57
10 Supplement
VEGAPULS 66 • 4 … 20 mA/HART - two-wire
28438-EN-170927
Deviation
12)
see diagrams
1,0 m (3.28 ft)
35 m (114.8 ft)
20 mm (0.788 in)
10 mm (0.394 in)
- 10 mm (- 0.394 in)
- 20 mm (- 0.788 in)
0
Fig. 36: Deviation VEGAPULS 66
Influence of the ambient temperature to the sensor electronics
13)
Average temperature coefficient of the
zero signal (temperature error)
0.03 %/10 K
Influence of the superimposed gas and pressure on measurement accuracy
The spreading speed of the radar impulses in gas or vapour above the product is reduced by high
pressures. This effect depends on the superimposed gas or vapour and increases with low tem-
peratures. The following table shows the deviation caused by some typical gases or vapours. The
stated values refer to the distance. Positive values mean that the measured distance is too high,
negative values that the measured distance is too small.
Gas phase
Temperature
1 bar/14.5 psig
10 bar/145 psig
50 bar/725 psig
Air/Nitrogen
20 °C/68 °F
0.00 %
0.22 %
1.2 %
Air/Nitrogen
200 °C/392 °F
0.00 %
0.13 %
0.74 %
Hydrogen
20 °C/68 °F
-0.01 %
0.10 %
0.61 %
Hydrogen
200 °C/392 °F
-0.02 %
0.05 %
0.37 %
Water (saturated
steam)
100 °C/212 °F
0.20 %
-
-
Water (saturated
steam)
180 °C/356 °F
-
2.1 %
-
Ambient conditions
Ambient, storage and transport tempera-
ture
-40 … +80 °C (-40 … +176 °F)
Process conditions
For the process temperature and the vessel pressure, you also have to note the specifications on
the type label! Always the lowest value is applicable!
12)
Incl. non-linearity, hysteresis and non-repeatability.
13)
Relating to the nominal measuring range, in the temperature range -40 … +80 °C .
