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I wish I knew how a bubbler level transmitter works!
The bubble application is one of the many ways to measure level with a differential pressure transmitter (DP) device. While not common, this method still pops up here and there.
When I was learning instrumentation, I learned to apply this method in grounded tanks, where you don’t have easy access to the bottom. However, as non-contact solutions have grown in popularity, bubblers have waned. Regardless, I’ll tell you a little more about this type of differential pressure transmitter.
The system has a dip tube submerged in the tank with a supply of an inert gas or air. The DP device has its high-pressure cell connected to the dip tube to measure the back pressure. You can find the level using the known density and the back pressure, also called hydrostatic back pressure.
With a low level in the tank, you won’t have resistance on the gas, so the transmitter will measure zero in the dip tube. When the level rises, the resistance on the gas also increases, and the transmitter will start to measure a higher back pressure. Once the level reaches 100 percent, the dip tube will contain all the air, and the differential pressure transmitter will measure it. You can learn more about level measurement here!