The Electromagnetic Flow Measuring Principle

Summary

This video explains the principle behind electromagnetic flow measurement, a method used to measure the flow of various substances through pipes, from drinking water to chemicals. Based on Michael Faraday's discovery of generating electricity through magnetic fields, it details how an electromagnetic flowmeter works, with field coils generating a magnetic field and electrodes detecting voltage caused by flowing conductive liquids. The video also covers interference voltage elimination for stable measurements and highlights Endress+Hauser’s expertise and reliability in providing high-accuracy, easy-to-install flowmeters for diverse applications.

Takeaways

• 😀 The most diverse substances are transported through piping systems, including drinking water, chemicals, and slurries.
• 😀 Fluids flowing through pipes have different properties, which requires various measurement principles.
• 😀 Flow measurement based on the electromagnetic principle is one of the methods used for fluid measurement.
• 😀 Michael Faraday discovered in 1831 that electrical current can be generated with a magnetic field, which forms the basis for electromagnetic flowmeters.
• 😀 In the early 20th century, Father Bonaventura Thürlemann applied Faraday’s principle to build the world’s first electromagnetic flowmeter.
• 😀 An electromagnetic flowmeter has two field coils that generate a constant magnetic field over the cross-section of the measuring tube.
• 😀 Two electrodes, installed at a right angle in the tube wall, pick up electrical voltages caused by the flow of conductive liquids.
• 😀 When the liquid flows through the pipe, the magnetic field separates positively and negatively charged particles, creating a measurable electrical voltage.
• 😀 The voltage detected by the electrodes is directly proportional to the flow velocity, which helps calculate the flow volume.
• 😀 Interference voltages, such as electrochemical effects or external electromagnetic fields, are filtered out using pulsed direct current to ensure accurate measurements.
• 😀 Endress+Hauser has been a leader in electromagnetic flowmeters for over 30 years, with over 1 million units installed, offering high accuracy, easy installation, and reliability.

Q & A

What substances are commonly transported through piping systems?

Piping systems transport a variety of substances, including drinking water, fruit juices, chemicals, and slurries containing stones.

Why are there different principles for measuring the flow of fluids in pipes?

The fluids flowing through pipes can have completely different properties, which requires different measurement methods to accurately assess the flow.

What is the principle behind electromagnetic flow measurement?

Electromagnetic flow measurement works based on the principle discovered by Michael Faraday, where an electrical current is generated by a magnetic field moving through a conductor.

Who applied the electromagnetic principle to measure liquid flow in pipes?

Father Bonaventura Thürlemann, a Swiss inventor and priest, applied the electromagnetic principle to electrically conductive liquids flowing in pipes, creating the world’s first electromagnetic flowmeter.

How does an electromagnetic flowmeter work?

An electromagnetic flowmeter uses two field coils to generate a magnetic field across the measuring tube. Electrodes installed at right angles in the tube wall measure the electrical voltage induced by charged particles in the fluid.

What happens when there is no liquid flow in an electromagnetic flowmeter?

When there is no liquid flow, no induced electrical voltage is measured, and the electrically charged particles of the conductive liquid are evenly distributed.

What occurs when the liquid starts to flow in the measuring tube?

As the liquid flows, the magnetic field applies a force to the charged particles, separating them into positive and negative particles, which collect on opposite sides of the tube, generating an electrical voltage.

How is the flow volume calculated in an electromagnetic flowmeter?

The electrical voltage detected by the electrodes is directly proportional to the flow velocity in the pipeline. By knowing the tube’s cross-section, the flow volume can be calculated.

What is ‘interference voltage’, and how is it dealt with in flow measurement?

Interference voltage is unwanted electrical noise that can affect measurements. It is eliminated by using pulsed direct current, which alternately reverses the polarity of the magnetic field, ensuring stable and accurate measurements.

What are the advantages of using pulsed direct current in electromagnetic flowmeters?

Using pulsed direct current to reverse the polarity of the magnetic field helps eliminate constant interference voltages, such as electrochemical effects or external electromagnetic fields, ensuring stable measurements and a reliable system zero point.