Measuring electrical conductivity is a very broad and useful method, especially for quality control purposes, so it is important to know how to measure electrical conductivity.
What is electrical conductivity?
Electrical conductivity is the ability of a solution, a metal, or a gas, in short all materials, to conduct electrical current. In solutions, current is carried by cations and anions, while in metals it is carried by electrons. How a solution conducts electricity well depends on several factors:
- Mobility of ions
- The capacity of ions
All materials have a certain degree of electrical conductivity. In aqueous solutions, the level of ionic strength varies from the low conductivity of ultrapure water to the high conductivity of concentrated chemical samples.
The importance of measuring electrical conductivity
Measuring electrical conductivity is a very broad and useful method, especially for quality control purposes. Monitoring the purity of feed water, controlling the quality of drinking water and process water, estimating the total number of ions in a solution, or directly measuring the components in process solutions can all be done using electrical conductivity measurements. The high reliability, sensitivity, and relatively low cost of the instrumentation make it a potential starting point for any good monitoring program. Some applications are measured in units of resistance, reverse conductivity. Other applications require the measurement of total soluble solids (TDS), which is related to conductivity by a factor dependent on the level and type of ions present. Conductivity measurements cover the range of solution conductivity from pure water less than 7-10 S 1 S / cm to values greater than 1 S / cm for concentrated solutions. In general, measuring electrical conductivity is a quick and inexpensive way to determine the ionic strength of a solution. However, this is a non-specific technique that is unable to distinguish between different types of ions and instead offers a reading that fits the combined effect of all available ions.
Measurement of electrical conductivity: –
There are two technical approaches to measuring electrical conductivity – induction and contact.
Induction electrical conductivity measurement:
Induction sensors use two electromagnetic coils, usually enclosed in a polymer ring. An alternating voltage is applied to the actuator coil, which induces voltage in the receiver coil.
The induced current is affected by the electrical conductivity of the solution. Due to the sealed coating, induction sensors can be used in aggressive environments, but they are not suitable for conductivity less than 15 µS / cm.
Contact electrical conductivity measurement:
Contact sensors include electrically conductive electrodes that are in direct contact with the environment. The initial parameters of the measured voltage and current are applied. The interdependence of both parameters, explained by Ohm’s law, makes it possible to calculate the resistance R (measured in ohms [Ω]) or inverse-conductivity G (measured in Siemens [S]).
The contact electrical sensor is usually made up of two electrodes that are insulated from each other. The electrodes, usually made of 316 stainless steel, titanium-palladium or graphite alloy, are specifically sized and spaced to provide a known “cellular constant”. Theoretically, cell constant 1.0 describes two electrodes, each one square centimeter in area and one centimeter apart.
Rose Calibration Company in Melbourne, Australia with over ten years of experience provides all calibration, maintenance, and repair services throughout Australia. If you live in Sydney, Melbourne, Adelaide, Perth, Geelong, and Brisbane, you can receive your quote in less than two hours by fill-up the form via the “Booking” link.