A bourdon tube is best described as which of the following?

• A. A curved metal tube that deforms under pressure changes
• B. A flat plate that deflects with temperature
• C. A ceramic sensor that expands with heat
• D. A wire that stretches with voltage

Answer: (A)

A bourdon tube converts pressure into mechanical movement using a hollow curved metal tube. When internal pressure rises, the curved shape tends to straighten, causing a measurable displacement at the tube’s end that’s linked to a pointer or other mechanism. This deformation happens specifically because the tube is curved and hollow, so pressure changes push against the curvature and produce a visible motion. It’s not just a temperature-facing element, not a ceramic thermal expansion sensor, and not a wire that stretches with voltage, so the curved metal tube that deforms under pressure changes is the correct description.