KROHNE BM 70 M - Manual (Page 8)

8 BM 70 M
3.3 Block distance
The block distance is the minimum measured distance between the mounting flange (reference
point) and surface of the tank product.
Recommended minimum values:
Horn antenna without stilling well Stilling well / Wave-Guide
The length of any antenna extension used must be
added on!
3.4 Out-of-range performance
When the level measuring range is exceeded (including flooding) the measured value will stick at
the (adjustable) block distance (see Sect. 8.6.14).
If the measured value drops below the level range, it will stay put at the set lower range limit
(distance = tank height).
4 Output
4.1 Variants
Variants Remarks Described
in Section
Ex-e current output
HART
®
Ex-e; active; HART
®
protocol;
together with switching output and digital input
4.2 + 4.4
Ex-i current output HART ® intrinsically safe; passive; HART ® protocol
(optionally with intrinsically safe switching output)
4.3 + 4.4
Current output Ex-e; active; non-communicable 4.5
RS 485 + current output BM70 protocol or ModBus-RTU or HART ® 4.6 + 4.5
PROFIBUS-PA intrinsically safe; see Supplementary Instructions -
Foundation Fieldbus (FF) intrinsically safe; see Supplementary Instructions -
All versions with HART ® or BM70 protocols can be operated with the PC-CAT PC program (see
Section 8.12).
Product surface Storage tanks: 10cm/4"; Process tanks: 20cm/8"
Antenna size* = Type3: 22cm/8.7"; Type4: 34cm/13";
* Hastelloy: +3cm / 1,2 "
Recommended antenna distance:
Product
Antenna size * = Type1: 11cm/4";
Type2: 15cm/5.5"; Type3: 22cm/8.7"
Recommended antenna distance =
30 cm / 12"
(Wave-Guide: no antenna)
* Hastelloy: 3 cm (0.4")
Wave-Stick SW: 6cm/2.4"
Maximum
level
Block
distance