Magnetic Flow Meter Basics

Magnetic Inductive Flow Meters

A magnetic flow meter, also referred to as mag flow meter or magmeter, is a volumetric flow meter that measures liquids or liquid slurries that have a minimum conductivity of 5 µS/cm.  Magnetic flow meters will typically not work with hydrocarbons, distilled water, non-aqueous solutions and non-conductive solutions.

Magnetic flow meters utilize Faraday’s Law of Electromagnetic Induction to determine the velocity of a liquid flowing in a pipe.  Magnetic flow meters consist of a nonmagnetic flow tube, liner, electrodes and electromagnets to generate a magnetic field. In magnetic flow meters, a magnetic field is generated and channeled into the liquid flowing through the pipe.

Operating according to Faraday’s Law, signal voltage (E) is dependent on the average liquid velocity (V) the magnetic field strength (B) and the length of the conductor (D) which in this instance is the distance between the electrodes.

Faraday’s Formula
E is proportional to V x B x D where: 

E = The voltage generated in a conductor
V = The velocity of the conductor
B = The magnetic field strength
D = The length of the conductor

Mag Meter Operation

The liquid flowing through the pipe is the conductor, and electromagnetic coils surrounding the flow tube generate the magnetic field. The signal is sensed by the two electrodes embedded on opposite sides of the flow tube. The flow signal at the electrodes is directly proportional to the flow velocity, the intensity of the magnetic field, and distance between electrodes.

Magnetic flow meters do not require much upstream and downstream straight runs so they can be installed in relatively short meter runs. 

Advantages of using Electromagnetic Flow Meters

The main advantages of using magmeters is that they feature an obstruction-free design with no moving parts which eliminates flow impediment, requires less maintenance and can be used on very large line sizes.  Accuracy over a wide flow range can be as good as ±0.5%

Mag Meter obstruction free flow path and no moving parts

Mag meters perform extremely well in many municipal and processing applications and is the meter of choice for measuring conductive liquids such as water or slurry. Magmeters also have the advantage of being able to measure both very low flows and very high volume flow rates.

Disadvantages of using Magnetic Flow Meters

Magnetic flowmeters are only effective on conductive fluids, and materials such as unmixed hydrocarbons and gases cannot be measured. However, magnetic materials themselves may also present problems, as hydrodynamic effects can alter the normal flow pattern and disturb the velocity rate enough to interfere with operations. Depending on their size and capacity, magnetic flowmeters can be relatively heavy, and those with higher corrosion and abrasion resistance can be expensive.

Typical Industries Where Magnetic Flow Meters are Used

  • Water/Wastewater Industry
  • Brewing, Distilling, and Wine Making
  • Chemical
  • Food and Beverage
  • Power Generation
  • Pulp and Paper
  • Metals and Mining
  • Pharmaceutical
  • HVAC
  • Mining/Mineral Processing

Magnetic Flow Meter Selection

Key questions which need to be considered before selecting a magnetic flow meter

  • Is the fluid conductive or water based?
  • Is the fluid or slurry abrasive?
  • Minimum and maximum flow rate for the flow meter?
  • Minimum and maximum process pressure?
  • Minimum and maximum process temperature?
  • Is the fluid chemically compatible with the flow meter wetted parts?
  • What is the size of the pipe?
  • Is the pipe always full?
  • Do you require an integral display or remote display?
  • Do you require an analog output?

Magnetic flow meters require a minimum medium conductivity for the technology to measure flow. This chart provides a general guideline on conductivity of common media.

Conductivity of common media for magnetic flow meter applications
Conductivity of Common Media

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Fire-Safe Shut Off Valves for Distillery Application

Problem: A local distillery was directed by their insurance agency to incorporate fire safe shut off valves on their storage tanks to ensure closure of outlet valves to isolate flammable liquids in the event of fire.


Fire Safe Shut off Valves

The head brewer at the distillery contacted us as they had successfully used Assured Automation automated valves and flow meters for previous jobs.

An Assured Automation product specialist suggested the use of the FM Fire-Safe Series. These FM approved thermal shut off valves are spring loaded with a thermal link. When the link burns in fire conditions the spring brings the API607 firesafe ball valve to a closed position, preventing the release of flammable liquids which could potentially feed a fire.

FM Fire Safe Series

Having a fire safety shutoff system in place is very important at any facility which deals with flammable liquids or gasses. The Assured Automation FM Fire-Safe Thermal and Electro-Thermal Emergency Shutdown Valve assemblies are constructed to automatically close or open and mitigate any conditions which could be deemed potentially dangerous.

Both the ball valve and butterfly valve designs are Factory Mutual (FM) approved. Thermal valves have thermal links which operate the valve at a predetermined temperature. The electro-thermal valve adds an electro-thermal link which can be triggered by a low power electrical current impulse, such as a smoke detector alarm. Both valve designs can also be operated manually without affecting the viability of the link.

The FM Fire-Safe valves are the perfect choice when the flow of hazardous liquid or gas needs to be completely halted due to the presence of fire. The valves can also be implemented in fire suppression systems, to release fire retardant in an isolated area instead of the entire plant.

3-piece Ball valve designs are available in sizes from 1/2 to 6”; thermal activation temperatures from 165 to 360° F; threaded, socket weld, butt weld, and flanged connection configurations. Butterfly valves are available in sizes from 2” to 12”; thermal activation temperatures from 165 to 360° F; carbon steel or 316 stainless steel.

FM FireSafe Shut off Valves

FM Fire-Safe Series Thermal Shut-Off Valves
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Assured Automation to Exhibit at 2019 Craft Brewers Conference & BrewExpo America

April 8, 2019 – April 11, 2019
Location: Colorado Convention Center – Denver, CO
Assured Automation Booth: 21090

Craft Brewers Conference

The Craft Brewers Conference (CBC) is the only industry event that serves both brewpubs and packaging breweries. This is an annual show that travels to different cities each year.

The Craft Brewers Conference and BrewExpo America® is presented by the Brewers Association, a recognized leader in the national and international brewing arena.

For professional brewers, CBC is the number one environment in North America for concentrated, affordable brewing education and idea sharing to improve brewery quality and performance. Twelve distinct educational tracks provide attendees with over 80 seminars led by top minds in the beer world.

Bringing together more than 13,000 attendees and 800 Exhibitors, BrewExpo America® allows exhibitors and buyers to develop profitable business relationships and helps brewing professionals encounter the latest and best products and services that industry vendors have to offer.

Stop By Booth 21090

Assured Automation has been providing manual and automated valves, actuators, flow meters and valve accessories to the brewing industry since 1983.

Brewers of all sizes have come to rely on Assured Automation for our quality products, expert service, and the ease of using our interactive online Valve Configurator to quickly specify valve assemblies. 

Stop by Booth 21090 to speak with one of our Valve Specialists and learn how “We Make Valve Automation Easy!

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Assured Automation Becomes an ITAR Compliant Valve Manufacturer

Products,  Procedures and Facility meet the strictest standards for military applications

ITAR Assured Automation

According to the Arms Export Control Act (AECA) and International Traffic in Arms Regulations (ITAR ) Assured Automation has successfully registered with the State Department’s Directorate of Defense Trade Controls (DDTC) . We are now considered an ITAR Compliant Valve Manufacturer.

What is ITAR?

The International Traffic in Arms Regulations (ITAR) is the United States regulation that controls the manufacture, sale, and distribution of defense and space-related articles and services as defined in the United States Munitions List (USML).

Why have we become ITAR Compliant?

Any company in the United States that handles, manufactures, sells, or distributes items on the USML must adhere to Arms Export Control Act (AECA) and be ITAR compliant.

The State Department’s Directorate of Defense Trade Controls (DDTC) manages the list of companies who can deal in USML goods and services, and it is up to each company to establish policies to comply with ITAR regulations.

What steps have we taken to become ITAR Compliant?

Changes have been made to Assured Automation policies and procedures to ensure that the control of products and information relating to military projects is held to the highest standards.

  • Training of all Assured Automation employees in ITAR policy.
  • Implementation of a strict new Visitor Policy restricting access to ITAR testing area
  • Construction of an ITAR restricted area designated strictly for testing and documentation of military projects

A Commitment to Quality

In addition to being ITAR Compliant, Assured Automation is also ISO Certified.

Assured Automation has been ISO 9001:2008 certified since 2010 and achieved the upgraded 9001:2015 standard in 2017.

These standardizations focus on putting customers first. Our goal is to consistently meet customer needs to enhance their satisfaction through thoughtfully defined objectives that force us to work more efficiently while identifying areas that need improvement.

That’s how We Make Valve Automation Easy for our customers!


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2 Ball Valves Mounted on One Actuator

Project Showcase: Specialized equipment manufacturer requires 2 brass ball valves mounted on one pneumatic actuator for infrared boiler thermometer application

2 Ball Valves One Actuator

Specialized equipment manufacturer requires 2 ball valves on one actuator

Customer Type Specialized Equipment Manufacturer
Application Infrared Boiler Thermometer
Valve Series 101 Series Nickel Plated Brass 2 -Way Ball Valve
Actuator Series O Series Double Acting Pneumatic Actuator
Valve Size  3/8″, 1 1/2″
# of Valves 50
Sales Person Mike O
Valve Assembly Technician Mike T


A manufacturer of specialized performance and maintenance equipment required a 1½“ and a 3/8” ball valve be mounted on a double acting pneumatic actuator as part of an infrared thermometer assembly for in-situ mounting on furnaces for sensing internal gas temperatures.


Assured Automation product specialist, Mike O’Neill, supplied 101 Series 2 way brass ball valves and O Series spring return pneumatic actuators.


101 Series Ball Valves

The 101 Series is a full port, brass, NPT threaded end actuated ball valve. It can be equipped with a manual handle or with direct mount pneumatic or electric actuators. The direct mount actuators eliminate the valve-actuator mounting kit, which adds unnecessary height and expense. Available in ¼” to 3”



O Series spring return pneumatic actuators offer a simple and cost-effective solution for your valve automation needs.  For use on quarter turn (90 degree) ball valves, plug valves, dampers, and resilient seated butterfly valves.

Spring return pneumatic actuators use compressed air to move the piston in one direction, and a spring to push it back in the other when the air is stopped and allowed to vent.

The most important aspect of a spring return actuator is that it offers a “fail-safe” position which means that if the air supply is lost, or electric power to the solenoid that controls the air is lost, the valve will travel to this position using the force of the spring(s). This could be either open or closed, whichever offers a safer outcome.

These dual scotch yoke style actuators have higher torque values at the start and end of the stroke.

Long time team member, Mike Thompson was the assembly lead on this project which consisted of over 25 automated valve assemblies.

Contact us today to see how “We Make Valve Automation Easy!”



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Globe vs. V Port Ball Valves for Flow Control Applications

In most process applications there are two different types of valves used: on/off and control. On/off valves allow full flow or stopping flow completely. Control valves, in contrast have the ability to control the AMOUNT of flow, also known as throttling.

V-Port Ball Valves

V-Ball Control Valve

V Series V-Port Ball Valve

V-Port ball valves are a specialized ball valve that offer:

  • Suitability for coarse control applications
  • Reliable shutoff
  • Many different V-Port balls options available to accommodate different flow ranges with the same valve body, most common being 60˚, 30˚, and 15˚

Globe Valves 

GVI Series Globe Valve

Globe valves use linear actuation and offer:

  • More precise control due to a more linear flow curve (See Figure 3 below)
  • Do not suffer uneven wear in the mid positions
  • Typically have higher pressure drops than V-Port valves

However, they do not typically provide a bubble tight shutoff. They also require greater force or a larger actuator to seat the valve.


V Port Ball Valve and Globe Valve Comparison


V Port Valve Globe Valve
Function 2-way flow control 2-way flow control,
3-way mixing,
3-way diverting
Positive Shutoff YES Not leak free
Control Capability Coarse Fine
High Duty Cycle NO YES (constant)
Flow Capacity Higher Lower
Cavitation Prevention
High Temperature Preferred
Ease of Maintenance Preferred
Cost More economical

V-Port Ball Valve (rotary) vs. Globe Valve (linear) Flow Curve

Download full article as seen in Valve World Americas

V-Port Ball Valve (rotary) vs. Globe Valve (linear)

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Sanitary Ball Valves for Fragrance Encapsulation Skid

Project Showcase: Fragrance Manufacturer requires sanitary ball valves and flanged ball valves for fragrance production application

sanitary ball vavles

Leading fragrance manufacturer required sanitary ball valves and flanged ball valves

Customer Type Fragrance Manufacturer
Application Fragrance Oil-liquid process and steam for heating reactor jackets
Valve Series 30D , BFY, 36 , F150 Series
Actuator Series F Series Rack & Pinion Pneumatic Valve Actuator
Valve Size 1/2″-4″
# of Valves 25
Sales Person Mike O.
Valve Assembly Technician Antwuan T.

APPLICATION:  A leading fragrance manufacturer required a variety of valves for a fragrance encapsulation process skid.  Sanitary ball valves with tri-clamp ends were required for the fragrance lines. Flanged valves with 50/50 seats were required on the steam line.

Mike O’Neill

Assured Automation product specialist, Mike O’Neill, supplied 30D sanitary 3-way ball valves, BFY Series sanitary butterfly valves, 36 Series stainless steel ball valves for the process lines and 150F Series flanged ball valves for the steam line.

The 30D 3-way ball valve is a full bore tri-clamp sanitary ball valve with cavity filled teflon seats. This valve is ideal for use in flavor and fragrance and other clean service applications meeting  FDA and USDA 3A requirements.

30D Series

Valve body is constructed of ASTM 316 stainless steel with sanitary tri-clamp end connections. Sizes available in ½” through 4”.

30D Series has been used successfully in flavor and fragrance, brewing, dairy, water bottling, food and beverage, biotech, and pharmaceutical applications.


Related articleDiverter Ball Valve for Flavor and Fragrance Application



sanitary butterfly valve

BFY Series

BFY series sanitary butterfly valves are full port butterfly valves with tri-clamp or butt weld connections. 316L mirror finish disc provides an even flow preventing obstructions and restrictions.

Opposing body bolt design prevents loosening between body sections due to vibration and operation and provides positive sealing.

Surface finish meets 3-A, FDA & USDA standards. Available in 1/2″-6″.



36 Series

The 36 Series ball valve is constructed of 316 stainless steel. The superior stem seal design of this 3-piece ball valve provides increased cycle life making it the perfect choice for automat

ed valve package designs.

The teflon stem packing is live loaded with Belleville washers to provide constant tension on the stem seals. This ensures a bubble tight stem seal and increases the life cycle of the seal even in high cycle applications. Sizes available in 1/4” through 4”.


Flanged ball valves

150F Series

150F Series ANSI flanged ball valves are API 607-5 firesafe designed, ideal for use on steam for heating reactor jackets and other chemical process applications.

This series features a floating ball and protected seat design. Available in stainless steel or carbon steel, ½”-8”.

Antwuan Thompson


Antwuan Thompson was the assembly lead on this project which consisted of over 25 automated valve assemblies ranging from 1/2″ to 4″.

Contact us today to see how “We Make Valve Automation Easy!”




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Pneumatic Actuated Butterfly Valve for Water Treatment Application

Project Showcase : ST Series resilient seat pneumatic actuated butterfly valve ideally suited for water treatment applications.

Application:  A leading equipment manufacturer required resilient seat pneumatic actuated butterfly valve for a horizontal pressure filter system.

Pneumatic actuated butterfly valve

Customer Type Manufacturer of  Water Treatment Equipment
Application Horizontal Pressure Filters
Valve Series ST Series Lug Style Resilient Seated Butterfly Valve
Actuator Series F Series Rack & Pinion Pneumatic Valve Actuator
Valve Size 6″-12″
# of Valves 35
Sales Person Vinnie C.
Valve Assembly Technician Dan R.

A leading manufacturer of water and wastewater treatment equipment required a butterfly valve for a pre-treatment pressure filter fabrication.

Pressure Filters are used to remove suspended particle, color and odor from water. Typical applications include: Clarifier Effluent Polishing, Cooling Tower Sidestream Filtration, Reverse Osmosis Pretreatment, Iron & Manganese Removal, Direct Filtration With or Without In-Line Coagulation.

Assured Automation product specialist, Vinnie Collier, recommended the  STL Series butterfly valve, F Series actuator, C Series solenoid and YO Series proximity limit switch for this pressure filter application.

Valve Series:  STL Series resilient seat 125/150 ductile iron lug style butterfly valve.

ST Series quarter turn resilient seated butterfly valves are ideal for demanding service applications. These reliable, low maintenance shut-off and control valves are available in 2”-24”.

ST Series butterfly valves are designed for use in gas and liquid applications, to a maximum working pressure of 225psi. They are equipped to handle an operating temperature range of -22 degrees F to + 230 degrees F. ST Series offers an economical alternative to plug, gate, and ball valves.

Typical ST Series applications include:

  • Water and waste effluent treatment plants
  • Paper, textiles and sugar industry
  • Construction industry, and drilling production
  • Heating, air conditioning, and cooling water circulation
  • Pneumatic conveyors, and vacuum applications
  • Compressed air, gas and desulphurization plants
  • Brewing, distilling, and chemical process industry

complete pneumatic actuated butterfly valve assembly

Actuator Series: F Series pneumatic valve actuator has less space requirements due to its compact design

The F Series compact double acting rack and pinion actuator has even torque output through the entire 90° rotation of the stroke offering a simple and cost effective automation solution.

Solenoid Series: C Series NAMUR solenoid valve features a high Cv to cycle the actuators quickly and features a manual override button to test the actuators.

Limit Switch Series: YO Series explosion proof limit switch features bright LED lights that coincide with the open/close indicator.

Dan Roszkowski was the assembly lead on this project which consisted of over 35 butterfly valve assemblies ranging from 6″ to 12″.

Dan’s attention to detail was noted by the engineer inspecting the job for the water treatment equipment manufacturer.

The job was released for immediate shipment.

Configure a ST Series Assembly Today!

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Coaxial Valves vs. Ball Valves for On/Off Applications

For basic on/off service in process, water, or virtually any application, a ball valve is a common choice. There is, however, another option that should be considered. Coaxial valves are an excellent choice for on/off applications also, and have MAJOR advantages. Read below to learn why a VA Series coaxial valve might be the best choice for your application.

VA Series Coaxial Valve Advantages

  • Smaller
  • Lighter
  • Faster
  • Less Expensive
  • Higher Cycle-life
  • Safer (no moving parts)

Coaxial Valves vs. Ball Valves for On/Off

This is an actual size comparison of 1″ NPT ON/Off valves with dual (open & closed) proximity sensor limit switches.

Details of these Advantages


The VA series coaxial valve with integral actuator is only slightly larger than JUST THE VALVE in the ball valve assembly. The limit switches are tiny, and attach to a simple bar that clamps on to the valve body using simple set screws. If a solenoid valve is to be used (not shown above) it is a NAMUR mounting interface to maintain the compact streamlined assembly.


While the VA valve may be slightly larger than the ball valve equivalent. The fact that it includes the actuator eliminates the additional weight of the rotary actuator needed on a ball valve assembly. This makes it much lighter than an air actuated ball valve of equal size.


The volume of air required to actuate the VA series is much less than that needed vs. a ball valve of the same size. The shuttle inside the valve has a relatively short travel distance.

Less Expensive

The VA series air-operated coaxial valve costs far less than an air-operated ball valve. The savings can be as much as 50% or more. You don’t have the added expense of an actuator, or that of the time and hardware needed to install it.

The cost of operation is also less due to the lower volume of air consumed.

Higher Cycle-Life

The higher cycle-life also provides more value. It extends the life of the valve and requires less frequent seal replacement. VA valves have reached 5 million cycles! This saves on replacement seals, maintenance costs, and reduces system down time.


There are no external moving parts on the VA coaxial valves. Certain limit switches do move externally on the rotary actuators used in ball valve assemblies.

VA Coaxial Valve vs. Ball Valve Comparison (1″ NPT valves)

VA Coaxial Valve 3-piece Ball Valve w/
pneumatic actuator
Dimensions 5.6″ x 3″ x 2.7″ 7.55″ x 3.76″ x 8.5″
Weight 4.15 lbs. 8 lbs.
Cycle Speed .02 (air stroke)
.04 (spring stroke)
.05 (spring stroke)
.06 (air stroke)
Cv 17 116
Cost (no limit switch) $175 (DA)
$184 (SR)
$376 (DA)
$473 (SR)
Cost (dual prox. limit switch) $355 (DA)
$364 (SR)
$586 (DA)
$683 (SR)


Lower Cv

As you can see in the chart above, there is one disadvantage when using VA series valves. The Cv is much lower. This makes a full-port ball valve a better choice for applications with high flow rates, or where minimal pressure drop is a critical factor.

Fluid Compatibility

The VA series has a limited selection of seal materials which includes Buna, EPDM, and Viton®. This limits the media that can be controlled to those that are compatible with any of the 3 choices.


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When You Need a Diverter Valve for Ink, Paint Dispensing, and Caustic Media

Diverter valves are one type of 3-way valves. Unlike modulating and mixing 3-way valves that combine two inputs into one output, diverter valves separate one input into two outputs. Diverter valves are frequently used in control processes because they are less expensive and require less space than using multiple 2-way valves to divert flow. Although multiple 2-way valves can achieve the same goal of diverting, or mixing, the additional cost of purchase, installation, and maintenance on two 2-way valves, and the larger footprint required, more than justifies the use of a single 3-way valve. Factoring in the cost of actuation, a single actuated 3-way valve can save thousands of dollars over multiple 2-way valve configurations.

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