Conductivity refers to the ability of a certain material to conduct electricity. It is measured in Siemens per meter and is commonly represented with the use of the Greek letter σ. Electric current can easily flow through a material that has high conductivity.
In order to carry an electrical current, a particular solution must contain ions or changed particles. Many conductivity measurements are actually made in aqueous solutions, and the ions that cause conductivity come from electrolytes that are dissolved in the water. Some examples of electrolytes include acids, such as acetic acid and hydrochloric acid, sales, such as magnesium sulfate and sodium chloride and bases, including ammonia and sodium hydroxide. While water itself isn’t an electrolyte, it has a small conductivity, which means that water contains at least some amount of ions.
How is Conductivity Used?
Conductivity has a variety of applications. Conductivity measurements are even used in a wide variety of industries. Its common applications include the following:
Lead Detection: The water used for cooling in surface condensers and heat exchangers often contain a huge amount of dissolved ionic solid. Any leakage of cooling water into the process liquid can lead to dangerous contamination. In order to detect leaks in an easy and effective manner, conductivity is measured in the condenser hot-well or in the outlet of a heat exchanger.
Treat Water: Raw water or tap-water, river or lake water is not always suitable for industrial use. Contaminants, mainly ionic are contained in the water, and if it’s not removed, scaling and corrosion in plant equipment can occur. This is particularly true in cooling towers, boilers and heat exchangers.
There is a variety of ways to treat water and every treatment has its own goal. However, the goal is often demineralization, which refers to the removal of nearly all, if not all the contaminants. Since conductivity is a measure of the complete ion concentration, it is recommended to monitor the performance of the demineralizer. However, it is important to note that it’s not really suitable to measure how well certain ionic contaminants are removed.
Also, conductivity is used to examine the build-up of dissolved ionic solids in boilers and evaporative cooling water systems. If the conductivity gets extremely high, it means that there is a potentially dangerous accumulation of solid. This would cause the quantity of water to be drained out of the system and then replaced with water with lower conductivity.
In addition, in the food and beverage industries, as well as in the pharmaceutical industry, vessels and piping are cleaned and sanitized periodically in a procedure known as Clean in Place or CIP. Conductivity is applied in order to monitor the CIP solution’s concentration, often sodium hydroxide and the rinse completeness.
Even though conductivity is non-specific, if particular conditions are met, it can be utilized to measure the CIP chemicals concentration, as well as the concentration of caustic and acid solutions used to regenerate ion exchange de-mineralisers.
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