In a recent article published in CONTROL magazine author and writer Paul Miller makes the point that hydrostatic head pressure measurement is still a most common method for measuring the level of a fluid in a tank. He makes other points too, more important in his article than here. The point I wish to make here is that this technology for the level measurement of fluid in a tank has been around for many years and is a simple and economical way to measure tank levels, while its "flash" is far less than newer technologies like radar.
Let's take a quick look at how pressure or differential pressure transmitters are used to measure the level of a fluid in a tank. Why type when I can reference you to a perfectly fine tutorial from Wikipedia so follow this link. Some application issues affecting the use and performance of hydrostatic level measurement include the cleanliness of the fluid, the corrosiveness of the fluid and how stable the specific gravity or density of the fluid is. Like other technologies used for level measurement of liquids, there are limitations.... which is why so many technologies exist today and they are all viable in their own right.... EXCEPT for using ultrasonic to measure continuous level of powders and other bulk solids... No No No!
Really though... please read Paul's article "Pressure-Based Level Measurements Keep Getting Better and Better" because it is well written and a great short tutorial on this subject (it also keeps me from having to write it for you LOL). It's great and a reminder how these devices work well and some of their limitations.
I went back and took a look at the most recent market study report I have available. Hydrostatic pressure based level devices represent about 48% of all continuous level measurement devices bought each year! That's huge!
Joe
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