VEGA VEGADIF 34 … 51 - Manual (Page 46)

46 VEGADIF 34 … 51
20094-EN-030731
For mounting to horizontal pipelines, buildup
on the isolating diaphragm in the form of solids
or materials sticking to the diaphragm should
be avoided. We therefore recommend install-
ing the flange connections on top of the pipe-
line.
- +
Installation connections
1 Inlet valves
2 Transmitter
3 Vent or drain valves
4 Block valves
5 Pressure tapping point
6 Vent screw
7 Separator for impurities
8 Blow down valves
Note
The described connections are recommended
measurement set-ups. For other measurement
set-ups, various VDE/VDI regulations or DIN
standards (e.g. VDE/VDI 3512) give additional
installation instructions.
Special instructions for VEGADIF 51
6
4
1
5
+
7
8
-
3
2 +
5.4 Level measurement
Installation on open vessels
On an open vessel the level is measured via
the hydrostatic pressure. „Open vessel“
means all vessels with an atmospheric pres-
sure above the liquid.
VEGADIF takes the hydrostatic pressure on
the plus side via a flange diaphragm, via an
impulse line or an isolating diaphragm. The
atmospheric pressure is taken via the minus
side.
The hydrostatic pressure corresponds to the
level measured from the center of the flange
diaphragm or the center of the impulse line
multiplied by the specific gravity of the prod-
uct and the acceleration due to gravity. Be-
cause the atmospheric pressure acts on the
plus side as well as on the minus side of
VEGADIF, it is compensated in the differential
pressure generation.
∆
p = p
hydr
=
ρ
• g • h
∆
p, p
hydr
: hydrostatic pressure [Pa]
ρ
: Density [kg/m 3 ]
g: Acceleration due to gravity [m/sec 2 )
h: Level [m]