Venturi MeterVenturi MeterByBy

Alex TurnerAlex Turner&&

Mick LockMick Lock

What is it?What is it?

A pipe that has a A pipe that has a cone that narrows cone that narrows and then gradually and then gradually returns to the original returns to the original diameter of the pipe.diameter of the pipe.

There are pressure There are pressure sensors or pipes sensors or pipes before the before the constriction and at constriction and at the point of the point of constriction.constriction.

What does it do?What does it do?

The venturi meter measures flow The venturi meter measures flow raterate

A venturi meter constricts the flow of A venturi meter constricts the flow of a fluid and measures the pressure a fluid and measures the pressure before the constriction and at the before the constriction and at the point of constriction.point of constriction.

The meter is read by working out the The meter is read by working out the pressure head which is the difference pressure head which is the difference of the two readings and using the of the two readings and using the values in a formula.values in a formula.

Equations and FormulaeEquations and Formulae

The Bernoulli The Bernoulli Equation Equation

wherewhere

p = pressurep = pressure

ρ = density of liquidρ = density of liquid

v = flow velocityv = flow velocity

)(2

21

2221 vvpp

Equations and FormulaeEquations and Formulae

Working out the flow rateWorking out the flow rate is the volumetric flow rateis the volumetric flow rate and are the cross sectional diametersand are the cross sectional diameters is the pressure headis the pressure head is the discharge coefficient of the pipeis the discharge coefficient of the pipe

bA

hgAA

AAQ m

ba

batheor )1/(2

22

theordactual QCQ

aA

dC

h

Q