Electrical Conductivity Sensors

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Conductivity is the measurement of the ability of a solution to carry an electric current. It is defined as the inverse of resistance (Ohms) per unit square and is measured in units of Siemens/metre or micro-Siemens/centimetre.

The measurement of conductivity is necessary for the determination of a solutions salt content (the salinity). Salinity is proportional to conductivity and is expressed in terms of the concentration of salt per unit volume (mg/l, ppt, etc).

Electrical conductivity readings are a function of the number of ions present and their mobility. The electrical conductivity of a liquid changes at a rate of approximately 2%/^oC for neutral salt and is due to the ion mobility being temperature dependant. The temperature coefficient of conductance (or the K factor) varies for salts and can be in the range of 0.5 to 3.0.

As EC is a function of both salt concentration and temperature, it is preferable to normalise a conductivity measurement to a specific reference temperature (25oC) in order to separate EC changes due to salt concentration from those due to temperature changes.

Conductivity and Temperature are two of the most common water related parameters measured by scientists and engineers for assessment and research purposes. EC Sensor utilise a unique combination of advanced features including:

• Toroidal sensing technology.
• On-board temperature measurement.
• Microprocessor technology controlling temperature compensation, linearisation and enabling field calibration adjustments.
• Seperate conductivity and temperature outputs.
• Raw conductivity or on-board normalisation of conductivity to 25^oC over a 0-30^oC range.
• Optional on-board data logger.
• Optional Delrin casing for harsh environments.

The EC Sensor combines robust, sealed construction with an electrode-less sensing system to offer unparalleled reliability. Designed for low power consumption, the sensor can be operated from remote power sources for extended periods. Field experience has shown that the EC Sensor can be left unattended for up to six months. The high reliability of sensors means critical measurements are not lost through sensor down time. Time wasting, unscheduled site visits are therefore minimised.

Field conductivity measurements in ionised solutions have traditionally been fraught with inaccuracy due to temperature and electrode effects. The Electrical Conductivity Sensors substantially eliminate these conventional sources of error. A large sized toroidal sensor element uses the free ions in solution as a conductive path between two shielded ferrite transformer cores. This system eliminates errors caused by electrode degradation. An advanced compensation algorithm in the on-board microprocessor substantially reduces system non-linearity and temperature drift errors.

The Electrical Conductivity Sensor EC250 offers a unique combination of advanced features:

• Toroidal sensing technology eliminates electrode corrosion effects guaranteeing long life and reduced field servicing.
• On-board temperature measurement and microprocessor controlled temperature compensation and linearisation ensure highly accurate readings in demanding conditions.
• Senor can be field calibrated with easy to use state of the art graphical calibration software.
• Separate conductivity and temperature outputs deliver raw conductivity or on-board normalisation of conductivity to 25^oC.
• Optional on-board data logger with sophisticated logging features enables unattended operation for months at a time.

Intelligent Electrical Conductivity Sensor model EC350 is a complete, self-contained electrical conductivity measurement and data logging system. The EC350 adds sophisticated and versatile data acquisition, control and communications capabilities to standard EC250 Electrical Conductivity Sensor. Standard features of the EC350 include:

• RS232 output.
• In-built logger.
• 0.5MB standard memory.
• Storage of measured data within the sensor for long periods.
• Easy configuration of logging parameters and uploading of logged data.
• Automatic transfer of data to a central office simply by attaching a data modem and mobile phone.
• Improved linearity and accuracy through the use of microprocessor based compensation.
• Facility to set alarm conditions which can trigger additional monitoring equipment such as water samplers.
• Lithium battery pack option for fully self-contained operation.

Sophisticated communication features in the EC350 make remote site logging of water pressure or depth easier than ever. In combination with an external data modem and mobile phone, the EC350 enables remote uploading of logged data and reprogramming of logging schedules. In addition the EC350 can respond to user-programmed alarm conditions by triggering an associated sensor or by calling one of the four preset phone numbers with a user-programmed alarm message.

The EC350 can be powered using external batteries (via the sensor cable) or with optional lithium battery pack, which can be fitted as an extension to the sensor body, making a fully self-contained measurement and logging system.

The EC350 can be supplied with a built-in pressure sensor to provide a complete river level and conductivity data logger in one sophisticated and elegant package.

Price:.....$2,500.00