Pitot Tube , Construction , Working

Introduction :

Pitot Tube is a device used to measure the fluid flow measurement invented by henri pitot a French Engineer in 18th century .

It is also known as pitot probe or insertion meter . 

Construction :

- It Consist of two hollow tubes that sense Pressure at different places within the pipe .

- This hollow tubes can be mounted separately in a pipe or installing together in one casing as a single device .

- One tube measures the stagnation or impact pressure and another tube measures only static Pressure and another tube measures only static Pressure usually at the wall of pipe .

Working :

- When a solid body is kept centrally , a stationary in a pipeline with the flowing fluid , the velocity of the fluid start reducing ( at the same time the Pressure Fluid increases due to the conversion of kinetic energy into Pressure Energy ) due to the Pressure Of the Body at directly in front of the solid body , the velocity becomes zero . the Point is known as the stagnation point  .

- the Fluid Flow can be measured by measuring the difference between the Pressure measure at the normal flow line (static Pressure) and the stagnation Point ( stagnation Pressure ) .

-  Measuring the static Pressure and the impact Pressure are connected to the Proper differential Pressure meter for the determination of the flow velocity and thus the flow rate .

-  The Equation of the velocity is derived by applying Bernoulli's Principle ; the final equation is given below :

v = SQRT( 2gh ) 

g=  acceleration due to gravity .

Actual Velocity :

Va = Cv SQRT ( 2gh ) .

Cv =  Coefficient velocity of pitot tube .