NBK-M
4.4. Magnetostrictive Level Transmitter (option..T..)
Remote level transmission can be achieved by mounting a magnetostrictive sen-
sor outside the bypass tube. A continuous standard 4 to 20 mA signal is obtained
with a built-in transmitter. This signal can then be displayed on analog or digital
indicators, or taken as an input to a computer system.
5. Operating Principle
The NBK-M is a bypass tube which is attached to the top and bottom of a vessel.
The liquid level in the bypass tube will equalize with the liquid level in the vessel
and will therefore will correspond to the level in the vessel to which it is attached.
A float with flush-encased magnet in the bypass tube follows the liquid level. The
magnetic float activates a roller indicator that is externally attached. As the float
passes by, the red/white rollers rotate through 180° about their own axis. Red
indicates the actual level, whereas white means no level. The actual tank level is
read at the red/white roller interface.
The float’s magnetic field propagates in an annular fashion 360° around the
periphery of the float. For this reason, the roller indicator, switches and level
transducer can be mounted anywhere on the external portion of the bypass tube
within the limits of float travel.
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