Which sensor can use differential pressure to obtain level and flow measurements?

• A. Temperature Sensor
• B. Wind Sensor
• C. Rain Sensor
• D. Pressure Sensor

Answer: (D)

Differential pressure lets you infer how high a liquid column is or how fast it’s moving by comparing the pressure at two points in the system. The pressure at depth increases with height (P ≈ ρgh), so measuring the difference between two points along the column gives level. For flow, the pressure drop across a restriction (like an orifice or venturi) relates to the flow rate through that element.

A pressure sensor, especially a differential pressure sensor, is what provides that pressure difference data. It’s designed to detect the difference between two pressures and convert it into an electrical signal you can read. The other sensors—temperature, wind, and rain—measure unrelated quantities and don’t provide the required pressure-difference information for level or flow calculations.