When do you use an EC sensor?
A conductivity sensor is suitable for any application where the ion concentration in a liquid determines process quality. Typical applications include:
- Monitoring of water softeners and reverse osmosis systems
- Control of CIP cleaning cycles in the food industry
- Concentration measurement of acids, alkalis or salt solutions
- Quality control of drinking water, process water or cooling water
- Measurement in air scrubbers to monitor wash solution quality
Choose an EC sensor when you need continuous measurement without sampling and when fast detection of deviations is critical to your process. When a conductivity value falls outside the set range, you can intervene immediately without waiting for laboratory analysis.
How does a conductivity sensor work?
A conductivity sensor measures the resistance of a liquid between two or more electrodes. The more ions the liquid contains, the better it conducts current and the higher the measured conductivity. The measuring principle is based on Ohm's law: conductivity is the reciprocal of the resistance between the electrodes.
Most sensors include built-in temperature compensation, as conductivity is strongly temperature-dependent. Without temperature compensation, measurements at varying process temperatures are unreliable and cannot be compared. Compensation is typically referenced to 25 °C as the standard reference temperature.
For connection to your measurement loop, Ebora supplies conductivity sensors with a 4..20 mA output, suitable for direct integration with your PLC or controller. Also see our range of
pressure sensors and
flowmeters for complete process monitoring.
Conductive or inductive – which type suits your application?
There are two measuring principles for conductivity: conductive and inductive. Each has specific advantages depending on the medium and the measuring range.
Conductive conductivity sensors measure via direct electrode contact with the medium. They are available in 2-electrode and 4-electrode versions. The 4-electrode variant offers better scale compensation and is suited for measurements at very low conductivity values, down to below 100 µS/cm. This is particularly relevant when measuring near-pure water or specific chemicals such as hydrofluoric acid.
Inductive conductivity sensors, also known as toroidal sensors, operate without direct electrode contact. The measuring principle is electromagnetic: two coils induce a current in the medium. Because no electrodes come into contact with the liquid, inductive sensors require less maintenance with dirty or aggressive media, and electrode fouling or corrosion is not a concern.
| Type |
Measuring range |
Suitable for |
Characteristics |
| Conductive 2-electrode |
0.01 µS/cm – 500 mS/cm |
Clean media, hygienic processes, CIP |
Cell constant determines measuring range |
| Conductive 4-electrode |
Down to <100 µS/cm |
Near-pure water, hydrofluoric acid |
Better scale compensation, higher accuracy |
| Inductive (toroidal) |
50 µS/cm – 2000 mS/cm |
Dirty or aggressive media, air scrubbers |
No electrode fouling, low maintenance |
Note for selection: inductive sensors are not suitable for measurements below 50 µS/cm. If you require a low conductivity range, always choose a conductive or 4-electrode version.
Applications by sector
Food industry and pharmaceuticals
Conductive conductivity sensors from Hengesbach are widely used in hygienic processes. The sensor detects the end point of a CIP cycle by measuring when the cleaning agent has been fully flushed out and the product is flowing through the line again. This prevents product contamination and increases process reliability. Hygienic process connections such as Tri-Clamp and DIN 11851 are available as standard.
Air scrubbers and water treatment
The inductive conductivity sensor C6.30 from FIP with 4..20 mA output was developed specifically for use in air scrubbers. The built-in temperature compensation ensures stable measurements at varying ambient temperatures. The same sensor is also used in water treatment installations, cooling towers and softening systems. Thanks to the inductive measuring principle, electrode fouling from limescale or other deposits is not an issue.
Chemical industry and process industry
For aggressive media or heavily contaminated liquids, an inductive sensor offers clear advantages: there is no electrode contact with the medium, which prevents fouling and corrosion. Sensors from Georg Fischer and FIP are available in chemically resistant materials such as PVDF and PP, suitable for measuring acids, alkalis and solvents.
Laboratories and quality control
For accurate measurements at low conductivity values, such as distilled or deionised water, choose a conductive sensor with a low measuring range. The 4-electrode version offers the best accuracy here and is less susceptible to polarisation effects at low ion concentrations.
What to consider when selecting a sensor
When choosing an EC sensor, the following parameters are decisive. A well-matched sensor prevents measurement errors and premature replacement:
- Measuring range: what is the expected conductivity of your medium in µS/cm or mS/cm?
- Medium: clean, dirty, aggressive or hygienic? This determines the measuring principle.
- Temperature: what is the process temperature and is automatic compensation required?
- Installation: insertion length, process connection (e.g. Tri-Clamp, G-thread) and material
- Output: 4..20 mA, digital or other protocols
If you do not know the exact conductivity of your medium, measure first with a portable instrument or ask Ebora for advice based on your process data.
Installation and process connections
A conductivity sensor is typically installed inline, directly in the process pipe or in a bypass. The insertion length and process connection depend on the pipe diameter and process conditions. Common connection types include G1/2, G3/4, G1 male thread and flanged connections for higher pressures.
Hygienic applications have specific requirements for surface finish and connection type. Hengesbach sensors are available with Ra = 0.8 µm and meet the requirements for CIP and SIP applications. During installation, observe the minimum insertion depth to ensure the electrodes are fully surrounded by the medium.
Brands supplied by Ebora
Ebora supplies conductivity sensors from specialist manufacturers for a wide range of applications:
- Hengesbach – conductive sensors for hygienic applications and CIP installations in the food and pharmaceutical industries
- FIP – conductive and inductive sensors (including the C6.30) in chemically resistant plastics for aggressive media and air scrubbers
- Georg Fischer – extensive range for industrial and chemical process monitoring
For related measurement technology, also see our
instrumentation page. Select the right conductivity sensor based on your medium, measuring range and process conditions, or request technical advice directly via our
contact page.
Frequently asked questions
What is the difference between conductivity and resistivity?
Conductivity and resistivity are reciprocals of each other. Conductivity (expressed in µS/cm or mS/cm) indicates how well a liquid conducts electrical current. Resistivity (expressed in MO·cm) indicates how strongly the liquid resists current flow. Resistivity is used for ultrapure water applications; conductivity is the standard measurement unit for process water and chemical solutions.
How often does a conductivity sensor need to be calibrated?
Calibration intervals depend on the medium and application. In clean processes, annual calibration is generally sufficient. For dirty media or critical processes such as CIP endpoint detection, a shorter interval is recommended. Refer to the manufacturer's specifications or contact Ebora for guidance.
What does the cell constant of a conductive sensor mean?
The cell constant (expressed in cm?¹) determines the effective measuring range of a conductive sensor. A low cell constant (e.g. 0.1 cm?¹) is suitable for measurements at low conductivity, such as pure water. A high cell constant (e.g. 10 cm?¹) is intended for highly conductive media such as concentrated salt solutions.
Can a conductivity sensor be installed in a bypass?
Yes, bypass installation is a common solution when inline installation is not possible due to process pressure, pipe diameter or maintenance requirements. In a bypass, the sensor can also be replaced or calibrated more easily without interrupting the process. Contact Ebora for advice on the right installation solution for your situation.
