Siemens SITRANS LG250 Operating Instructions Manual page 66

10 mm (0.394
")
5 mm (0.197
")
2 mm (0.079
")
0
-2 mm (-0.079
")
-5 mm (-0.197
")
0,1 m (3.937
Fig. 33: Deviation SITRANS LG250 in coax version in oil
1 Dead band - no measurement possible in this area
L Probe length
Repeatability
Variables influencing measurement accuracy
Temperature drift - Digital output
Additional deviation through electromag-
netic interference acc. to EN 61326
Influence of the superimposed gas and pressure to the accuracy
The propagation speed of the radar impulses in gas or vapour above the medium is reduced by
high pressure. This effect depends on the superimposed gas or vapour and is especially large at
low temperatures.
The following table shows the resulting deviation for some typical gases and vapours. The specified
values refer to the distance. Positive values mean that the measured distance is too large, negative
values that the measured distance is too small.
Gas phase
Air
Hydrogen
Steam (saturated
steam)
66
1
)
"
0,15 m (5.906 )
"
Temperature
1 bar (14.5 psig)
20 °C/68 °F 0.00 %
200 °C/392 °F -0.01 %
400 °C/752 °F -0.02 %
20 °C/68 °F -0.01 %
200 °C/392 °F -0.02 %
400 °C/752 °F -0.02 %
100 °C/212 °F 0.26 %
180 °C/356 °F 0.17 %
264 °C/507 °F 0.12 %
366 °C/691 °F 0.07 %
SITRANS LG250 - Operating Instructions
L
≤ ±1 mm
±3 mm/10 K relating to the max. measuring range or
max. 10 mm (0.394 in)
< ±10 mm (< ±0.394 in)
10 bar (145 psig)
0.22 %
0.13 %
0.08 %
0.10 %
0.05 %
0.03 %
-
2.1 %
1.44 %
1.01 %
1
0,05 m
0,1 m
(1.97
")
(3.937
")
Pressure
50 bar (725 psig)
1.2 %
0.74 %
0.52 %
0.61 %
0.37 %
0.25 %
-
-
9.2 %
5.7 %
PBD-51041056