VEGA VEGADIF 65 Foundation Fieldbus - Manual (Page 28)

28
4 Mounting
VEGADIF 65 • Foundation Fieldbus
36130-EN-130417
The max. adjustment is carried out for the differential pressure meas-
ured at density 1.2:
Δp = ρ • g • h
= 1200 kg/m³ • 9.81 m/s
2 • 0.3 m
= 3531 Pa = 35.31 mbar
= ∆p
h g
+
–
0,3 m
Fig. 27: Measurement setup with density measurement
In a vessel with varying level, an interface measurement with a dif-
ferential pressure transmitter can be realized. The connection on the
vessel is carried out via a chemical seal on two measuring points.
An interface measurement is only possible if the densities of the two
products remain the same and the interface is always between the
two measuring points. The total level must always be above the upper
measuring point.
This density measurement functions with open but also with closed
vessel.
Example for an interface measurement:
Distance between the two measurement points: 0.3 m
Min. density: 800 kg/m³
Max. density: 1000 kg/m³
The min. adjustment is carried out for the differential pressure occur-
ing with density 0.8:
Δp = ρ • g • h
= 800 kg/m³ • 9.81 m/s • 0.3 m
= 2354 Pa = 23.54 mbar
The max. adjustment is carried out for the differential pressure occur-
ing with density 1.0:
Δp = ρ • g • h
= 1000 kg/m³ • 9.81 m/s • 0.3 m
= 2943 Pa = 29.43 mbar
3. Mount VEGADIF 65 below the lower chemical seal
4. The ambient temperature should be the same for both capillaries
Interface measurement