A bellows sensor is described as a device with a sensing element that expands and contracts with varying pressure. Which material is specified for this element?

A bellows sensor is described as a device with a sensing element that expands and contracts with varying pressure. Which material is specified for this element?

• A. Stainless steel that expands with temperature
• B. Aluminum plate that deflects with wind
• C. Plastic diaphragm that deforms under vacuum
• D. Flexible copper that expands and contracts with varying pressure

Answer: (D)

A bellows sensor relies on a sensing element that physically flexes in response to pressure differences. The element must be a material that can be formed into a highly compliant, repeatable bellows shape and return to its original form as pressure changes, without fatigue. Flexible copper fits this role well because it is highly ductile and can be shaped into corrugations that expand and contract reliably with pressure. This gives a measurable mechanical displacement tied directly to pressure changes, which is exactly what a bellows sensor uses. The other options miss the essential idea: they either respond mainly to temperature, wind, or vacuum in a way that isn’t the characteristic bellows behavior, or they describe a diaphragm rather than a bellows. Therefore, flexible copper that expands and contracts with varying pressure is the appropriate sensing element.

A bellows sensor relies on a sensing element that physically flexes in response to pressure differences. The element must be a material that can be formed into a highly compliant, repeatable bellows shape and return to its original form as pressure changes, without fatigue. Flexible copper fits this role well because it is highly ductile and can be shaped into corrugations that expand and contract reliably with pressure. This gives a measurable mechanical displacement tied directly to pressure changes, which is exactly what a bellows sensor uses. The other options miss the essential idea: they either respond mainly to temperature, wind, or vacuum in a way that isn’t the characteristic bellows behavior, or they describe a diaphragm rather than a bellows. Therefore, flexible copper that expands and contracts with varying pressure is the appropriate sensing element.