Which of the following are considered velocity instruments?

Velocity instruments measure the speed of a fluid moving through a conduit, and they typically rely on principles that relate flow velocity to other physical properties or phenomena. Ultrasonic and Pitot Tube meters are both established technologies used for this purpose.

Ultrasonic flow meters work by sending and receiving ultrasonic sound waves through the fluid. The difference in the time it takes for these waves to travel upstream versus downstream can be directly related to the flow velocity of the fluid. This allows for precise measurement of flow rates based on the speed of sound in the moving fluid.

Pitot tube devices work on the principle of measuring the difference between static and dynamic pressures in a fluid flow. By creating a pressure differential using the tube positioned at an angle to the flow, the velocity of the fluid can be calculated through Bernoulli's equation. This method is widely used in various applications for measuring air and liquid velocities.

Both of these instruments validate their categorization as velocity meters based on their operational principles focused on determining fluid speed, making them ideal candidates for this classification.