Hydrostatic Level Measurement

Hydrostatic Level Measurement

Hydrostatic level measurement uses pressure as a proxy for liquid head. By measuring the pressure at a known reference point (often near the bottom of a tank or in a submersible installation), level is calculated using the relationship between pressure, density, and height. The method is widely applied for continuous measurement in liquids, pastes, and sludges, including open basins and sumps.

The measuring principle is based on the proportionality of hydrostatic pressure to liquid column height (p = ρ·g·h). A pressure transmitter or submersible probe senses the pressure exerted by the process media; with density known or compensated, the signal converts directly to level. For pressurized tanks, differential pressure configurations can reference vapor space pressure to isolate true hydrostatic head.

Hydrostatic measurement is beneficial for its robustness and directness. It is not dependent on surface reflectivity, foam, or vapor space conditions, and it is well suited to narrow wells, sumps, and vessels where non-contact beams may be obstructed. With appropriate diaphragm seal and materials selection, the method can be applied in corrosive or hygienic services while maintaining a stable pressure signal.

Typical applications include water and wastewater basins, lift stations, river and reservoir level monitoring, sludge tanks, and process vessels containing liquids with stable density. It is also used in chemical and utility services where continuous level is required and where mechanical simplicity and straightforward troubleshooting are desired.

Key selection considerations include density variability (especially with temperature or concentration changes), venting strategy for gauge measurements, and protection against plugged impulse lines or diaphragm fouling. Remote seals, capillaries, or flush diaphragms may be required for viscous, solids-laden, or corrosive media. Installation should also address overpressure, vacuum conditions, and any required functional safety or hazardous-area constraints.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.