From Flow Measurement
Magnetic flowmeters (magmeters) are designed to measure the flow of electrically
conductive liquids in a closed pipe. They are volumetric flow-measuring
devices and have been commercially available since the mid-1950s. Sizes range
from 1/25 inch to about 120 inches from most manufacturers. This covers a flow
range of about 0.003 gallon per minute to about 1,100,000 gallons per minute.
Early units were flanged devices that bolted to adjacent pipe flanges in much the
same way as an ordinary section of flanged pipe. They were large, heavy, and
expensive, but they offered several advantages over other flowmeters available at
that time.

Advantages:

  • Obstructionless design
  • Linear output
  • Corrosion-resistant
    wetted parts
  • High accuracy

With the obstructionless design, there are no moving parts to wear and no pressure
drop other than that offered by a section of pipe with equal length and inside
diameter. The only wetted parts are the electrodes and an insulating liner. These
can be selected for compatibility with the most corrosive of chemicals as well as
to meet sanitary requirements for food applications such as milk and other liquid
dairy products. The output signal is linear and directly proportional to the flow
velocity. Accuracy over a wide range (typically 30...


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© 2001 ISA

Products & Services
Flow Controllers
Flow controllers monitor and maintain flow-rate variables, typically in process applications.
Gas Flow Meters
Gas flow meters are used for measuring the flow or quantity of a moving gas in an enclosed pipe or passage.
Liquid Flow Meters
Liquid flow meters are used to measure the volumetric flow rate or amount of a moving liquid.
Volumetric Gas Flow Switches
Volumetric gas flow switches are devices with a switch output used for measuring the flow or quantity of a moving gas in terms of a unit of volume per unit time, such as cubic feet per minute.
Volumetric Liquid Flow Switches
Volumetric liquid flow switches measure the flow or quantity of a moving fluid in terms of a unit of volume per time, such as liters per minute. These flow sensing devices have a switch output.

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