VEGA VEGAFLEX 86 4 … 20 mA_HART two-wire Coax probe With SIL qualification - Manual (Page 18)

18
4 Mounting
VEGAFLEX 86 • 4 … 20 mA/HART two-wire
44231-EN-130823
1
2
Fig. 8: Mounting of the instrument on insulated vessels.
1 Temperature insulation
2 Ambient temperature on the housing
Vapours, superimposed gases, high pressures and temperature dif-
ferences can change the spreading speed of radar impulses.
There are two possibilities to correct these deviations.
Corrective value in the process control system
In the technical data under "Influence of superimposed gas and pres-
sure on accuracy" you can find a table with deviation values in some
typical gases or in steam.
In the control system (DCS) you can correct the measurement results
of the VEGAFLEX 86 with these values.
The prerequisite is constant temperature and pressure in the vessel.
Automatic correction via the reference distance
The VEGAFLEX 86 can be equipped optionally with a running time
correction via reference distance. The probe can carry out an auto-
matic running time correction with it.
The reference point must hence not be overfilled. The upper dead
band is hence 450 mm (17.7 in).
Steam boiler applications