KROHNE BM 70 M - Manual (Page 2)

2 BM 70 M
Part 1: Installation and operating instructions for BM 70 M
1 Range of applications..................................................................................................................................................... 5
2 Mode of operation and system structure...................................................................................................................... 5
2.1 Operating principle (FMCW-Radar) .................................................................................................................................. 5
2.2 Signal processing (digital) ................................................................................................................................................. 6
2.3 Modularity (signal converter, flange, antenna) .................................................................................................................. 7
3 Input ................................................................................................................................................................................. 7
3.1 Measured variable (distance, level, volume, reflection) .................................................................................................... 7
3.2 Measuring range ............................................................................................................................................................... 7
3.3 Block distance ................................................................................................................................................................... 8
3.4 Out-of-range performance................................................................................................................................................. 8
4 Output .............................................................................................................................................................................. 8
4.1 Variants ............................................................................................................................................................................. 8
4.2 Ex-e current output HART ® ............................................................................................................................................... 9
4.3 Ex-i current output HART ® (type of protection: Ex de [ia]) .............................................................................................. 10
4.4 HART ® communication ................................................................................................................................................... 10
4.5 Current output (non-communicable) ............................................................................................................................... 11
4.6 Digital interface RS 485 .................................................................................................................................................. 11
4.7 Breakdown signal............................................................................................................................................................ 12
4.8 Digital input ..................................................................................................................................................................... 13
5 Measuring accuracy...................................................................................................................................................... 13
5.1 Reference conditions ...................................................................................................................................................... 13
5.2 Error of measurement ..................................................................................................................................................... 13
5.3 Repeatability ................................................................................................................................................................... 14
5.4 Measured value resolution/hysteresis............................................................................................................................. 14
5.5 Transient recovery time................................................................................................................................................... 14
5.6 Long-term drift................................................................................................................................................................. 14
5.7 Effect of ambient temperature......................................................................................................................................... 14
6 Operating conditions .................................................................................................................................................... 14
6.1 Installation conditions...................................................................................................................................................... 15
6.1.1 Transmission angle ......................................................................................................................................................... 15
6.1.2 Recommendations for positioning on the tank ................................................................................................................ 15
6.1.3 Mounting on tank fitting ................................................................................................................................................... 17
6.1.4 Mounting on stilling wells/ trunks..................................................................................................................................... 18
6.1.5 Wave-Guide .................................................................................................................................................................... 19
6.1.6 Curved antenna extensions ............................................................................................................................................ 20
6.1.7 Special options for the flange.......................................................................................................................................... 20
6.1.8 Ultimate installation on the tank ...................................................................................................................................... 21
6.2
Ambient conditions.......................................................................................................................................................... 21
6.2.1 Hazardous locations........................................................................................................................................................ 21
6.2.2 Ambient temperature of signal converter ........................................................................................................................ 21
6.2.3 Flange temperature......................................................................................................................................................... 21
6.2.4 Ambient temperature limits ............................................................................................................................................. 22
6.2.5 Storage temperature ....................................................................................................................................................... 22
6.2.6 Environment class........................................................................................................................................................... 22
6.2.7 Protection category ......................................................................................................................................................... 22
6.2.8 Shock resistance............................................................................................................................................................. 22
6.2.9 Vibration endurance limit................................................................................................................................................. 22
6.2.10 EMC ................................................................................................................................................................................ 22
6.3
Product conditions........................................................................................................................................................... 22
6.3.1 Physical properties of the products ................................................................................................................................. 22
6.3.2 Relative permittivity (
ε
r
≥ 1.5) .......................................................................................................................................... 23
6.3.3 Product limitations........................................................................................................................................................... 23
6.3.4 Product temperature (unrestricted) ................................................................................................................................. 23
6.3.5 Maximum allowable operating pressure.......................................................................................................................... 23
6.4
Maintenance.................................................................................................................................................................... 24