A single flange differential pressure level transmitter for open tanks is used to measure liquid level from the hydrostatic pressure at the lower tank connection. Because the tank is open to atmosphere, the top side pressure is usually stable and does not need complex compensation.
This makes open tank applications one of the most common and practical uses for single flange DP level transmitters. The flange diaphragm is installed near the lower side of the tank, and the transmitter converts liquid column pressure into a level signal.
Why Open Tanks Are Suitable
Open tanks are usually easier for DP level measurement because the liquid surface is not under changing gas pressure. The transmitter only needs to measure the pressure created by the liquid height. This is why a single flange structure can often work well.
Typical open tank applications include water tanks, chemical storage tanks, wastewater pits, open process vessels, mixing tanks, and some atmospheric storage tanks. If the medium is clean and non-corrosive, a simple level solution may be enough. If the medium is corrosive, sticky, or dirty, the single flange diaphragm structure becomes more useful.
Key Selection Points
For open tank level measurement, the most important selection factor is not only tank height. The supplier must know what pressure the liquid column will create and whether the flange diaphragm material can withstand the medium.
Buyers should confirm:
- Liquid density
Density directly affects the DP range. The same height of water and oil creates different pressure. - Measuring height
The required measuring span may be different from the full tank height. - Flange connection
Flange size, pressure rating, sealing face, and material must match the tank nozzle. - Medium condition
Corrosive, viscous, dirty, or crystallizing liquids may need special diaphragm or flange materials. - Installation position
The transmitter should be installed where the diaphragm can sense liquid pressure correctly and remain maintainable.
Do Not Ignore Density
In open tanks, density is often the most easily missed parameter. Buyers may provide tank height but forget to provide liquid density. If the transmitter is ranged based on water but the actual liquid is lighter or heavier, the level reading may be incorrect.
If the liquid density changes with temperature or concentration, this should also be mentioned. For many chemical and process liquids, density is not always constant.
Conclusion
A single flange differential pressure level transmitter is a practical solution for open tank level measurement when liquid density, measuring height, flange connection, material, and installation position are clear. It is especially useful when the medium requires a flush diaphragm or diaphragm seal contact surface.
SIY Electric can help configure single flange DP level transmitters for open tanks, water tanks, chemical tanks, wastewater pits, and atmospheric vessels.
