Which of the following is NOT a type of velocity measurement instrument?

The thermal mass flow meter is primarily designed for measuring the mass flow rate of gases based on their thermal properties, rather than directly measuring the velocity of the fluid. This instrument operates by determining how much heat is lost as heat is applied to a sensing element submerged in the flow. The amount of heat lost is related to the mass flow rate of the gas, so while it does provide flow information, it does not measure velocity in terms of fluid flow speed directly.

On the other hand, the orifice plate, Pitot tube, and turbine flowmeter are all instruments that measure the velocity of a fluid. The orifice plate achieves this by creating a pressure drop that correlates with velocity, while the Pitot tube measures pressure differences in the flow to calculate velocity. The turbine flowmeter utilizes the rotational speed of blades within the flow stream to determine flow rates, which is also directly related to velocity.