Orifice and venturi meter:
Orifice and venturi meter works under the same principle, both meters creates a restriction in the flow channel and the pressure difference across the restriction is measured, which is proportional to the rate of discharge of flowing fluid through the pipeline.
Advantages and disadvantages of Orifice and venturi meter are listed below:
Advantages of Orifice meter:
- The Orifice is small plates and easy to install/remove.
- Offer very little pressure drop from which 60% to 65% is recovered.
- The orifice meter can be easily maintained.
- Measures a wide range of flows.
- They have a simple construction.
- They have easily fitted between the flanges.
- They are the most suitable for most gases and liquids.
- They are cheap, The price does not increase dramatically with size.
Disadvantages of orifice meter:
- Requires homogeneous fluid.
- Requires single phase liquid
- It requires the flow of axial velocity vectors.
- It causes a pressure drop in the fluid.
- Its accuracy is affected by the density, pressure and viscosity of the fluid.
- The range of measurement of viscosity limits of fluids.
- It requires straight conduits to ensure accuracy is maintained.
- The pipe must be totally special for the measurement of the flow of liquids.
- They have low range capacity.
Advantages of venturi meter:
- Less chance of getting stuck with sediment.
- The discharge coefficient is high.
- Its behaviour can be predicted perfectly.
- It can be installed vertically, horizontally, inclined.
- They are more precise and can be used for a wide range of flows.
- About 90% of the pressure drop can be recovered.
Disadvantages of venturi meter:
- They are large in size and, therefore, where space is limited, they can not be used.
- Initial costs, installation and expensive maintenance.
- Requires a long placement length. That is, the venturi meter must be driven by a straight tube that has no connections or misalignments to avoid turbulence in the flow, for satisfactory operation.
- It can not be used in pipes of less than 7.5 cm in diameter.
- Maintenance is not easy.
- It can not be modified to measure the pressure beyond a maximum speed