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🔋college physics i – introduction review

Venturi Meters

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Venturi meters are devices used to measure the flow rate of fluids, such as liquids and gases, by taking advantage of the Venturi effect. The Venturi effect describes the decrease in fluid pressure that occurs when a fluid flows through a constricted section of a pipe or channel, as described by Bernoulli's principle.

5 Must Know Facts For Your Next Test

  1. Venturi meters are a type of differential pressure flow meter, meaning they measure the difference in pressure between two points in the flow to determine the flow rate.
  2. The constriction in a Venturi meter causes the fluid to speed up, which results in a decrease in pressure at the constricted section, as described by Bernoulli's principle.
  3. By measuring the pressure difference between the inlet and the constricted section, the flow rate can be calculated using the Venturi equation, which relates the pressure drop to the volumetric flow rate.
  4. Venturi meters are widely used in industrial applications, such as in the measurement of natural gas, steam, and other process fluids, due to their simplicity, reliability, and ability to handle a wide range of flow rates.
  5. Venturi meters have no moving parts, making them less prone to wear and tear compared to other flow measurement devices, such as turbine meters or orifice plates.

Review Questions

  • Explain how the Venturi effect is utilized in Venturi meters to measure fluid flow rate.
    • The Venturi effect describes the decrease in fluid pressure that occurs when a fluid flows through a constricted section of a pipe or channel, as described by Bernoulli's principle. In a Venturi meter, the fluid is forced to flow through a constriction, causing its speed to increase and its pressure to decrease. By measuring the difference in pressure between the inlet and the constricted section, the flow rate of the fluid can be calculated using the Venturi equation, which relates the pressure drop to the volumetric flow rate.
  • Compare and contrast Venturi meters with other types of differential pressure flow meters, such as orifice plates, in terms of their advantages and disadvantages.
    • Venturi meters and orifice plates are both types of differential pressure flow meters, but they have some key differences. Venturi meters have a gradually constricted section, which results in a smaller pressure drop compared to the more abrupt constriction of an orifice plate. This lower pressure drop makes Venturi meters more efficient and less prone to wear and tear, as they experience lower shear forces on the fluid. Additionally, Venturi meters have no moving parts, making them more reliable and requiring less maintenance than orifice plates. However, orifice plates are generally less expensive to manufacture and install, making them a more cost-effective option in some applications.
  • Evaluate the suitability of Venturi meters for different types of fluid flow measurement applications, considering factors such as flow rate range, fluid properties, and installation requirements.
    • Venturi meters are versatile and can be used to measure the flow rate of a wide range of fluids, including liquids, gases, and even slurries. They are particularly well-suited for applications that require the measurement of high-volume, high-velocity flows, such as in the natural gas, steam, and petrochemical industries. Venturi meters can handle a wide range of flow rates and are less affected by changes in fluid viscosity or density compared to other flow measurement devices. Additionally, the lack of moving parts and the gradual constriction design make Venturi meters more reliable and easier to install than some alternatives. However, the higher initial cost and the need for a longer straight pipe section upstream and downstream of the meter may limit their use in some applications with space constraints.