hydrostatic pressure sensor level measurement

Hydrostatic sensors measure pressure at the bottom of the tank and convert it to level based on fluid density. They must be in contact with the liquid. Ultrasonic transmitters measure the time of flight of a sound pulse reflected from the surface—they’re non-contact. Hydrostatic sensors are often preferred when there’s heavy foam, vapor, or dust in the air, because those conditions scatter ultrasonic signals. They also give continuous readings unaffected by surface turbulence if installed in a stilling well.

Standard options are 4–20 mA (two-wire loop powered) with optional HART communication, and RS485 with Modbus RTU protocol. We can also supply voltage outputs (0–5 V, 0–10 V) if your DAQ system requires it. The signal selection depends on cable distance: 4–20 mA handles hundreds of meters without degradation, while RS485 is better for networked installations where you want multiple sensors on a single bus.

Yes, but the material selection is critical. For seawater or brackish water, we typically recommend 316L stainless steel body with a PTFE-jacketed cable. For strong acids or solvents, we move to Hastelloy C-276 or fully PTFE-coated sensors. The cable vent tube also needs a corrosion-resistant design to prevent salt crystal buildup. Tell us the specific media and concentration, and we’ll confirm compatibility from our chemical resistance database.

Drift often comes from three sources: a blocked vent tube in the cable, moisture ingress into the reference side, or thermal cycling that wasn’t fully compensated. Make sure the vent cap is dry and free of dust or insects. Check the cable for kinks or compression that could seal the vent path. If drift persists, the sensor might need a factory recalibration—we can do a bench check and identify whether the issue is a seal failure or an electronics fault.

Usually not, because the sensor is calibrated at the factory for the specified range and temperature limits. However, if the actual fluid density differs significantly from water (1.0 g/cm³), you’ll need to apply a scaling factor in your PLC or controller. For example, in 0.9 g/cm³ oil, a 10-meter column creates only 9 meters of equivalent water pressure, so the raw reading must be divided by 0.9. We provide this density correction formula in the manual, and support can walk you through the setup for Modbus or HART devices.