KROHNE BM 70 A_P EN - Manual (Page 44)

Installation and operating instructions BM 70 A/P Page: 44 11/00
8.6 Description of functions
8.6.1 Choice of units
Level/distance units
Select under Fct. 3.1.1 TANKHEIGHT
•
m • cm • mm
•
inch
•
Ft
The unit selected here is also valid for the following
functions:
- Block distance Fct. 3.1.2
- Antenna extension, Fct. 3.1.4
- Scaling 4 mA value, current output, Fct. 3.3.3
- Scaling 20 mA value, current output, Fct. 3.3.4
- Range for partial tank bottom tracing, Fct. 3.5.2
- Threshold (limit value), switching output, Fct. 3.6.3
- Hysteresis, switching output, Fct. 3.6.4
- Tracking speed, Fct. 3.5.4
(in m/min when Fct.3.1.1 = m, cm or mm
or in ft/min when Fct.3.1.1 = inch or ft)
The Fct. 3.2.2 (length unit for display) can be set
independently of the unit selected under Fct. 3.1.1.
Conversion units
By conversion is meant the transposition of an arbitrary
level value into a "conversion value" (usually volume), so
as, for example, to realize a non-linear function as a factor
of the level.
Options under Fct. 3.2.3 UNIT.CONV.
•
m³ l l ( = litres)
•
US Gal l GB Gal (Gal = gallons)
•
Ft3 l bbl (petroleum barrels)
The unit selected here is also valid for the following
functions:
- Scaling 4 mA value, current output, Fct. 3.3.3
- Scaling 20 mA value, current output, Fct. 3.3.4
- Threshold (limit value), switching output, Fct. 3.6.3
- Hysteresis, switching output, Fct. 3.6.4
•
Display range:
0.00 - 30000.00 m
3
0 - 9999999 Liter
0 - 7925161 US Gal
0 - 6599265 GB Gal
0.0 - 999999.9 Ft3
0.0 - 99999.9 bbl (petroleum barrel)
Note: When the display is set to Liter, ft³ or Barrel, it is
possible that the max. volume will no longer be shown.
In such cases, the special symbol " == " is displayed and
a change possibly made to a different unit. The current
output will in any case output the correct value.
Conversion measurement requires that a conversion table
be set with the PC-CAT program. By means of this table a
conversion value is allocated to each level value (level /
conversion pairs). The values are linearly established
(interpolated) between 2 points.
Also, for the local display an arbitrary (max. 10-character)
text (Fct. 3.2.4) can be defined as a unit under Fct. 3.2.4.
Internally, this "user unit" is treated in the conversion in the
same way as " m³ ".
Examples of application and setting: see Sect. 8.5
Reflection units
The measuring range for "reflection" has a fixed setting of
0...100 (whole numbers). The "reflection" measured value
is a relative measure of the strength of the reflected signal,
converted into an exponential scale: each number step is
approximately equivalent to a change by 0.4 dB; in other
words, about 8 steps signify a doubling of the signal
strength. At full reflection, a value of approx. 90...100 is
measured.
Where measuring distances are greater, the natural
weakening of the signal is automatically allowed for in the
measured value (does not apply to stilling wells, i.e. when
Fct. 3.1.6 = YES).
The measured reflection can be regarded as being a
measure of the reflectivity of a product.