When measuring the mass flow in gases, its necessary to considerate the pressure reduction and change in density of the fluid. = upstream and downstream pipe diameter (m, ft)Ĭan be modified to mass flow for fluids by simply multiplying with the density: = orifice, venturi or nozzle inside diameter (m, ft) The pressure recover to a pressure level lower than the pressure before the obstruction and adds a head loss to the flow. After the metering device the velocity will decrease to the same level as before the obstruction. The viscous effect is usually expressed in terms of the non-dimensional parameterĭue to the Benoulli and the Continuity Equation the velocity of the fluid will be at it's highest and the pressure at the lowest in ' ' is the minimum jet area that appears just downstream of the restriction.

Is a function of the jet size - or orifice opening - the , the flow rate can be determined by measuring the pressure differenceĬan be modified with a discharge coefficient: The equation can be adapted to vertical flow by adding elevation heightsĪssuming uniform velocity profiles in the upstream and downstream flow - the To understand orifice, nozzle and venturi meters it is necessary to explore the Bernoulli Equation.Īssuming a horizontal flow (neglecting the minor elevation difference between the measuring points) the The downstream pressure after an obstruction will be lower than the upstream pressure before.

1.5 dredge nozzle