Magnetic Flowmeters

Electromagnetic flow meters or magmeters are used for measurement in water and wastewater industry. Meter installations in large water lines is quite expensive. This is where insertion magnetic flow meters can make a difference. They are inexpensive and assure accurate flow measurements. When an electromagnetic field is formed around a metering tube which may be a part of a water treatment system, it produces a voltage or potential difference in the liquid flowing through it. This voltage is proportional to the flow rate. So, based on the voltage, the volumetric flow rate is measured with the help of a magnetic flowmeter. This simple, handy device measures flow rate based on the principle of electromagnetic induction. At Cannon Water, we provide electromagnetic insertion type flowmeters from brands like Seametrics. All our magnetic flowmeters or mag meters are designed to work in harsh environments and measure the flow rates of fluids with varied consistencies such as liquids, semi-solids, slurries, particulate fluids, and so on.

How Does a Magnetic Flowmeter or Magmeter Work?

These mag meters have a sensor and transmitter which sense and measure the flow rate. The sensor is placed inline within the pipe. The fluid that flows through the pipe produces a voltage, which is measured by the sensor. The transmitter measures the voltage produced by the sensor and converts this value into flow rate and transmits it to the connected control or integrated system. These digital devices have a screen where the values are displayed. They can be installed or mounted horizontally, vertically, or at specific angles. Whatever the mounting type, the electrode axis is always horizontal. The installation process slightly differs with the type of flowmeter.

What is an Electromagnetic Insertion Type Flow Meter?

Electromagnetic insertion type flow meters are designed for highly conductive liquids flowing through 25 to 305 mm pipes. These pipes may be made from different materials such as stainless steel, PVC, brass, and so on. These insertion type flow meters possess no moving parts and can be used in slurry like environments or other dirty environments where debris can be challenging for any regular water flow meter. In short they can be used for measuring flow rates of corrosive conductive liquids such as alkali, salt, and acid. These meters get their name from the type of insertion. They are often installed upstream of the chemical line. Sometimes, they be installed downstream to allow mixing of fluids. These flow meters generally possess current-sinking pulse outputs and are designed for pairing with indicator or transmitter.

How Does an Electromagnetic Insertion Type Flow Meter Work?

These mag meters have a sensor and transmitter which sense and measure the flow rate. The sensor is placed inline within the pipe. The fluid that flows through the pipe produces a voltage, which is measured by the sensor. The transmitter measures the voltage produced by the sensor and converts this value into flow rate and transmits it to the connected control or integrated system. These digital devices have a screen where the values are displayed. They can be installed or mounted horizontally, vertically, or at specific angles. Whatever the mounting type, the electrode axis is always horizontal. The installation process slightly differs with the type of flowmeter.

Working Principle of Insertion Magnetic Flow Meters

All magnetic flow meters are designed to follow the Faraday’s law of electromagnetic induction.

E = CONSTANT x B x D x V

Where E stands for voltage, B for the strength of the magnetic field, D for the path lengths between the probes, and V for the velocity of the medium. The law states that the voltage magnitude of a fluid in a conductive medium is directly proportional to the strength of the magnetic field (B), the velocity of the medium (V) and the path length between the probes (D). All parameters mentioned in this equation, except for velocity can be easily fixed. A mag meter is designed to respond only to the velocity and remains insensitive to other aspects such as viscosity, density, as well as temperature, pressure, fluid pulsation, and mechanical vibrations. 

An insertion type mag meter works typically to an electrical generator. The voltage is induced in the conductor when the fluid moves through the magnetic field at right angles. High voltage is generated if the fluid movement is faster.

Beneficial Features of Magnetic Flowmeters

Flow rate measurement using a flow meter is important in most industrial processes concerning fluid dynamics. This ensures the process runs smoothly and efficiently. These handy digital devices offered by Cannon Water have several beneficial features. Here are some of them:

• As mentioned, using a Magmeter or magnetic flowmeter offers accurate flow rate outputs which are essential to keep the process running efficiently.
• We offer specific models for applications where high accuracy is required. Usually these are inline flowmeters. There are specific mag meters for low flow applications. We also offer insertion flowmeters in applications with large pipes or tubes.
• Most models have no moving parts which reduces the possibility of wear. Hence, they are low on maintenance and do not generally require repairs.
• These flowmeters offer speedy outputs and have a lot of other functionalities such as measuring reverse flow rate, optimizing range setting, and so on.
• The meter only measures the velocity and can remain unchanged for other parameters such as heat, temperature, pressure, electrical conductivity, and so on.
• These meters have infinite measurement ranges. Generally, the low-end limits of the meter are determined by the fluid dynamics in the pipe, as well as the ability of a sensor to measure low signals. Many models of mag meters flow meters available with us have turndown rangeability of 100:1.
• They are used to measure flow rates of liquids with diverse consistencies.

Applications of Insertion Magnetic Flow Meters

Our magnetic flow meters are used for measuring the following fluids:  

• Slurry: Many mineral processing, mining, and wastewater industries produce slurries as their byproducts. Our insertion magnetic flow meters can be used to measure the speed of slurry flow in any process.
• Highly Corrosive Liquids: Many industrial processes involve highly corrosive liquids that are caustic and abrasive in nature. These liquids are commonly found in the chemical feed systems used in water treatment or wastewater treatment facilities and chemical processing plants.
• Dirty Liquids: These liquids are found in water and wastewater treatment, pulp and paper processing industries.

Safety Tips for Operating Insertion Magnetic Flow Meters

The following are safety tips for operating insertion magnetic flow meters:

    1. Avoid operating the flow meter to its maximum conductivity limit.
    2. Choose the flow meter of the proper size as this will help retain the maximum flow velocity at 2-3 meters per second.
    3. Use large magnetic flowmeters in gravity-fed pipes. Such flowmeters help reduce the pressure drop and allow the required amount of liquid to pass through it.
    4. When used for slurry services, ensure to operate the flowmeters above velocity where the solid settles.
    5. Operate the flowmeters at low velocity, which is usually below 3 ft/second, to avoid wear and tear.

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