is an independent supplier listing Yokogawa pressure transmitters, flowmeters, temperature transmitters, analyzers and CENTUM I/O modules for users in Oman and the GCC.

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.

Frequently Asked Questions

What sensor types does the Yokogawa FLXA21-D support?

The FLXA21-D accepts both galvanic-type dissolved oxygen sensors, which generate their own driving voltage, and polarographic-type sensors, which require an external driving voltage supplied by the transmitter.

Does the FLXA21-D save on installation and wiring costs?

Yes. As a genuine 2-wire, loop-powered analyzer, the FLXA21-D transmits its 4-20 mA output over the same two conductors used for power, reducing field wiring complexity and installation cost compared to 4-wire analyzer systems.

Is this analyzer compatible with existing Yokogawa DO sensors?

The FLXA21-D supports standard Pt1000 (DO30 sensor) and NTC22k (OXYFERM and OXYGOLD sensor) temperature compensation elements, making it compatible with Yokogawa's established dissolved oxygen sensor range.

What if my RFQ model code has an error or typo?

Seven Star LLC's instrumentation division cross-checks every submitted model code against Yokogawa's official configuration tables before confirming an order, catching and correcting typographical errors so the unit delivered matches the customer's actual process requirements.

Is Seven Star LLC an experienced supply partner for Yokogawa products?

Yes, Seven Star LLC is an experienced supplier of Yokogawa in Oman and the GCC, supplying genuine components with full documentation and technical support.

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