YSI EXO2 Multiparameter Water Quality Sonde

Overview

YSI EXO2 is a multiparameter water quality sonde for continuous, unattended and long-term monitoring. It is the larger member of the EXO sonde platform, with seven ports on the bulkhead: six for smart sensors and one for the central wiper that cleans the optical and conductivity sensors on a schedule. YSI describes the EXO sondes as a versatile and rugged monitoring solution that offers high data quality, reliability during extended deployments and straightforward integration with any monitoring system. YSI is a Xylem brand, and the EXO platform is used for rivers, lakes, reservoirs, estuaries, coastal waters, drinking water sources and industrial discharges.

For operators in Oman and the GCC, the YSI EXO2 is attractive wherever biofouling and heat make frequent site visits expensive. Desalination intakes, brine outfalls, wadi and dam monitoring stations and coastal environmental programmes all need dissolved oxygen, conductivity, temperature, pH and turbidity to be logged over weeks at a time. The sonde fits into the same monitoring family as the instruments already listed by Seven Star LLC, such as the JUMO digiLine O-DO S10 dissolved oxygen sensor, the JUMO ecoLine NTU optical turbidity sensor and the Hach LXV416 LDO2 dissolved oxygen sensor. Seven Star LLC supplies the YSI EXO2 on request with engineering support in Muscat.

Measurement Principle

The YSI EXO2 is a platform for digital smart sensors, so the measurement principle depends on the sensor installed in each port. Dissolved oxygen is measured optically with a replaceable sensor cap, conductivity is measured with a cell that is calibrated for specific conductance and temperature, pH and ORP use electrode modules with replaceable reagent, and turbidity is measured optically in FNU or NTU. Fluorescence sensors measure fDOM, rhodamine and the pigments of total algae, namely chlorophyll with phycocyanin or phycoerythrin, and ion-selective electrodes measure ammonium, chloride and nitrate.

The sonde electronics read each sensor digitally and calculate additional parameters, including salinity, specific conductance, total dissolved solids, total suspended solids, resistivity, water density, vertical position and the percent dissolved oxygen local values. The YSI EXO2 samples at up to 4 Hz, or every 0.25 seconds, and stores the results in an onboard memory that holds more than one million readings. Because the sensors are interchangeable, the same sonde body can be reconfigured when the monitoring question changes.

Engineering Design of the YSI EXO2

The YSI EXO2 has a diameter of 7.62 cm (3.00 inches) and a length of 70.52 cm (27.76 inches) with the guard fitted, and it weighs 3.60 kg without the sensor payload. The sealed body is rated to a depth of 250 metres, or 820 feet, and operates between minus 5 and 50 degrees Celsius. It runs on four D-cell batteries, which YSI quotes at about 90 days with a full sensor payload and a 15-minute logging interval, or on external power of 9 to 16 volts. A fitted central wiper rotates once per logging interval to keep the sensors clean, and an auxiliary port is provided for third-party sensors.

The YSI EXO2 communicates over Bluetooth for wireless setup and over RS-485 on the field cable, and the signal output adapters add RS-232, SDI-12, Modbus and USB. Settings, calibration and deployments are handled with Kor desktop software or the Kor mobile app, and the sonde supports English, Spanish, French, Japanese, German and Chinese. Sensor options include conductivity and temperature, depth, optical dissolved oxygen, fDOM, ISE ammonium, chloride and nitrate, pH, pH and ORP, rhodamine, total algae, turbidity and UV nitrate, and the sonde carries a three-year warranty.

Key Features

The following features make the YSI EXO2 a dependable platform for long-term deployments:

• Seven ports, with six smart sensors and a central wiper, which gives the largest sensor payload of the EXO range.
• Central wiper that cleans the sensors once per logging interval to extend deployments and reduce site visits.
• Four D-cell battery operation for about 90 days, or external power from 9 to 16 volts.
• Memory for more than 1,000,000 logged readings and 512 MB of total memory.
• Bluetooth wireless setup, RS-485 on the field cable, and adapters for RS-232, SDI-12, Modbus and USB.
• Depth rating of 250 metres and sampling at up to 4 Hz.
• Replaceable optical caps and reagent modules that simplify maintenance.
• Three-year warranty and Kor software or mobile app for setup, calibration and data management.

Industrial Applications

YSI positions the YSI EXO2 for continuous monitoring, discrete sampling and systems integration. In Oman that supports source-water monitoring at dams and wadis, seawater intake and brine discharge studies at desalination plants, and compliance monitoring downstream of industrial effluent outfalls at Sohar, Duqm and Salalah. Aquaculture operations along the coast can log dissolved oxygen and temperature continuously, while environmental consultants can deploy the YSI EXO2 on buoys or profiling platforms for coastal baseline studies.

Because the YSI EXO2 can output SDI-12 or Modbus through adapters, it can feed a telemetry system or SCADA network without a separate data logger. Seven Star LLC supplies the sonde with the cables, signal output adapters, sensors, guards, calibration solutions and deployment accessories that a project requires, and our engineers can help select the sensor payload for a given site before an order is placed.

Technical Specifications

The table lists published data for the YSI EXO2 from the YSI EXO sonde specification sheet. Specifications indicate typical performance and are subject to change.

How to Order

To request a formal quotation for the YSI EXO2, tell us the sensor payload, the cable length, the signal output adapter and whether you need battery or external power. Seven Star LLC supplies YSI water quality instruments to customers in Oman and the GCC, with lead time confirmed at quotation, engineering support from our instrumentation division in Muscat, and the specification sheet attached to this page.