VEGA VEGADIF 34 … 51 - Manual (Page 50)

50 VEGADIF 34 … 51
20094-EN-030731
VEGADIF 44, 45
The transmitter must be mounted to the vessel
in such a way that the isolating diaphragm is
completely covered by the medium (even at
min. level).
The pressure tapping point for the total pres-
sure can be at the bottom of the vessel or at a
defined height. The pressure tapping point for
the overlaid pressure must be above the max.
level. The lower pressure tapping point is
connected to the plus side, the upper tapping
point to the minus side of the transmitter.
The transmitter receives the total pressure on
the plus side via the flange isolating dia-
phragm, the overlaid pressure on the minus
side via the impulse line and the process
connection.
Standard connection
Example VEGADIF 45:
Transmitter directly flanged
1 Transmitter
2 Block valve
3 Separator for impurities
4 Blow down valve
5 Vent or drain valve
2
3
1
4
5
h
1
h
2
∆ p
h = ––––––
ρ • g
Installation connections
Installation on closed vessels with overlaid
steam pressure and heated comparative
column
This installation is a variant of the one de-
scribed previously. In this case, the conden-
sate column is covered by a tube (of larger
nominal width diameter) which is filled with the
measured product and acts as a communicat-
ing pipe. Through the resulting temperature
equalisation, the density is the same in both
columns. The outer pipe must therefore be
insulated - not the adjustment vessel however
(the condensate heat must be dissipated).
This arrangement is preferred for measuring
substances with higher density because it
delivers more accurate measurement results.
The previously described technical conditions
also apply to this measurement set-up.
The VDE/VDI regulations 3512 of various DIN
standards give more detailed information on:
- layout and configuration of throttles and
impulse lines
- selection of components for corrosive medi-
ums.
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1 Inlet valves
2 Equalization valves
3 Transmitter
4 Vent or drain valves
5 Block valves
6 Blow down valves
7 Separator for impurities