Hydrostatic Level Measurement

Hydrostatic Level Measurement

Hydrostatic level measurement provides continuous level measurement in liquid applications using pressure sensors. The instrument measures the pressure generated by the liquid column (hydrostatic head) and converts that pressure to level using density and gravitational assumptions. This can be implemented as a single gauge/absolute sensor (open tanks) or as differential pressure (pressurized vessels), depending on the process configuration.

The approach is valued for robustness against surface effects: foam, agitation, and headspace vapor typically have limited impact because the sensor references pressure at a fixed elevation rather than surface reflections. Hydrostatic measurement can also be packaged with remote seals and chemical-resistant materials for aggressive media. In many facilities, it remains a practical option for both small and large vessels because it is conceptually direct and integrates cleanly into standard analog or digital signal architectures.

Accuracy is coupled to density. If product density varies materially with temperature, concentration, entrained gas, or phase changes, level accuracy will drift unless density compensation or recalibration is applied. Installation details matter as well: venting for gauge sensors, impulse line layout for DP, condensation management, and avoidance of plugging in dirty service are often the difference between stable operation and chronic maintenance.

Common applications include water and wastewater wet wells, reservoirs, tanks and basins; chemical storage and day tanks; and many food and beverage utility services. In pressurized vessels, DP configurations are used for level in separators and process tanks. Where interfaces are present, hydrostatic methods can be used when density relationships are well understood and the mechanical layout supports stable reference pressure.

Selection is driven by pressure range (including overpressure scenarios), process temperature, material compatibility, and whether remote seals are needed to isolate the sensor from plugging or corrosion. Commissioning typically establishes reference points (empty/zero and span) and verifies vent/reference integrity. Long-term reliability improves when impulse/vent paths are treated as maintainable assets rather than “set-and-forget” plumbing.

George E. Booth Co., an exclusive authorized representative of sales and service for Endress+Hauser.