pressure measurement instrument

Pitot Tube:
is a pressure measurement instrument used to measure fluid flow velocity. The pitot tube was invented by the French engineer Henri Pitot in the early 18th century[1] and was modified to its modern form in the mid-19th century by French scientist Henry Darcy.
It is widely used to determine the airspeed of an aircraft, water speed of a boat, and to measure liquid, air and gas flow velocities in industrial applications. The pitot tube is used to measure the local flow velocity at a given point in the flow stream and not the average flow velocity in the pipe or conduit.
A slender tube aligned with the flow (Figs. 6.29g and 6.30) can
Measure local velocity by means of a pressure difference. It has sidewall holes to measure the static pressure ps in the moving stream.
Hole in the front to measure the stagnation pressure p0, where the stream is decelerated to zero velocity.
Instead of measuring p0 or ps separately, it is customary to measure their difference with, say, a transducer, as in Fig. 6.30.
The flow around the probe is nearly frictionless and Bernoulli’s relation, applies For incompressible flow:

P_s/?+(?v_s?^2/2g)+z_s= P_o/?+(?v_o?^2/2g)+z_o
Where: Ps, vs, and zs= static pressure, velocity, and elevation at the pipe flow.
Po, vo, and zo= pressure, velocity, and elevation at the stagnation point. vo= zero.
Assuming that zs=zo. calculating the velocity at stream flow:
v=?(2g ((p_o-p_s ))/?)