The conductivity sensors use a 4-electrode measuring technique that provides accurate readings over a wide range of conductivities and temperatures.  Because the conductivity of ionic solutions increases with increasing temperature, a temperature sensor is also incorporated and is used to provide automatic temperature compensation of 2%/°C normalized to 25°C.  An in-line interface module converts the digital conductivity sensor and temperature data into two separate 4-20mA signals for monitoring with data loggers and PLC devices.

The standard conductivity sensors come with three feet (one meter) of cable between the conductivity sensor and interface module, and 25 feet of marine-grade cable for connecting to recording devices.  Additional cable can extend the length of the conductivity sensor up to 500 feet.  Available conductivity ranges are 0-200µS/cm, 200-2000µS/cm, 2-20mS/cm, 20-200mS/cm and 200-2000mS/cm.  The conductivity sensor’s temperature output has a measurement range of -5°C to +70°C.

Global Water’s GL500-7-2 Conductivity Sensor Recorder adds recording capabilities to the conductivity sensor.  The GL500-7-2 Conductivity Sensor Recorder connects to the conductivity sensor’s 4-20mA outputs to record data.  In addition, Global Water offers the PC320 Conductivity Controller to use the conductivity sensor’s output to control pumps or alarms.

FEATURES

• 4-20mA outputs
• Non-contact measurement means no corrosion
• Outputs raw EC and temperature
• Long term stability
• 3 Year warranty

The EC1500 Electrical Conductivity sensor is specifically suited for low-power water quality applications where access and site visits are limited. Unlike conventional electrode-based cells, the encapsulated toroid design requires very little maintenance, ensuring many years of accurate data collection without recalibration and without deterioration of metals. With all wetted parts made from non-metallic materials, the sensor can be employed to measure in difficult and often corrosive liquids such as seawater and sewerage. An integrated temperature sensor, used for temperature compensation, is configured to provide a separate temperature output.

Applications:

• River/ stream water quality
• Irrigation runoff water quality
• Salinity studies
• Estuary monitoring
• Wastewater quality monitoring
• Aquaculture

Operation Principle

The measurement of the ability of water to carry an electrical current is an indication of the amount of mineral salts in solution. This ability is derived from the presence of charged ion particles, and to a lesser extent, ionization of water itself. Electrical conductivity is nonspecific for a particular salt and all salts present in the solution contribute. The model EC1500 sensor measures conductivity using a pair of magnetically coupled toroid transformers while the solution being measured forms the ‘core’ of the transformer pair. The more conductive the water is, the better the magnetic coupling. This is a non-contact measurement method and is immune to the effects of electrode deterioration.