Endress+Hauser Deltapilot S DB50 - Page 7

Deltapilot S
Endress+Hauser 7
Level measurement in closed tanks with pressure overlay
You can determine the differential pressure in tanks with pressure overlay using two Deltapilot S probes. The
pressure measured values of the two probes are sent to a signal processing unit such as Endress+Hauser RMA
or a PLC. The signal processing unit or PLC determines the difference in pressure and uses this to calculate the
level and the density where necessary.
P01-DB5xxxxx-15-xx-xx-xx-007
Level measurement in a closed tank with pressure overlay
1 Probe 1 measures the total pressure (hydrostatic pressure and top pressure)
2 Probe 2 measures the top pressure
3 The signal processing unit determines the difference in pressure and uses this to calculate the level
Note!
• When selecting the Deltapilot S probes, make sure you select large enough measuring ranges
(→ see example).
• The measuring diaphragm of probe 2 must not be flooded. This generates additional hydrostatic pressure
which distorts the measurement.
• The ratio of hydrostatic pressure to top pressure should be max. 1:6.
Example:
• Max. hydrostatic pressure = 600 mbar
• Max. top pressure (probe 2) = 300 mbar
• Max. total pressure, measured with probe 1 = 300 mbar + 600 mbar = 900 mbar
⇒ Measuring cell to be selected: 0 to 1200 mbar
• Max. pressure, measured with probe 2: 300 mbar
⇒ Measuring cell to be selected: 0 to 400 mbar
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