Compensating for Atmospheric Pressure When Using a Submersible Transmitter

Compensating for Atmospheric Pressure When Using a Submersible Transmitter

Submersible transmitters are pressure transmitters. How they gauge the level of water or another liquid is based on electrostatic pressure. As the name indicates, submersible transmitters are inserted into the fluid they’ll be measuring. They’ll read the fluid level above the location of the sensor itself.

Hydrostatic pressure is essentially the pressure created per unit area (often measured in psi, or pounds per square inch) at the base of the column of liquid. While we use column of liquid as a term, the actual measurement does not change based on the shape of the container. It relies instead on the density of the liquid being measured.

Now, hydrostatic pressure is affected by atmospheric pressure because atmospheric pressure exerts force upon the fluid’s surface. This would usually change the accuracy of the readings by a submersible transmitter, but there is a way around this. First, let’s explain the effect. Depending on the exposure of the environment in which the liquid is located, changes in weather can also create changes in a transmitter’s accuracy. This isn’t because the transmitter is affected in any direct way, but rather because the atmospheric pressure being exerted upon the surface of the liquid changes the hydrostatic pressure of the liquid itself. In other words, when atmospheric pressure exerts more force upon the surface of a liquid, that hydrostatic pressure within the liquid changes proportionally. Elevation can also have an effect on these measurements, since atmospheric pressure is lesser at higher elevations.

Since hydrostatic pressure is what a submersible transmitter is measuring, there needs to be a way to take atmospheric pressure into account. It’s for these reasons that submersible transmitters incorporate a vented cable that can also gauge atmospheric pressure and compensate for it in the measurements it produces. These vents are also filtered so that they won’t become clogged with debris.

Whether you’re using submersible transmitters in wells, dams, irrigation, sewage and wastewater, lake water or brackish ocean, we’re happy to talk about the science, care, and maintenance behind them and the care we put into thinking up a variety of other environmental conditions that must be compensated for in our products.