Which of the following meters typically measures flow directly through bending mechanisms?

Answer: B — Spring probe

The correct choice is the spring probe meter, which operates on the principle of measuring flow by using a flexible probe that bends with the flow of the liquid. As the fluid passes through the meter, the force exerted on the probe causes it to flex. The extent of this bending is directly related to the flow rate of the fluid, allowing for an accurate measurement. Paddlewheel meters, while effective in measuring flow, utilize a different mechanism where a paddle affixed within the flow rotates in response to the water current. This rotation then correlates to a flow measurement, which is not based on bending but rather on rotational motion. Centrifugal meters typically measure flow based on the velocity of the fluid moving through a rotating element and resultant pressure differentials, rather than any bending mechanism. Rotary meters operate using a rotating chamber where the flow of fluid causes mechanical movement, leading to flow measurement, again not involving bending as the primary mechanism. In summary, the flexibility and response of the spring probe to fluid dynamics make it suitable for measuring flow through bending, setting it apart from the other types of meters listed.