A venturi meter is an instrument which is to calculates the liquid flow in tubes. This meter works on the principle of **Bernoulli’s equation**. The venturi meter is a flow-measuring instrument that comes with a narrow throat for the conversion of the potential energy of the fluid passing in pipe where devices connected kinetic energy and flow rate are measured.

**Introduction to venturi flow meter**

- A venturimeter is a flow-measuring device that measures liquid flow in a tube. That works based on
**Bernoulli’s equation**. - Venturin tubes come with 72-inch dimensional and can allow 25 to 50 percent more flow than orifice plates of the same pressure droplet.

- It transforms pressure energy into Kinetic energy and measures the flow rate of liquid in the pipe
- It comes with a tube of larger diameter and small constriction in the middle
- Venturi meter operated on the Bernoulli equation such as the velocity of fluid increases when pressure decreases.
- This theorem defines that the cross-sectional area of flow reduces and pressure difference is produced between different part of flow
- It helps to measure the difference for the pressure that helps to get discharge inflow.

**Parts of a Venturi Meter**

**Converging Part**:

- The cone area reduces when water flows. so there is an increase in the speed of water flowing and reduces pressure.

**Throat Diameter**:

- Area is constant in throat diameter when water passes so speed and pressure are also constant values.

**Diverging Part**:

- Area increases when water passes through the cone and speed reduces and pressure decreases

**Venturi Principle**

- This principle explains that as the speed of fluids increases pressure decreases.
- If liquid flows in venturi at a position where cross-sectional area A1 pressure
**P**_{1}, and speed**V**_{1}. - This configuration is based on the potential and kinetic energy of liquid at a single point. Energy is conserved for sealed configuration, which says the addition of KE and PE for the same point is equal to the sum of both at another point.
- if potential energy affects at one point KE will increase at that point. The liquid second point of the venturi has area
**A**_{2}, which is lesser than first area**A**_{1}. - According to the law of conservation, mass is not produced not created and the flow rate of fluid is A1 and equal to area
**A**_{2}. - If A2 is less than A1 liquid flow fast for a saving flow rate at the same value. That increase in speed resulted in a reduction of pressure that operated on Bernoulli’s Theorem. The pressure and cross-sectional area are for two different points and one can measure the speed of the liquid. With the speed of liquid, we can measure the flow rate.
- There is a need of two pressures of venturi and one temperature measure for accurate liquid flow. The pressure is measured at Venturi’s inlet position,
**P**_{1}.

## Benifits Venturi Meter

- It decreases propelling prices.
- It has a low price compare to other venturi meters.
- It has no moving part and it can easily repair if a fault occurs at it.
- There is a need of insignificant square tube space necessities.
- Its brushoff ratio is10:1

- It has a repeatability of ± 0.1%
- It can be based in any location
- Its design is so simple which draws minimum pressure.

**Types of Venturimeter**

**Horizontal Venturimeter**

- This meter comes with horizontal axis flow. The horizontal meter comes with a high kinetic energy value and low potential energy.

**Vertical Venturimeter**

- In this meter, flow is axis vertical and comes with low kinetic energy and high potential energy

**Inclined Venturimeter**

- In this meter flow axis is at an angle and the kinetic and P.E of these fluids is between horizontal and vertical types of meter

## Features

- Now we discuss the features of the venturi flow meter.
- This meter delivers stability, and fidelity, and works for a long time.
- It offers an un-adjusted precision of ±0.75 percent with repeatability of ±0.1 percent.
- Is intended in harmony with the same and iso criteria and it proposes the uppermost “as constructed” correctness.
- It decreases the propelling prices.
- It also offers the deepest level of enduring pressure damage of any venturi smartness, meaningfully fewer than orifice plates.
- It is a customary and exclusive amalgam,
- It provides a long-lasting elucidation for fluids, vapor, mist, and varied mediums.
- With slight alterations, the SSL can be distorted into a bi-steering movement meter.
- It can connect in any location with a negligible square tube.
- It is also recognized as Herschel.
- It working is like an RTD.

## Venturi Meter Specification

- The Line size of the venturi meter range is about 100 mm to 800 mm.
- Accuracy can be from +/-0.25 % to +/-3.0%.
- The flow coefficient value is 0.98 for different values of diameter
- The beta ratio value is 0.3 and 0.75.

## Applications of a Venturi Meter

- It is used for measuring chemical flow in pipelines.
- it is also used for measuring the flow rate of fluid discharged in the pipe
- it is a common part of the waste treatment process for larger-diameter pipes.
- It is also used in industries for measuring pressure and gas quantity and liquids in flow.
- The rate of flow of blood is measured with this device.
- it has features to recover high-pressure

### Advantages of Venturi meter:

- They offer high-accuracy results.
- Its accuracy is not based on temperature and pressure in the pipe.
- It does not have moving components and has low energy losses
- It is used for gases, water, suspended solids chemicals, dirty liquids, etc
- It has low-pressure losses and a high discharge coefficient.
- It can connected in a horizontal, inclined, or vertical direction.
- It has less chance of clogged.
- it has high pressure recovery and discharge pressure is about inlet pressure.

### Disadvantages of Venturi meter:

- It is used for small-sized pipes.
- It is larger so difficult to connect in small spaces.
- it has a limited range for fluid measurement.
- High cost than other flowmeters

**Read also:**