What is a Torordial Conductivity Sensor?
Conductivity sensors come in many shapes and sizes. So, when is the right time to use a toroidal conductivity sensor? First, you must choose your conductivity sensor based on the composition of the liquid you are analyzing and the purpose of the measurement.
An inductive or toroidal conductivity sensor might also be called “non-contacting.” This term is because the technology does not involve electrodes in direct contact with the process. Instead, a corrosion-resistant plastic body encapsulated two tightly wound toroids.
The first toroid acts as the “drive” coil, and an alternating voltage is applied. This induces a voltage in the surrounding liquid, which causes an ionic current to flow proportional to the conductance of the liquid. The second coil is the “receive” coil. It then transfers the ionic current into an electric current, and your transmitter measures this current.
Why use a Torordial Conductivity Probe?
There are four main reasons you should consider using a toroidal conductivity probe. These include your measuring range, corrosion, buildup, and concentration.
1. Wide Measuring Range
Due to design and function, toroidal sensors commonly have a measuring range of 0 to 2000 mS/cm. This range is suitable for applications ranging from drinking water to heavily polluted media. The only time to avoid toroidal sensors is when you require high resolution and accuracy in high purity water applications. Therefore, you can use one sensor type for many applications!
2. Corrosion Resistant
Toroidal conductivity sensors typically have plastic wetted components. Materials of construction can range from Polypropylene to more resistant plastics like PFA. This sensor material is appropriate for corrosive applications. They are also ideal for hygienic applications due to their durability in CIP and SIP services.
3. Buildup Resistant
The toroidal “doughnut” design, non-contact operation, and smooth plastic finish make it ideal for use in heavily polluted, scaling, and oily media. Significant buildup would need to occur to influence the measurement. Furthermore, toroidal conductivity probes are ideal for measuring slurries and in industrial wastewater applications.
4. Acid/Base Concentration Measurement
Most conductivity transmitters can take a conductivity value from a toroidal sensor and then provide a calculated concentration measurement. With a wide measurement range and corrosion-resistant surface, toroidal sensors are commonly used for measuring spent caustic concentration in cleaning systems as well as acid concentration on a steel production pickling line. Many other applications are possible using this technology.
