In Differential Pressure Devices, what does an orifice plate do?

An orifice plate is designed to create a restriction in the flow within a pipe, which allows for the measurement of differential pressure across the plate. This drop in pressure can be utilized to calculate flow rates in various applications. The orifice plate's design inherently causes physical wear over time due to the constant friction and turbulence experienced by the flowing fluid, especially in situations where the fluid contains particulates or is subject to high flow velocities.

In the context of the other options, the gradual change in diameter mentioned in the first choice is found in devices like venturi meters rather than in orifice plates, which create a more abrupt change in flow area. The third option involving the measurement of fluid velocity is closely related but does not capture the essence of an orifice plate’s main function; rather, it measures pressure drop to infer flow rate. The fourth choice about filtering out solids misrepresents the function of an orifice plate, as it is not designed to serve as a filter but rather as a flow measurement device.