The EXO-S series is identical to the original EXO series of water quality sondes, except that they are much shorter, lighter and more affordable. This has been achieved by leaving out the battery compartment. The EXO-S uses the same sensors and accessories as the EXO sonde. They are fully compatible, except for the batteries.

Each multiparameter sonde is rated to a depth of 250 meters. Each sonde contains a number of identical digital sensor ports. The user can select from a large range of available sensors. Each sensor can be plugged in any sensor port of the sonde. The following sensors are available:

• Conductivity/Temperature (includes derived parameters like TDS and salinity)
• Dissolved oxygen (optical)
• NitraLED (UV Nitrate sensor)
• Turbidity (optical, including TSS)
• pH or pH + ORP
• Total Algae (Optical sensor measuring blue-green algae and chlorophyll in one)
• fDOM (optical)
• Ammonium (ISE, fresh water only)
• Chloride (ISE, fresh water only)
• Nitrate (ISE, fresh water only)
• Rhodamine (optical)

Optionally, the sonde can include a pressure sensor for measuring depth. This sensor is included in the sonde’s body and does not use a sensor port.

On the EXO2 and EXO3, an automatic wiper (brush) can be installed in the central sensors port. This wiper will clean all the sensors. This allows for extended deployment periods, even in waters were serious biological fouling occurs.

Smart sondes and sensors
“EXO was designed to be extremely versatile, allowing the user to configure a sonde for different applications in minutes. The key to this versatility is the smart sensors and smart ports,” explains Rob Ellison, YSI Director of R&D. “Each smart port is identical and automatically recognises any EXO sensor, so sensor payloads are designed by the user.”

Monitor without Interruption
No matter which EXO sensors users select, other features of the sensors’ design make them rugged and durable:

• Wet-mateable connectors resist corrosion
• Isolated components prevent short circuits
• Welded housings and double o-rings prevent leaks
• High-impact plastic and titanium resists breaking
• Built-in antifouling systems protect data integrity
• Low power consumption extends underwater deployments

For long-term monitoring programs, the data collected by EXO sensors are compatible with historic data from YSI 6-series sensors, helping users to maintain a consistent record of measurements.

Accuracy
EXO sensors and sondes are tested in a variety of rigorous field conditions, as well as lab conditions, to ensure accuracy and response times. Also, a new metrology system specifically for EXO offers improved accuracy of conductivity and temperature sensors to better address oceanographic challenges.

Dutch market only
Please be informed that we – as a reseller – are only allowed to sell/deliver Xylem/YSI and Xylem/SonTek products to the Dutch market, except when part of a bigger system.