VEGA VEGAFLEX 81 4 … 20 mA_HART two-wire User Manual
Page 86
86
11 Supplement
VEGAFLEX 81 • 4 … 20 mA/HART two-wire
41824-EN-130612
Additional deviation through electromag-
netic interference acc. to EN 61326
< ±10 mm (< ±0.394 in)
Specifications apply also to the current output
7)
Temperature drift - Current output
±0.03 %/10 K relating to the 16 mA span max. ±0.3 %
Deviation on the current output through
analogue/digital conversion
< ±15 µA
Additional deviation through electromag-
netic interference acc. to EN 61326
< ±150 µA
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
Temperature
Pressure
1 bar (14.5 psig)
10 bar (145 psig)
50 bar (725 psig)
Air
20 °C/68 °F
0.00 %
0.22 %
1.2 %
200 °C/392 °F
-0.01 %
0.13 %
0.74 %
400 °C/752 °F
-0.02 %
0.08 %
0.52 %
Hydrogen
20 °C/68 °F
-0.01 %
0.10 %
0.61 %
200 °C/392 °F
-0.02 %
0.05 %
0.37 %
400 °C/752 °F
-0.02 %
0.03 %
0.25 %
Steam (saturated
steam)
100 °C/212 °F
0.26 %
-
-
180 °C/356 °F
0.17 %
2.1 %
-
264 °C/507 °F
0.12 %
1.44 %
9.2 %
366 °C/691 °F
0.07 %
1.01 %
5.7 %
Characteristics and performance data
Measuring cycle time
< 500 ms
Step response time
8)
≤ 3 s
Max. filling/emptying speed
1 m/min
Ambient conditions
Ambient, storage and transport tempera-
ture
-40 … +80 °C (-40 … +176 °F)
Process conditions
For the process conditions, please also note the specifications on the type label. The lowest value
always applies.
7)
Also for the second current output (optional)
8)
Time span after a sudden measuring distance change by max. 0.5 m in liquid applications, max 2 m with bulk
solids applications, until the output signal has taken for the first time 90 % of the final value (IEC 61298-2).