KROHNE BM 26 A EN - Manual (Page 15)

Installation and Operating Instructions BM 26 A 15
1.6 True level indication
1.6.1 Level measurement using the local indicator and scale
The float is equipped with a ring system of permanent magnets for transmission of liquid level to the
indicator. The indicator is linked magnetically to the magnet system in the float.
For design reasons, the minimum level in the measuring tube is given by the lower lateral flange
connection axis i.e. liquid level zero is the centreline of the lower connecting flange. As can be seen
in the diagram of the float and indicator in section 1.2, the bar follows the float below the liquid level.
There is a difference between true liquid level and the indicator position because:
• the float is immersed to a certain depth depending on the product density and float type,
• the float magnets are positioned below the float centreline in order for the float to have good
stability.
The scale is delivered correctly set up for measuring the product specified in the order. The red
reference mark at the top of the measuring tube (item 1 in the diagram below) shows where the top
of the scale must be clamped for the indicator to give an accurate reading of liquid level. No further
adjustment is necessary when the gauge is commissioned.
Note
If there is a large change in product density, a product other than the one specified in the order is
measured or a different float is installed, the scale on the BM 26 A may require adjusting to give an
accurate reading. Contact KROHNE for assistance (see also section 1.6.4 to correct the scale’s
position).
1 Reference mark : the top of the upper red
KROHNE plate must touch the bottom point
of the triangle
2 Scale
3 Measuring tube (containing float)
4 Top clamping collar ( scale-measuring tube)