How does a differential pressure transmitter operate, and what is a typical application?

How does a differential pressure transmitter operate, and what is a typical application?

• A. It uses a diaphragm to sense differential pressure.
• B. It uses a diaphragm to sense differential pressure and outputs a signal proportional to that difference; used for flow, level, and filter condition.
• C. It measures absolute pressure with a variable capacitor.
• D. It outputs a voltage only and has no relation to differential pressure.

Answer: (D)

A differential pressure transmitter works by having a sensing element, typically a diaphragm, that deflects in response to the pressure difference between two ports. The small deflection is converted by the transducer into an electrical signal that is proportional to that pressure difference, usually a current signal such as 4-20 mA. This design lets you monitor changes in ΔP remotely and accurately. Typical uses exploit how ΔP relates to process variables: the pressure drop across a flow element (like an orifice plate) tells you flow rate; the hydrostatic ΔP between two heights in a vessel relates to level; and the ΔP across a filter changes as the filter becomes dirty, signaling when to replace it. The option that matches this description correctly notes both the diaphragm sensing differential pressure and the signal output proportional to the difference, with applications in flow, level, and filter condition. The other statements are incomplete or inaccurate: a diaphragm alone describes sensing without specifying the proportional signal; measuring absolute pressure with a variable capacitor describes a different type of sensor; and claiming it outputs only a voltage with no relation to differential pressure contradicts the fundamental function of a DP transmitter.

A differential pressure transmitter works by having a sensing element, typically a diaphragm, that deflects in response to the pressure difference between two ports. The small deflection is converted by the transducer into an electrical signal that is proportional to that pressure difference, usually a current signal such as 4-20 mA. This design lets you monitor changes in ΔP remotely and accurately.

Typical uses exploit how ΔP relates to process variables: the pressure drop across a flow element (like an orifice plate) tells you flow rate; the hydrostatic ΔP between two heights in a vessel relates to level; and the ΔP across a filter changes as the filter becomes dirty, signaling when to replace it.

The option that matches this description correctly notes both the diaphragm sensing differential pressure and the signal output proportional to the difference, with applications in flow, level, and filter condition. The other statements are incomplete or inaccurate: a diaphragm alone describes sensing without specifying the proportional signal; measuring absolute pressure with a variable capacitor describes a different type of sensor; and claiming it outputs only a voltage with no relation to differential pressure contradicts the fundamental function of a DP transmitter.