What Is Electrical Conductivity (EC)?

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Electrical conductivity refers to the ability of water to conduct an electrical current in a solution over a certain distance, usually measured in Siemens (S) per distance. The power for water to conduct electricity comes from the ion concentration within the water, which comes from dissolved solids and inorganic materials like carbonate compounds, chlorides, and sulfides. The conductance level also depends on the ion’s potential to bind with water.

The ability of a material to transmit an electrical current over a certain distance is defined as electrical conductivity or EC. 

Metals usually have a high conductivity, whereas plastics and household ceramics typically have a low conductance level. But, when we discuss liquids (mostly water) electrolytic conductivity has the same principle, but it relies on the ion concentration in the solution to conduct electricity instead of the core material itself. 

Salts or other chemicals (including pollutants) that dissolve into a solution can alter the EC charge; it is the free ions left in the water or solution that can pass an electrical charge. Therefore, EC is highly dependent on ion concentration. 

In this article, you will learn what electrical conductivity is, the applications and industries that rely on electrical conductivity measurements, and how electrical conductivity is monitored and altered. 

What Is EC?

Electrical conductivity (EC) measures the potential of an electrical current to be transported through a material like soil or metal, or a liquid such as water. When EC passes through water, we refer to the process as electrolytic conductivity. 

Electrons can flow through water because of ions dissolved in the water. It is these ions that transport the electrons and electrical charge. 

The concentration of the ions present in water can determine the number of electrons that travel from one electrode (inside an EC probe) to the other. 

The higher the concentration of ions, the greater the flow of electrons, and vice versa. This is why purified water is a poor conductor of electricity; purified water has had most of the ion content removed. 

EC Units Explained…

Scientific units can often be confusing, particularly as electrical conductivity units can vary with the application or industry that you are working with. But do not worry, as it doesn’t matter which industry you are working in or which measurement you use, as all EC measurements determine if the electrical conductance level is too high or too low. 

Saying that, EC units are typically measured in Siemens per distance, often per meter squared per mole (S/m2/mole), millisiemens per centimeter (mS/cm), (microsiemens per centimeter (µs/cm)) or micromhos per centimeter (µmhos/cm). 

The typical conductance ranges (measured in µS/cm) for water are displayed below:

  • Distilled Water: 0.5-3 
  • Tap Water: 50-800 
  • Potable Water (US standards): 30-1,500 
  • Freshwater Streams: 100-2,000 
  • Industrial Wastewater: 10,000
  • Seawater: 55,000 

Why Is EC Measured?

It is essential to measure conductivity in the following industries and applications:

  • Hydroponic systems
  • Drinking water and wastewater
  • Brewing beverages like beer and packaging milk 
  • Laboratory and medical equipment
  • Agricultural applications
  • Scientific research and measuring seawater (oceanographers)
  • Metal manufacturing

EC In Hydroponics & Agriculture

In hydroponics, measuring EC gives you a detailed explanation of what is happening within your soil and nutrient feed. Over time, the EC value will either fluctuate up or down, or it will stay the same, which is why electrical conductivity should be measured regularly. 

Electrical conductivity values for hydroponic nutrient solutions should range from 0.5 to 2 mS/cm. However, particular plant crops will have preferred EC ranges to grow and thrive. Always check the specific EC requirements for the crop you are growing. 

Electrical conductivity is critical because if the EC falls outside the ‘desired’ range, your plants/crops will soon show signs of poor plant health. These can be anything from stunted growth to leaf necrosis. 

Drinking Water & Wastewater 

Electrical conductivity measurements are used to remove and control contaminants and impurities in drinking water and wastewater systems. 

Wastewater treatment facilities rely on measuring electrical conductivity to control which treatment process will be the most successful to remove contaminants and impurities. In wastewater treatment facilities, changes in electrical conductivity indicate that pollutants are present in the water. Although measuring EC cannot tell us what type of pollutant is in the water, it will identify that there is an issue. 

What Causes High EC In Water?

Reasons For Low EC In Water

  • Excessive nutrient absorption

EC Importance In Beverage Industries

Conductivity measurements are a critical component in the design of clean-in-place (CIP) systems. They are used widely in dairy and alcoholic CIP systems to determine how effectively equipment that comes into contact with the product or solution has been cleaned and flushed. 

Conductivity in CIP notices changes in the EC of a sample stream to indicate when the flushing process starts and finishes. During the CIP rinse cycle, low conductivity values indicate that all chemicals in the process stream have been flushed out, and it is ready for the next batch of product. Without EC in CIP systems, harmful cleaning products could potentially come into contact with humans, causing issues for human health, and putting businesses at risk of a health and safety breach.

Laboratories & Medical Equipment

The most common use of EC in labs and medical facilities is also in CIP systems during cleaning maintenance in IV and other body fluid tubing. According to studies in the last decade, EC has also been useful in effectively measuring the precise amount of blood present in dry blood spot analysis. This advance in EC technology has provided a new way to measure sodium levels in a patient’s blood. 

Oceanography Studies & Research

Oceanographers (ocean scientists) measure conductivity on a daily basis to see how many dissolved substances, chemicals, and minerals are present in seawater. When there are higher amounts of these impurities in the water, a higher electrical conductivity is usually measured. 

EC & Manufacturing Metals

Companies that manufacture or sell metal products (like jewelry or metal infrastructures), use EC to verify the authenticity of aluminum, copper, or gold. Measuring the EC can also identify the metal material’s purity, strength, and integrity, all of which are essential in how durable the end product will be.

Other industries that utilize EC measurements include

  • Automotive
  • Electrical power industries
  • Oil, gas, and petrochemical applications
  • Aerospace
  • Electronics 

Measuring EC

Monitoring EC is important to understand water quality, nutrition monitoring, and during health and safety testing, therefore, EC testing should be completed daily, as things can easily change from one day to another. Daily testing allows you to detect issues before they arise into a larger problem.

Electrical conductivity is measured using a conductivity meter and probe. A voltage is applied between two electrodes inside the probe once immersed inside a sample or solution. The resistance of the water (or material) causes a drop in the voltage, which is then used to calculate the conductivity. 

The EC values are calculated and displayed on a screen which is then plotted onto a graph, so that daily, weekly, monthly, or yearly trends can be identified. 

Tips for accurate EC measurements:

  • Regularly clean the EC probe
  • Calibrate the EC probe periodically using a standard EC calibration solution – If you are unsure how to calibrate your EC meter, read our guidelines here
  • Check the battery is not low, as this can cause errors 
  • Always store the EC probe correctly, in a cool, dry place
  • Always allow plenty of time for the conductivity meter to equilibrate to the same temperature as the sample

You must also understand and anticipate how temperature affects conductivity measurements.

Lowering EC In Water

To reduce the conductivity in water, the number of total dissolved solids (TDS) needs to be removed either by an ion exchanger like flocculation, reverse osmosis (RO), or distillation.

To lower electrical conductivity in water, a pH-balanced solution can be added to dilute the concentration of salts – in hydroponics, pH-balanced water can easily be added to the water reservoir. 

If the EC level is very high, you may consider completely flushing out your system, rinsing roots if you are working with crops or plants, or topping up your system with a low-strength nutrient solution to displace ions.

To lower the EC in soils, the idea is the same in that dilution with pH-balanced water is added. For potted plants, add the water until they start to drain and measure the EC runoff. Compare the EC run-off reading with the original root zone EC value to confirm that you have flushed enough salts out of the soil. 

Raising EC In Water

To raise the EC in water and soil, a nutrient solution, fertilizer, or an additive is added. After treating the water or soil, test the EC again to avoid overdosing.

Spooning salt into a glass of water

If you are ever unsure how to alter the EC in hydroponic systems, always speak to an expert. 

Summary

Electrical conductivity or EC is a physically quantifiable measurement that plays a crucial role in many industrial processes – primarily hydroponics, drinking water, and wastewater systems.

Electrical conductivity refers to the ability of water to conduct an electrical current in a solution over a certain distance, typically measured in Siemens (S) per distance. The power for water or a solution to conduct electricity comes from the ion concentration within the water. 
If you are eager to learn more about electrical conductivity, or what electrical testing equipment we have to offer, do not hesitate to contact our world-class team at Atlas Scientific, we are always happy to help with any testing needs you may have!

Conductivity Probes & Circuits

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