In the insertion-type magnetic flowmeters, how is the signal measured?

 

The signal is measured in exactly the same way as in a conventional magmeter...there is a very low voltage and very low amperage signal induced
on the electrodes by the passage of the conductive fluid through the sensor field.

The difference between a conventional magmeter and every insertion magmeter but one is that a conventional magmeter's field extends from pipewall to pipewall in all directions, and _all_ of the velocity vectors of the moving fluid are components of the signal. In an insertion magmeter, the field is roughly a sphere of 1 cm diameter, located at the tip of the probe.

For all intents and purposes, an insertion magnetic flowmeter has the same inherent accuracy as a paddlewheel flowmeter.

This specifically does not include the Marsh-McBirney MultiMag, which has multiple magnetic sensors and operates very much analogously to a multiple port pitot tube, with magnetic sensors replacing the multiple ports.

Walt Boyes
co-author, _The Consumer Guide to Magnetic Flowmeters_ available from
isa.org and amazon.com

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Klaus from Germany:

Is the author in the position to provide installation details for the flowmeter in question: what are the minimum distances behind valves, bends and the like, the flowmeter can be installed without being negatively influenced by turbulances?

Regards

Klaus