Name: venturi meter flow rate from pressure
Uploaded: 2026-01-30T03:08:31.000Z
Duration: 1 min 16 s
Channel: JoVE

A Venturi meter is installed in a sewage system to measure the wastewater flow rate. If the flow rate is known and viscous effects are negligible, what is the pressure difference indicated by the pressure gauge attached to the flowmeter?
First, calculate the cross-sectional areas of both the pipe and the throat using their respective diameters.
Then, using the continuity equation, determine the velocities at both sections based on the given flow rate.
Since area and velocity are inversely related, the wastewater will speed up as it moves from the larger-diameter pipe into the smaller throat.
Next, apply Bernoulli's equation, which relates the pressure difference between two points in the flow to the change in velocity.
This equation shows that as the velocity increases when the water moves from the larger pipe to the smaller throat, there will be a corresponding pressure drop.
Finally, calculate the pressure difference between the pipe and the throat by substituting the velocities into Bernoulli's equation.
The pressure gauge attached to the flowmeter will indicate the final pressure difference.

bernoulli's equation: problem solving

A Venturi meter is essential for measuring fluid flow rates in pipelines. It utilizes the relationship between fluid velocity and pressure described by Bernoulli's equation. When installed in a sewage system, the Venturi meter accurately determines the wastewater flow rate by measuring pressure differences.
The first step is to compute the cross-sectional areas of the pipe and the Venturi throat to analyze the pressure difference indicated by the pressure gauge. Next, the continuity equation is applied, which states that the volumetric flow rate (Q) remains constant along the pipeline for an incompressible fluid:
<img alt="Continuity equation, Q=A&#8321;V&#8321;=A&#8322;V&#8322;, fluid dynamics, formula." src="/files/ftp_upload/18035/18035_Equation_1.svg" style="text-align: center; height: 12px;" data-altupdatedat="1776139283000" data-alt="Equation 1" />
A1 and A2 are the pipe and throat cross-sectional areas, and V1 and V2 are the fluid velocities at these sections. By rearranging the equation, the velocity at the throat can be expressed as:
<img alt="Fluid dynamics continuity equation, V2=A1/A2V1, formula illustrating flow rate conservation." src="/files/ftp_upload/18035/18035_Equation_2.svg" style="text-align: center; height: 30px;" data-altupdatedat="1776139283000" data-alt="Equation 2" />
Thus, the velocities V1 and V2 can be calculated for a given flow rate.
Bernoulli's equation relates pressure and velocity in an ideal fluid, given by:
<img alt="Bernoulli's equation: fluid dynamics formula, symbolizing pressure and velocity relationship." src="/files/ftp_upload/18035/18035_Equation_3.svg" style="text-align: center; height: 27px;" data-altupdatedat="1776139283000" data-alt="Equation 3" />
Here, P1 and P2 are the pressures in the pipe and throat and &#9076; are the fluid's density. The pressure difference (P1 - P2) can be computed by substituting the velocities V1 and V2 into this equation. This pressure drop (&#916;P), indicated by the pressure gauge, reflects the increase in velocity as the wastewater flows through the narrower throat, consistent with energy conservation.

Bernoulli's Equation: Problem Solving

A Venturi meter is installed in a sewage system to measure the wastewater flow rate. If the flow rate is known and viscous effects are negligible, what is ...

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venturi meter flow rate from pressure

A Venturi meter measures fluid flow rate in a pipeline by using pressure changes and Bernoulli's equation. In a sewage system, it can be used to determine wastewater flow rate by reading the pressure difference across the meter. The narrowed throat makes the fluid speed up, and that change in speed is linked to pressure drop.

The first step is to find the cross-sectional areas of the pipe and the Venturi throat. These areas are needed to interpret the pressure difference shown on the pressure gauge. Next, the continuity equation is applied. For an incompressible fluid, the volumetric flow rate Q stays constant, and the pipe and throat areas are written as A1 and A2 with velocities V1 and V2.

From the continuity equation, the throat velocity can be rearranged and calculated from the flow rate. Once V1 and V2 are known, Bernoulli's equation is used to relate pressure and velocity in an ideal fluid. With the fluid density included, the pressures P1 and P2 in the pipe and throat can be compared to find the pressure difference.

Substituting the velocities into Bernoulli's equation gives the pressure drop, ΔP. That pressure drop is the value indicated by the pressure gauge. It reflects the increase in fluid speed as wastewater moves through the narrower throat, which follows energy conservation.

Venturi Meter Flow Rate from Pressure

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key terms and concepts

See how a Venturi meter uses continuity and Bernoulli's equation to turn pressure differences into wastewater flow rate in a sewage system.

Venturi Meter Flow Rate from Pressure | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

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Venturi Meter Flow Rate from Pressure

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