Parameter assignment
7.20 Range calibration (P652 to P655)
SITRANS Probe LR with mA/HART
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Operating Instructions, 05/2019, A5E32337711-AC
7.20.1
P652 Offset correction
A fixed offset value that is added to the reading as a correction to the measurement.
Values
Range
–99999 to 99999
Default
0.000
7.20.2
P655 Propagation factor
The value used to compensate for changes in microwave velocity due to propagation within
a metal stillpipe, instead of in free space.
Values
Range
0.3000 to 1.5000
Default
1.000
Pipe size (I.D.)
Propagation Factor
1)
50 mm (2”)
0.827
80 mm (3”)
0.915
100 mm (4”)
0.955
150 mm (6”)
0.980
200 mm (8”)
0.990
1)
Contact your Siemens representative for other sizes and propagation factor numbers.
The propagation factor is constant for a given pipe diameter, or can be determined by
comparing the radar distance reading to the actual process material distance (measured
from the reference point). For the reference point, see SITRANS Probe LR dimensions
(Page 84).
Example:
①
SITRANS Probe LR distance
Actual distance / SITRANS probe LR distance= p.f. (propagation factor)
Using the readings shown:
10.42 m / 12.6 m = 0.827
Enter the propagation factor: 0.827