The DP Transmitter measures flow by detecting which signal?

• A. The velocity of the fluid in the pipe.
• B. The density of the fluid.
• C. The pressure difference between high and low pressure connections.
• D. The color of the fluid.

Answer: (C)

A differential-pressure transmitter detects the pressure difference between the upstream (high pressure) and downstream (low pressure) connections. This pressure drop results when fluid flows through a restriction or flow element, and the transmitter converts that differential pressure into an electrical signal that represents flow rate. The velocity of the fluid and the fluid’s color aren’t what the device directly measures, and density affects the relationship between ΔP and flow but isn’t the signal being detected.