The Electromagnetic Flow Measuring Principle

Summary

Highlights

• The electromagnetic flow measurement principle traces back to Michael Faraday's 1831 discovery. 📚
• Father Bonaventura Thürlemann built the first electromagnetic flowmeter, advancing the practical application of this principle. 🔬
• The operational core involves coils creating a constant magnetic field, aligning charged particles to generate a measurable voltage. 🔄
• Flow meters detect and measure this voltage which is proportional to liquid flow velocity, ensuring precision in measurement. 🎯
• Endress+Hauser employs pulsed direct current to minimize interference, ensuring stability and accuracy in flow measurement. 🔧

Key Takeaways

• Electromagnetic flow meters are inspired by Michael Faraday’s discovery of inducing electric current using a magnetic field in 1831. ⚡️
• Endress+Hauser has positioned itself as a leader with over 1 million electromagnetic flowmeter installations, known for precision and reliability. 💯
• These flow meters provide stable measurements by eliminating interference voltage through pulsed direct current magnetic fields. 🚀
• The principle works by detecting electrical voltage produced as charged particles in the liquid move through a magnetic field. 💡
• It’s applicable for all types of electrically conductive liquids, with easy installation and high accuracy. 🌊

Overview

Chapters

• 00:00 - 00:30: Introduction to Flow Measurement The chapter introduces the concept of flow measurement in piping systems. It highlights the diverse substances transported daily, such as drinking water, fruit juices, chemicals, and slurries with stones.
• 00:30 - 01:00: Electromagnetic Flow Measurement Principle The chapter explains the principle of electromagnetic flow measurement, a method used to measure the flow of fluids through pipes. This method is based on the electromagnetic principle discovered by English physicist Michael Faraday in 1831. Faraday found that an electrical current can be generated using a magnetic field. The chapter emphasizes the need for different measurement principles due to the varying properties of fluids.
• 01:00 - 01:30: Historical Background The chapter "Historical Background" delves into the innovation of the electromagnetic flowmeter developed by Swiss inventor and priest Father Bonaventura Thürlemann. It explains that roughly 100 years later, the knowledge of electrically conductive liquids and their behavior in pipes led to Thürlemann's creation. The flowmeter works using field coils inside the device.
• 01:30 - 02:00: Functioning of Electromagnetic Flowmeters This chapter discusses the functioning of electromagnetic flowmeters. It explains that pole shoes in the device create a constant magnetic field across the measuring tube's cross-section. Two electrodes, positioned at right angles in the tube wall, are important for capturing electrical voltages. Furthermore, an inner lining is mentioned as a crucial component that prevents electrical short circuits between the conductive liquid and the tube, enhancing measurement accuracy.
• 02:00 - 03:00: Principle of Operation In the 'Principle of Operation' chapter, the process of measuring liquid flow using charged particles is described. Initially, with no liquid flow, there is no induced electrical voltage measured between the electrodes as the charged particles are evenly distributed. However, when the liquid starts to flow through the measuring tube, a magnetic field is applied, which then exerts force on the charged particles, affecting their distribution and enabling the flow measurement.
• 03:00 - 04:00: Proportional Voltage and Interference The chapter 'Proportional Voltage and Interference' explains how an electrical voltage is generated and measured in a setup involving liquid separation across a tube wall. This voltage is directly linked to the flow velocity within the pipeline, allowing for the calculation of flow volume when combined with the tube's cross-sectional area.
• 04:00 - 05:00: Pulsed DC Magnetic Field The chapter discusses the relationship between flow velocity and the separation of charged particles, noting that as flow velocity increases, so does the electric voltage between electrodes. It highlights an issue with 'interference voltage' which can affect measurement accuracy. To address this, a solution presented involves generating the magnetic field using a pulsed direct current.
• 05:00 - 06:00: Advantages of Electromagnetic Flowmeters Electromagnetic flowmeters offer distinct advantages due to their ability to alternate the polarity of the magnetic field. This alternating polarity allows any constant interference voltages, such as those arising from electrochemical effects in the liquid or external electromagnetic fields, to be eliminated. Consequently, the effectiveness and accuracy of the measurements are not affected by these interference voltages.
• 06:00 - 07:00: Conclusion The Conclusion chapter highlights the benefits of using Endress+Hauser electromagnetic flowmeters, emphasizing their stability, accuracy, and reliability. With more than 1 million units installed, these instruments ensure high precision and easy installation, reinforcing the company's long-standing commitment to flow measurement expertise and product quality over the past 30 years.

The Electromagnetic Flow Measuring Principle Transcription

• 00:00 - 00:30 The most diverse substances are transported and  distributed in piping systems every single day.   They may include drinking water, fruit juices,  chemicals or even slurries containing stones.
• 00:30 - 01:00 The fluids flowing through pipes often  have completely different properties.   Consequently, there are different  principles for their measurement.  One method is flow measurement based  on the electromagnetic principle. The basic physics of this principle can be traced  back to the English physicist Michael Faraday,   who – in 1831 – discovered that electrical  current can be generated with a magnetic field.
• 01:00 - 01:30 Roughly 100 years later, the  Swiss inventor and priest Father   Bonaventura Thürlemann applied this  knowledge to electrically conductive   liquids flowing in pipes and built the  world’s first electromagnetic flowmeter. Let’s take a closer look at how  this measurement method works! Two field coils are located inside  each electromagnetic flowmeter.
• 01:30 - 02:00 With the help of what are termed  pole shoes, these coils generate a   constant magnetic field over the entire  cross-section of the measuring tube. Two electrodes, which can  pick up electrical voltages,   are installed at a right  angle in the wall of the tube. The lining fitted on the inside  wall prevents electrical short   circuits between the conductive  liquid and the metallic tube.
• 02:00 - 02:30 If there is no liquid flow, no induced electrical   voltage is measured at first  between the two electrodes. The electrically charged particles  of the conductive liquid are evenly   distributed – shown here in water with red and blue particles. However, as soon as the liquid  starts to flow in the measuring tube,   the magnetic field applies a  force to the charged particles. As a result, the positively and  negatively charged particles in
• 02:30 - 03:00 the liquid are separated and collect  on the opposite sides of the tube wall. Now, an electrical voltage forms which is  detected and measured by the two electrodes.  This voltage is directly proportional  to the flow velocity in the pipeline.  Together with the known tube cross-section,  the flow volume can then be calculated.
• 03:00 - 03:30 The greater the flow velocity  – and thus the separation of   the charged particles – the greater the  electrical voltage between the electrodes. The electrodes also detect what is called  “interference voltage” which has to be   separated from the actual measuring signal. One method that has been successfully used for   this purpose is to create the magnetic  field with a pulsed direct current.
• 03:30 - 04:00 To do so, the polarity of the  magnetic field is alternately   reversed – illustrated here in slow motion.  The voltage picked up on the measuring  electrodes now constantly changes in polarity. As a result, all constant interference  voltages can be eliminated – for example,   electrochemical effects in the liquid  or external electromagnetic fields.  Thus, the size of such interference voltages  has no impact whatsoever on the actual measuring
• 04:00 - 04:30 signal. The advantages of this are a stable  measurement and a stable system zero point. With an installed base of over 1  million electromagnetic flowmeters,   Endress+Hauser has stood for flow expertise  and superb product quality for over 30 years.  In other words: high accuracy, easy  installation and absolute reliability.
• 04:30 - 05:00 For all applications, we have the right solution.  Endress+Hauser – your single-source  supplier for measurement technology!