KROHNE BM 70 M - Manual (Page 44)

44 BM 70 M
8.6.3 Block distance, antenna type and antenna extension
Fct. 3.1.2 BLOCKDIST
• Caked deposits or contamination of the antenna, for example, can cause faulty measurements
directly below the antenna. The function "block distance" is used to specify a zone below the
flange in which measurements are not to be carried out.
• Signals within the block distance are suppressed; a rise in the level above this limit will result
in a measurement corresponding to a distance = block distance, when Fct. 3.5.6 BD-DETECT
= ON.
• Unit and setting range: same as Fct. 3.1.1 TANKHEIGHT.
•
Recommended minimum value (see also Sect. 3.3):
- for stilling wells
- antenna length + 300 mm
- all other versions in storage tanks:
- antenna extension + antenna length + 100 mm
- all other versions in process tanks:
- antenna extension + antenna length + 200 mm
Fct. 3.1.3 ANTENNA
•
The antenna type is factory-set here.
• STANDARD
• BM 70 M: only STANDARD setting possible.
Fct. 3.1.4 ANT.EXTENS.
The length of the supplied antenna extension is factory-set here.
• Unit and setting range: same as Fct. 3.1.1 TANKHEIGHT.
This setting may only be changed when a longer or shorter antenna extension is installed.
Otherwise faulty measurements may result because the BM 70 M allows for this length when
measuring. After changing any antenna extension, record a new empty spectrum, see Sect.
8.6.12. When a curved antenna extension is used, only the vertical component (vertical offset)
should be entered here.
Example (S-shaped extension): Fct. 3.1.4 = 323 mm.
8.6.4 Distance piece
Fct. 3.1.5 DIST.PIECE
The length of any supplied distance piece above the mounting flange is factory-set here.
• Setting range: 0 ... 2000 mm
• Default value: 0 mm
The value of 120 mm should be entered for the high-temperature version of the flange system.
When a curved antenna extension is used, the horizontal component of this extension should
additionally be entered (= geometric length of the pipe minus the vertical offset).
Example (see drawing above): Fct. 3.1.5 = 300 mm.
323 mm
300 mm
(Fct. 3.1.4)
(Fct. 3.1.5)