# Test and Measurement World

## Test and Measurement World Terminology Section

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## Difference between Vortex flow meter and Turbine flow meter | Vortex flow meter vs Turbine flow meter

This page compares vortex flow meter vs turbine flow meter and mentions difference between vortex flow meter and turbine flow meter.

### Vortex flow meter

It works based on natural phenomenon which occurs when liquid flows around bluff object. In this meter, vortices are shed alternately down-stream of object, similar to flag flapping in breeze. More flag flaps when the wind blows faster. The "flapping" in liquid flows is known as "Shedding". The frequency of the shedding is directly proportional to velocity of liquid flowing through the Vortex flow meter. The more frequent "shedding" refers to high rate of flow of water.

It consists of two major components viz. flow tube and transmitter. The flow tube composed of three parts which include body, shedder and sensors.

Following are the features of Vortex flow meter:
• Pipe sizes: 2" to 20"
• Water to be used: clean to dirty
• Pressure loss: low to medium
• accuracy: +/-1% of full scale
• Length of straight pipe upstream of meter: 10 times of diameter
• Length of straight pipe downstream of meter: 5 times of diameter
• Cost: Low to medium

### Turbine flow meter

• They are devices or instruments in which small turbine wheel is placed in the pipe along the path of fluid flow. It is called volumetric flow meter.
• Flow of fluid causes rotation of blades of turbine. Each of these blades form magnetic circuit and produces voltage as per following equation.
|E| = b*m*Wr
Where,
m = number of blades
b = amplitude of angular variation in magnetic flux (in Wb)
Wr = angular velocity of wheel or turbine (in radians). frequency, f = (m*Wr)/(2*π)
• Generated output voltage has form of sine wave whose frequency is proportional to angular velocity of blade.
• Advantages: Good dynamic response, can measure totalized flow with higher accuracy