Magnetic Flow Meters

Magnetic flow meters can be easily applied in lined
pipe sections and those of substantial diameter.
Image courtesy Yokogawa

The measurement of fluid flow is a common process control function. Flow measurement can have a range of differing output requirements, depending upon the needs of the process operators. With many technologies and instruments from which to choose, knowledge of the principals behind each measurement technology and basic operation requirements can help in the selection of the best instrument for each application. 

Anywhere there are pipes, somebody wants to know how much fluid is passing through them. Industrial flow meters rely on their ability to measure the change in some physical characteristic of fluid moving within a pipe that can be related to fluid velocity or mass flow. Depending upon the nature of the raw measurement, additional information and processing may be necessary to convert the base measurement into a useful measurement of flow rate.

In the processing industries, differing technologies are used to measure fluid motion. Some common technologies include magnetic, ultrasonic, vortex shedding, Coriolis and differential pressure. This list is not exhaustive, and several other technologies will certainly be found in use. Each methodology survives within a competitive marketplace due to its unique combination of performance and value attributes. Let's look at magnetic flow meters, also referred to as magmeters.

The operational principle of a magnetic flow meter is based upon Faraday’s Law. This fundamental scientific principle states that a voltage will be induced across a conductor moving at a right angle through a magnetic field, with the voltage being proportional to the velocity of the conductor. The principle allows for an inherently hard-to-measure aspect of a conductive fluid to be expressed via the magmeter. In a magmeter application, the instrument produces the magnetic field referred to in Faraday’s Law. The conductor, moving at a right angle to the magnetic field, is the fluid. The actual measurement of a magnetic flow meter is the induced voltage corresponding to fluid velocity. This can be used to determine volumetric flow and mass flow when combined with values of other fluid properties and the pipe cross sectional area. Magnetic flow meters enjoy some positive application attributes.

• Magnetic flow meters have no moving parts.
• The instrument, which often resembles a pipe section, can be lined with corrosion resistant material for use with aggressive media.
• With no sensor insertions or obstructions in the fluid path, the impact of the instrument on the flow is minimal.
• Accuracy, when compared to other technologies, is high.
• Application to laminar, turbulent, and transitional flow profiles is permissible.
• Generally, measurement is not adversely impacted by fluid viscosity, specific gravity, temperature and pressure.
• Magnetic flow meter technology can be applied to a very wide range of pipe sizes.
• Device responds rapidly to changes in fluid flow.
• Can be successfully applied to liquids containing heavy particulates.
• Generally long service life with little maintenance.

Though the roster of positive attributes is strong, magmeters are not universally applied. Consider some of these points with respect to your potential application.

• The fluid acts as the "conductor", as stated in Faraday's Law. Magnetic flow meters only work on liquids with conductivity above a certain threshold. They may be unsuitable for use with hydrocarbons and high purity water for this reason.
• Cannot be used to measure gas flow because gases are not sufficiently conductive.
• Piping must be grounded.
• Generally, rated accuracy requires the pipe cross section to be filled by the liquid being measured.

This listing of attributes is very general in nature. Some magnetic flow meter variants have adaptations that minimize or accommodate the impact of special process conditions. Share your flow measurement requirements and challenges with a process measurement specialist. Your own knowledge and experience will be leveraged into an effective solution by their product application expertise.

Industrial Fluid Flow Measurement

Coriolis flow meters deliver a mass flow measurement
Image courtesy Yokogawa

Fluid flow measurement is commonly employed in many industrial process control operations. Accurate and useful flow measurement can be obtained with the proper application and installation of a flow meter as part of the fluid transfer system.

Industrial flow meters employ differing technologies to directly or indirectly measure gas and liquid flow rates. The selection of an appropriate measurement technology and instrument will be influenced by a number of factors related to the installation and application demands.

Among the many available technologies for fluid flow measurement, vortex flow meters, magnetic flow meters, Coriolis flow meters, and rotameters are among some of the most common found in industry.

Each of the separate technologies have attributes which can make them more suitable to certain applications. Selecting the most appropriate flow measurement technology for an application is one of the initial and crucial steps to designing a well functioning flow measurement system.
Selection criteria, such as fluid temperature, pressure, and velocity will be part of the selection process. Additional considerations include whether the fluid may be abrasive, corrosive, clean or dirty. The state of the fluid, liquid or gas, must also be considered. The desired output, whether volumetric or mass flow, will certainly be an integral part of the criteria.

Selecting the right measurement technology and instrument is not always an easy task, especially since it may be something that you do infrequently. Share your flow measurement challenges and requirements with process instrumentation specialists, leveraging your own knowledge and experience with their product application expertise to save time and develop an effective solution.

Smart Output™ Module For Water System Monitoring

Full bore flanged and insertion style magnetic flowmeters,
with Smart Output™ technology to enhance their functionality.
Image courtesy McCrometer 

Water distribution systems, though mostly invisible to the general public, are highly complex infrastructure arrangements that extend to a very large number of locations throughout a service area. Monitoring the activity and operational health of the distribution system, key to maintaining high levels of efficiency and service, requires measurement instrumentation installed throughout the system.

Magnetic flowmeters are an integral part of water system instrumentation. Their advantages for use in water systems were outlined in a previous article on how magnetic flowmeters work. McCrometer is an innovator in the design and manufacture of magnetic flowmeters for water system flow measurement. Their Smart Output™ technology is available for use with full bore flanged and insertion style flowmeters to provide the information needed for modern water system operation.

• AC or DC powered versions
• Compatible with Sensus and Itron smart water networks
• Enables networking of water meters throughout distribution system
• Queries, diagnostics, and data transfer can be scheduled or on demand
• Enables AMR (Automatic Meter Reading) and AMI (Advanced Metering Infrastructure)

The Smart Output™ function is an additional module included as part of the instrument transmitter. 

More information is available from product application specialists, with whom you should share your flow measurement challenges of all types. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.

Maintenance Procedures - Yokogawa ADMAG TI Series AXW Magnetic Flowmeter

The AXW series of magnetic flow meters is available in
a range of sizes with corrosion resistant lining.
Image courtesy Yokogawa

The ADMAG AXW™ series of magnetic flow meters has been developed based on Yokogawa's decades of experience in the design and manufacture of magnetic flowmeters. The AXW series continues the tradition of high quality and reliability that has become synonymous with the Yokogawa name.

The AXW series is ideal for industrial process lines, and water supply and sewage applications. With outstanding reliability and ease of operation, developed on decades of field-proven experience, the AXW will increase user benefits while reducing total cost of ownership.

Magnetic flow meters, also called electromagnetic flow meters or "magmeters", operate on a very simple principal. An electrically conductive liquid moving through a magnetic field will generate a voltage that is related to the velocity of the liquid. Magnetic flow meters have no moving parts and present little to no pressure drop to the piping system into which they are installed.

Sizes are available from 500 to 1800 mm (20 to 72 inch.) with a wide liner selection such as PTFE, natural hard rubber, natural soft rubber, and polyurethane rubber. The line accommodates industry standard process connections such as ASME, AWWA, EN, JIS, and AS flange standards. A submersible version is also available.

Care and maintenance for magnetic flow measurement devices is simple and minimal. The manual included below provides basic guidelines for maintenance procedures of ADMAG TI (Total Insight) Series AXW magnetic flowmeters. Share your flow measurement challenges with process instrument specialists, leveraging your own knowledge and experience with their product application expertise.

Maintenance Procedures for Yokogawa ADMAG TI Series AXW Magnetic Flow Meter from Miller Energy, Inc.

Magnetic Flowmeters: Principles and Applications

Magnetic flowmeters are well suited for flow measurement
with conductive fluids.
Image courtesy Yokogawa

Fluid process control operations rely on the operator's ability to accurately determine qualities and quantities of liquid or gaseous materials. In terms of appraising and working with fluids (such as liquids, steam, and gases) the flowmeter is a staple tool, with the simple goal of expressing the delivery of a subject fluid in a quantified manner. Measurement of media flow velocity can be used, along with other inputs, to determine volumetric or mass flow. The magnetic flowmeter, also called a magmeter, is one of several technologies used to measure fluid flow.

In general, magnetic flowmeters are sturdy, reliable devices able to withstand hazardous environments while returning accurate measurements to operators of a wide variety of processes. The magnetic flowmeter has no moving parts. The operational principle of the device is powered by Faraday’s Law, a fundamental scientific principle stating that a voltage will be induced across any conductor moving at a right angle through a magnetic field, with the voltage being proportional to the velocity of the conductor. The principle allows for an inherently hard-to-measure quality of a substance to be expressed via the magmeter. In a magmeter application, the meter produces the magnetic field referred to in Faraday’s Law. The conductor is the fluid. The actual measurement of a magnetic flowmeter is the induced voltage corresponding to fluid velocity. This can be used to determine volumetric flow and mass flow when combined with other measurements.

The magnetic flowmeter technology is not impacted by temperature, pressure, or density of the subject fluid. It is however, necessary to fill the entire cross section of the pipe in order to derive useful volumetric flow measurements. Faraday’s Law relies on conductivity, so the fluid being measured has to be electrically conductive. Many hydrocarbons are not sufficiently conductive for a flow measurement using this method, nor are gases. On the other hand, water and aqueous solutions tend to exhibit sufficient conductivity to apply magmeter technology.

Magmeters apply Faraday’s law by using two charged magnetic coils; fluid passes through the magnetic field produced by the coils. A precise measurement of the voltage generated in the fluid will be proportional to fluid velocity. The relationship between voltage and flow is theoretically a linear expression, yet some outside factors may present barriers and complications in the interaction of the instrument with the subject fluid. These complications include a higher amount of voltage in the liquid being processed, and coupling issues between the signal circuit, power source, and/or connective leads of both an inductive and capacitive nature.

In addition to salient factors such as price, accuracy, ease of use, and the size-scale of the flowmeter in relation to the fluid system, there are multiple reasons why magmeters are the unit of choice for certain applications. They are resistant to corrosion, and can provide accurate measurement of dirty fluids – making them suitable for wastewater measurement. As mentioned, there are no moving parts in a magmeter, keeping maintenance to a minimum. Power requirements are also low. Instruments are available in a wide range of configurations, sizes, and construction materials to accommodate various process installation requirements.

As with all process measurement instruments, proper selection, configuration, and installation are the real keys to a successful project. Share your flow measurement challenges of all types with a process measurement specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Yokogawa ROTAMASS "Total Insight" Line of Coriolis Flowmeters

In the last decade, the use of Coriolis flow meters has been changing from general purpose to supporting customer needs in specific applications. While the technological complexity increased, the demand for simple operation and handling also grew.

Yokogawa answers these needs by offering six dedicated product lines with two specialized transmitters allowing the highest flexibility - the ROTAMASS Total Insight.

Total Insight

The ROTAMASS philosophy gives Total Insight throughout the whole lifecycle.

To facilitate the implementation of optimal processes and increase the efficiency of personnel, Yokogawa has placed a strong focus on simplifying fundamental operating concepts with Total Insight. The Total Insight concept is built in to the latest generation of Rotamass transmitters and provides enhanced settings for customized setups, predefined trend views, or multiple configuration sets for fast changeover in batch production.

ROTAMASS NANO - When every drop counts

The world's smallest dual bent tube Coriolis flow meter series for highly accurate measurement at lowest flows.

The dual tube design compensates for fluctuations of density, temperature, pressure and environment conditions. This provides a consistent repeatable and accurate measurement especially for small size Coriolis flow meters.

Typical Applications

• Batching
• Dosing
• Blending
• Chemical injection
• Dosing systems
• High pressure gases
• Liquid and gas low flow measurement
• Precision coatings
• Metering pump control
• Metrology
• R&D laboratory
• Vacuum thin film coating

ROTAMASS Prime - Versatile in applications

The favorably priced and versatile Coriolis flow meter with lowest pressure drop in the market. Ideal for a broad range of standard applications, this series is a flexible and cost effective solution for highly accurate flow and density measurements.
Features such as concentration measurement or the Tube Health Check function allow the meter to be adjusted to customer needs.

• Typical Applications
• Batching
• Blending
• Chemical recovery
• Continuous reaction
• In-line concentration and density measurement
• Catalyst feed
• Filling and dosing
• Mass balance
• Net oil computing
• Palm oil
• Process control

ROTAMASS Supreme - Experience meets innovation

The most accurate Coriolis flow meter with industry’s best zero stability.

The successful Rotamass series has been progressively developed and is also newly equipped with

the latest technology. This meter delivers unsurpassed performance for demanding and critical applications with superior aeration handling and advanced diagnostic functionality.

• Typical Applications
• Batching
• Burner control
• Feed and product control
• Filling and dosing
• Gas void fraction
• In-line concentration and density
• Loss control
• Material and mass balance
• Net oil computing
• Process control
• Solvents
• Water cut

ROTAMASS Intense - Safe under high pressure

The Coriolis meter with the most robust and durable design for precise measurement in high pressure applications.

Safety is always a concern and especially when operating at high pressures. Therefore, this series has been designed to meet the highest safety requirements. Combined with advanced diagnosis such as the “Total Health Check” function, operation is always under secure control.

• Typical Applications
• Chemical injection
• Compressed gases
• Fuels
• Glycol TEG/MEG
• High pressure gases
• Hydraulic oil
• Hydrocarbons
• Liquified gases
• Natural gas hydration
• Offshore and onshore
• Oil refinery processes
• Solvents

ROTAMASS Hygienic - With pure dedication

Specifically designed and certified for food & beverage, biotechnology and pharmaceutical utility applications.

This series is the appropriate answer to the daily constraints of hygienic processes ensuring continuous product quality and minimizing losses. This is made easy by the provided multi-variable measurement and various dedicated features.

• Typical Applications
• Bioreactor feeds
• Bottling
• Carbonation of beverages
• Deionized water
• Fermentation
• Juice processing
• Molasses measurement
• Online sugar concentration
• Raw milk tanker unloading
• Process water reclamation
• Product quality control
• Sugar industry

ROTAMASS Giga - Big in performance

Delivering best in class accuracy and most flexible installation at high flow rates.

The unmatched accuracy at the low end of the measuring range offers maximum flexibility from engineering to final operation. This series unifies a long service life with low maintenance costs and reliable performance.

• Typical Applications
• Bitumen
• Distribution networks
• Drilling mud
• LNG
• Rail car loading
• Ship loading
• Truck loading
• Tar
• Offshore and onshore
• Oil well cementing and hydrofracturing

Essential and Ultimate Transmitters

Future Ready. The ROTAMASS TI product family has a common and unified transmitter platform with two options that provide the highest flexibility and a tailor-made solution. The Essential transmitter is the cost effective solution for general purpose applications, and the Ultimate transmitter provides various additional features for best-in-class measurement.

Essential Transmitter

• Wizard for easy setup and guidance through the main configuration
• “Event Management” as unique and useful support to run the process effectively and safely
• Data mobility provided by microSD card for easy transfer to other devices for fast setup or to pc for in-depth process analysis or remote service
• Widest range of I/O combinations in the market for most flexible adjustment to the existing system periphery
• Universal power supply to install the device anywhere in the world
• HART communication

Ultimate Transmitter

• Patented “Tube Integrity” function and “TotalHealth Check” for inline meter verification without disturbing running measurements
• “Features on demand” for easy expansion of special functions via software activation key
• Batching function combined with multiple configuration sets to support fast changeover
• “Dynamic Pressure Compensation” for consistently accurate and stable measurement even with significant fluctuations in operating pressures
• Inline concentration measurement
• Integrated net oil computing acc. API standard

Share your process flow measurement requirements and challenges with application experts, combining your own experience and knowledge with their product application expertise to develop effective solutions.

V-Cone® Flow Meter Conditions Flow For Accurate Measurement

Accurate measurement of fluid flow is a process requirement in many industrial operations. There are numerous methods employed in the measurement of fluid flow, of which the McCrometer V-Cone® is one entry with very particular advantages. Whether the application involves liquid, steam, or gas, this flow meter design, with its own flow conditioning built in, provides exceptional differential pressure flow measurements in a space saving format.

The video provides a clear illustration of how the V-Cone® design conditions fluid flow in order to provide better DP measurement performance. Share your flow measurement challenges with application specialists, combining your process expertise with their depth of product application knowledge to develop effective solutions.

Magnetic Flow Meter – When Is It the Right Selection for Your Project?

Industrial Magnetic Flow Meter

Courtesy Yokogawa Corp.

Flow measurement is a ubiquitous function in the industrial process control field. Anywhere there are pipes, somebody wants to know what, and how much, is passing through them. Fortunately for us engineers, there is a wide array of industrial flow meters capable of measuring some physical characteristic of fluid moving within a pipe that can be translated into a useful measurement of flow rate.

In industry, there are a number of different technologies used to measure a physical property related to fluid motion, referred to as magnetic, ultrasonic, vortex, Coriolis, differential pressure, and several others. Each methodology exists in the market because it may perform better or cost less when meeting certain performance requirements. This article is focused on magnetic flow meters and when they may be a good candidate for your project.

Here is a list of some of the positive attributes of magnetic flow meters.

• Magnetic flow meters have no moving parts, always a plus.
• General construction arrangement allows for use of an interior liner for corrosion resistance.
• With no sensor insertions into the fluid flow, the impact of the instrument on the flow is minimized.
• Accuracy, when compared to other technologies, is high.
• Application to laminar, turbulent, and transitional flow profiles is permissible.
• General insensitivity to fluid viscosity, specific gravity, temperature and pressure.
• Magnetic flow meter technology can be applied to a very wide range of pipe sizes.
• Device responds rapidly to changes in fluid flow.
• Can be successfully applied to liquids containing heavy particulates.
• Generally long service life with little maintenance.

There are, though, some points about magnetic flow meters which may make them unsuitable for your application.

• Magnetic flow meters only work on liquids with conductivity above a certain threshold. They may be unsuitable for use with hydrocarbons and high purity water for this reason.
• Cannot be used to measure gas flow.
• Pipe must be grounded.
• Typically, the pipe cross section must be filled by the fluid being measured.

This listing of positives and negatives is intended to be very general in nature. Some manufacturers may have product application solutions that overcome some of the negatives, while others may not be able to deliver all of the positives.

Your best course of action:

Use this general overview to start shaping you understanding of where magnetic flow meters may be a good option, and contact a product application specialist to discuss what you want to accomplish. Combining your process knowledge with their product knowledge should move you toward a good solution.