What device can be used to determine flow pressure at the opening of a smooth bore orifice?

The Pitot tube is specifically designed to measure fluid flow velocity, which correlates with flow pressure at an orifice, such as a smooth bore opening used in firefighting applications. When properly placed in the fluid stream, the Pitot tube captures the dynamic pressure exerted by the fluid, allowing the operator to calculate the flow pressure.

The other devices serve different functions. A manometer measures static pressure or liquid levels, not directly applicable in this situation. A hydraulic gauge measures pressure in a hydraulic system, but does not provide the specific flow measurements at the orifice. A flow meter measures the volume of liquid passing through a system over time, but it does not directly relate flow pressure at the opening of an orifice. Thus, the Pitot tube is the most appropriate choice for determining flow pressure at a smooth bore orifice.