Siemens SITRANS LG270 Operating Instructions Manual page 75

25 mm
(0.984")
2 mm
(0.079")
0
-2 mm
(-0.079")
-15 mm
(-0.591")
Fig. 35: Deviation SITRANS LG270 in cable version (4 mm/0.157 in), in medium oil
1 Dead zone (no measurement possible in this area)
When using a centering weight, it is only possible to measure up to the upper edge of the cerntering weight.
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 0.13 %
400 °C/752 °F 0.08 %
Hydrogen 20 °C/68 °F
200 °C/392 °F 0.05 %
400 °C/752 °F 0.03 %
PBD-51041506
1
0,15 m 0,2 m
(5.906") (7.874")
10 bar
(145 psig)
0.22 %
0.10 %
SITRANS LG270 - 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)
Pressure
50 bar 100 bar
(725 psig) (1450 psig)
1.2 % 2.4 %
0.74 % 1.5 %
0.52 % 1.1 %
0.61 % 1.2 %
0.37 % 0.76 %
0.25 % 0.53 %
1
0,1 m
(3.937")
0,15 m
(5.906")
200 bar 400 bar
(2900 psig) (5800 psig)
4.9 % 9.5 %
3 % 6 %
2.1 % 4.2 %
2.5 % 4.9 %
1.6 % 3.1 %
1.1 % 2.2 %
75