VEGA VEGAFLEX 81 Modbus and Levelmaster protocol User Manual
Page 77
77
11 Supplement
VEGAFLEX 81 • Modbus and Levelmaster protocol
41828-EN-130314
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
4)
≤ 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.
The measurement error from the process conditions is in the specified pressure and temperature
range of below 1 %.
Process pressure
Ʋ Process fitting with PPS GF 40
-1 … 6 bar/-100 … 600 kPa (-14.5 … 87 psi), depending
on the process fitting
Ʋ Process fitting with Al
2
O
3
-1 … +40 bar/-100 … +4000 kPa (-14.5 … +580 psig),
depending on the process fitting
Vessel pressure relating to the flange
nominal stage
see supplementary instructions manual "Flanges ac-
cording to DIN-EN-ASME-JIS"
Process temperature (thread or flange temperature)
Ʋ PPS GF 40
-40 … +80 °C (-40 … +176 °F)
4)
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).