Inside a pressure gauge, which component acts as a flexible C-shaped tube?

• A. Capillary
• B. Bourdon tube
• C. Diaphragm
• D. Seal

Answer: (B)

The key thing here is that the Bourdon tube acts as the flexible C-shaped sensing element in a pressure gauge. This hollow, curved tube tends to straighten when pressure inside increases. That tiny straightening motion is transferred through a linkage to the pointer, producing a reading. A capillary is just a narrow tube used to transmit pressure, not the bending element; a diaphragm is a flat flexible membrane that deforms under pressure, not a curved tube; and a seal’s job is to prevent leaks, not to sense pressure. So the Bourdon tube is the flexible C-shaped component that converts pressure into motion.