VEGA VEGAFLEX 81 4 … 20 mA_HART two-wire Coax probe With SIL qualification - Manual (Page 77)

77
12 Supplement
VEGAFLEX 81 • 4 … 20 mA/HART two-wire
44216-EN-130823
L
0
-2 mm (-0.079 ")
2 mm (0.079 ")
10 mm (0.394 ")
5 mm (0.197 ")
-5 mm (-0.197 ")
0,15 m (5.906 " )
0,1 m (3.937 " )
0,05 m
(1.97 ")
0,1 m
(3.937 ")
1 1
Fig. 40: Deviation VEGAFLEX 81 in coax version in oil
1 Dead band - no measurement possible in this area
L Probe length
Repeatability ≤ ±1 mm
Specification for safety accuracy (SIL) Siehe Safety Manual
Variables influencing measurement accuracy
Specifications for the digital measured value
Temperature drift - Digital output
±3 mm/10 K relating to the max. measuring range or
max. 10 mm (0.394 in)
Additional deviation through electromag-
netic interference acc. to EN 61326
< ±10 mm (< ±0.394 in)
Specifications apply also to the current output 8)
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 %
8) Also for the second current output (optional)