Siemens SITRANS LG250 Operating Instructions Manual page 75

15 mm
(0.591 )
"
2 mm
(0.079
")
0
-2 mm
(-0.079 ")
1
-15 mm
(-0.591 )
"
0,2 m
(7.874
Fig. 35: Deviation SITRANS LG250 in cable version (ø 4 mm/0.157 in, PFA-coated), in oil
1 Dead zone (no measurement possible in this area)
L Probe length
Non-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 on measurement 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 vapours.
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 Temperature
Air 20 °C (68 °F)
200 °C (392 °F)
400 °C (752 °F)
Hydrogen 20 °C (68 °F)
200 °C (392 °F)
400 °C (752 °F)
PBD-51041053
0,35 m
) (13.78
" ")
≤ ±1 mm
±3 mm/10 K relating to the max. measuring range or
max. 10 mm (0.394 in)
< ±10 mm (< ±0.394 in)
1 bar (14.5 psig)
0 %
-0.01 %
-0.02 %
-0.01 %
-0.02 %
-0.02 %
SITRANS LG250 - Operating Instructions
L
(1.969
Pressure
10 bar (145 psig)
0.22 %
0.13 %
0.08 %
0.1 %
0.05 %
0.03 %
1
0,05 m
")
0,2 m
(7.874
")
50 bar (725 psig)
1.2 %
0.74 %
0.52 %
0.61 %
0.37 %
0.25 %
75