Click here to enlarge imageThis book series is unique in providing this comparison data. Some buying patterns and marketing strategies may be altered as an outcome of the research. The report will be updated on a continuing basis because of dynamic changes in the flowmeter marketplace due to acquisitions, product additions and deletions.
Magnetic Flowmeter Categories
Ceramic-lined. Ceramic magnetic flowmeters have abrasion-resistant liners typically made of alumina ceramic instead of the typical elastomer linings usually found in magnetic flowmeters. They often permit higher temperature operation, and because their electrodes are typically part of the ceramic substrate, they tend not to offer a leak path between the electrode and liner.
Electrodeless. So-called "electrodeless" magnetic flowmeters employ electrodes that are not in direct contact with the fluid. These electrodes are either embedded in the liner or located behind the liner, and are usually capacitatively-coupled to the flowing liquid.
Low flow. Low flow magnetic flowmeters include sizes below 12 mm (0.5 inch) in diameter. Many have ceramic linings with embedded electrodes.
Medium flow. Medium flow magnetic flowmeters include flanged and wafer-style meters that are between 0.5 inch (12 mm) and 300-450 mm (12-18 inch) in diameter. A large number of magnetic flowmeter models fit into this category.
High flow. High flow (over 300-450 mm/12-18 inch) magnetic flowmeters are larger in size, ranging to over 2 meters in diameter.
High-noise. Many liquids, including slurries, produce signals that contain large amounts of noise. These magnetic flowmeters are designed to produce usable flow measurements even in high-noise environments.
Low-conductivity. Traditionally, magnetic flowmeters could not be used for liquids having an electrical conductivity of less than about 5-20 uS. Several designs permit measurement of fluids with conductivities far less than the traditional level.
Partially-full. Many conduits, especially in wastewater and storm water runoff applications, are only full part of the time. Partially-full magnetic flowmeters are designed to measure flow using both liquid velocity and liquid level to determine flow rate when the conduit is completely not full of liquid.
Fast response. While many applications find the response time of traditional magnetic flowmeters suitable to the service, other applications require measurement where flow changes rapidly, or where the duration of the flow may be on the order of only a few seconds. Fast response magnetic flowmeters are designed to quickly respond during these short time periods.
Sanitary. Sanitary magnetic flowmeters are designed and fabricated with materials and finishes that allow application in the food and pharmaceuticals industries where they may be cleaned in place (CIP) or steamed in place (SIP) to reduce or remove bacterial contamination.
Two-wire. Traditionally, to generate a sufficient magnetic field, magnetic flowmeters required separate wiring to a source of power in addition to analog signal wiring. Two-wire, or loop-powered magnetic flowmeters are designed to operate on the power available from the loop power supply. Most two-wire designs run on available 4-20 mADC loop power, but some designs require higher power levels to operate over two wires.
Books in the series:
The Consumer Guide to Coriolis Mass Flowmeters
The Consumer Guide to Differential Pressure Flow Transmitters
The Consumer Guide to Magnetic Flowmeters
The Consumer Guide to Ultrasonic Flowmeters (available early 2004)
The Consumer Guide to Vortex Shedding and Fluidic Flowmeters
All of these books are available at the ISA Bookstore (www.isa.org).
Author's Note
David W. Spitzer has more than 25 years of experience in specifying, building, installing, start-up and troubleshooting process control instrumentation. Mr. Spitzer is a member of ISA, and belongs to ASME MFC and ISO TC30 committees. He has published a number of books concerning the application and use of fluid handling technology, including "The Consumer Guide to..." series. Mr. Spitzer is currently a principal in Spitzer and Boyes, LLC, based in Chestnut Ridge, New York.