17
4 Mounting
VEGABAR 86 • Secondary Device for electronic differential pressure
48048-EN-220817
Instruments with absolute pressure have a blind plug mounted
instead of the filter element.
4.3 Combination Primary - Secondary
In principle, any sensor combination within the VEGABAR 80 series is
allowed. The following requirements must be fulfilled:
•
Configuration Primary Device suitable for electronic differential
pressure
•
Pressure type is identical for both sensors, i.e. relative pressure/
relative pressure or absolute pressure/absolute pressure
•
Primary Device measures the higher pressure
•
Measurement setup as shown in the following chapters
The measuring range of each sensor is selected such that it fits the
measuring loop. For this, the max. recommended turn down must be
noted. See chapter "
Technical data
". It is absolutely necessary the
the measuring ranges of Primary and Secondary correspond.
Measurement result = Measured value of Primary (total pres-
sure) - measured value of Secondary (static pressure)
Depending on the application, individual combinations can result, see
following examples:
Data
Application: Level measurement
Medium: Water
Vessel height: 12 m, pressure = 12 m x 1 Kg/m
3
x 9.81 m/s
2
= 1.18 bar
Superimposed pressure: 1 bar
Total pressure: 1.18 bar + 1 bar = 2.18 bar
Instrument selection
Nominal measuring range Primary: 2.5 bar
Nominal measuring range Secondary: 1 bar
Turn Down: 2.5 bar/1.18 bar = 2.1 : 1
Data
Application: Level measurement
Medium: Water
Vessel height: 250 mm, pressure = 0.25 m x 1 Kg/m
3
x 9.81 m/s
2
=
0.025 bar
Superimposed pressure: 350 mbar = 0.35 bar
Total pressure: 0.25 bar + 0.35 bar = 0.375 bar
Instrument selection
Nominal measuring range Primary: 0.4 bar
Nominal measuring range Secondary: 0.4 bar
Turn Down: 0.4 bar /0.025 bar = 16 : 1
The measuring result (level, pressure difference) as well as measured
value Secondary (static or superimposed pressure) are output by the
Example - large vessel
Example - small vessel
Output measured values
