What exactly is the "bubble-in" principle and how does it work?

FAQ - Nimbus

1. What are the advantages to "bubble-in" technology?
2. Q: What exactly is the "bubble-in" principle and how does it work? A: A piston pump inside the instrument enclosure generates compressed air, which flows through a dedicated line into the bubble chamber at programmable intervals, where it bubbles out uniformly into the groundwater. Depending on the groundwater level (h) above the bubble chamber orifice, an air pressure equal to the hydrostatic pressure (p) is established inside the measuring tube. p = ρ · g · h ρ = specific gravity of water g = gravitational acceleration m / sec 2. Assuming a constant liquid density, there is a linear relationship between the water level to be measured and the air pressure inside the measuring tube. The bubble-line pressure and the barometric pressure are measured concurrently by an absolute pressure-measuring cell inside the instrument enclosure. The water level is calculated as the difference between the two signals. This measuring method prevents a potential zero-point drift of the measuring cell from influencing the accuracy of the instrument. The usage of an absolute pressure-measuring cell makes the instrument completely unaffected by humidity and condensation.
   
   
3. Is the Nimbus better suited for ground or surface water level measurement?
4. Is the Nimbus SDI-12 Compliant?
5. What types of communication or telemetry does the Nimbus offer?