KROHNE BM 26 A EN - Manual (Page 48)

48 Installation and Operating Instructions BM 26 A
8 Measuring principle
The instrument operates on the principle of communicating tubes. The measuring tube is connected
as adjacent to the tank (i.e. a bypass chamber) such that the same conditions are obtained in the
tube as those in the tank.
The float is equipped with a number of permanent magnets to transmit measured values to the local
indicator. Two methods of local indication are used:
Standard bar indicator
The indicator tube contains a magnetised indicator bar that follows changes in floater position.
1 Indicator tube
2 Bar (float-following indicator)
3 Measuring scale
4 Magnets set inside the float
5 Measuring tube
Optional flap indicator
The magnet mounted in the float activates (rotates) the magnetic flaps according to the liquid level in
the indicating section of the indicator. The column of reversed yellow magnetic flaps, or the vertical
position of the follower magnet, is the indication of the liquid level. Additionally, the liquid level can
be read off from a large-size scale in various units of length or graduations showing percentages or
volumes.
1 Black front face of flap indicator
2 Flap rotates as magnet in float
moves past this point
3 Yellow reverse face of flap
indicator
4 Flap indicator tube
5 Magnets set inside the float
6 Measuring tube
7 Measuring scale
Remote indication is possible by choosing the level transducer and level switch options. Information
on their working principles and characteristics are given in sections 2 and 3 respectively.