What parameters can be measured with a DP cell?

• A. Level and flow
• B. Pressure and temperature
• C. Volume and density
• D. Mass and velocity

Answer: (A)

A differential pressure (DP) cell provides a signal that represents the pressure difference between two points. This difference can be used to infer either level or flow, depending on how the DP is applied.

For level, the pressure difference in a liquid column equals the hydrostatic head: ΔP = ρ g h. If you know the liquid density and gravity, the measured ΔP directly corresponds to the liquid height, giving you level.

For flow, placing the DP cell across a restriction (like an orifice or venturi) creates a pressure drop that relates to the flow velocity through the restriction. With proper calibration, the DP measurement translates into flow rate.

A DP cell does not directly measure absolute pressure or temperature, nor does it directly provide volume, density, mass, or velocity without additional calculations or sensors.