Advantages and disadvantages of orifice meter and venturi meter
Orifice meter
Main article: Orifice plate
An orifice meter or orifice plate is a flat plate having a central hole that is placed across the flow of a liquid, usually between flanges in a pipeline. The pressure difference generated by the flow velocity through the hole enables the flow quantity to be measured.[1]
Venturi meter
A venturi meter is a flow measurement instrument which use a converging section of pipe to give an increase in the flow velocity and a corresponding pressure drop from which the flow rate can be deduced. They have been in common use for many years, especially in the water supply industry[2]
Advantages and Disadvantages of Orifice meter and Venturimeter
Advantages of orifice meter
- Orifices are small plates and easy to install/remove.
- Offer very little pressure drop of which 60% to 65% is recovered.
- Orifice meter can be easily maintained.
- Measures a wide range of flow rates.
- They have a simple construction.
- They have easily fitted between flanges.
- They are most suitable for most gases and liquids.
- They are inexpensive.
- Price does not increase dramatically with size.
Disadvantages of orifice meter
- Requires homogeneous fluid.
- Requires single phase liquid.
- Requires axial velocity vector flow.
- Causes a pressure drop in fluid.
- Their accuracy is affected by density,pressure and viscosity fluid.
- Fluid viscosity limits measuring range.
- Requires straight pipe runs to ensure accuracy is maintained.
- Pipe line must be fully especially for liquid flow measurement.
- They have low range-ability.
Advantages of venturi meter
- Less chances of getting clogged with sediments.
- co-efficient of discharge is high.
- Its behaviour can be predicted perfectly.
- Can be installed vertically,horizontally,inclined.
- They are more accurate and can be used for a wide range of flows.
- Around 90% of pressure drop can be recovered.
Disadvantages of venturi meter
- They are large in size and hence where space is limited,they cannot be used.
- Expensive initial cost,installation and maintenance.
- Require long laying length.That is,the venturimeter has to be proceeded by a straight pipe which is free from fittings and misalignment's to avoid turbulence in flow, for satisfactory operation.
- Cannot be used in pipes below 7.5 cm diameter.
- Maintenance is not easy.
- Cannot be altered for measuring pressure beyond a maximum velocity.
References
- ↑ http://www.dictionary.com/browse/orifice-meter
- ↑ http://www.thermopedia.com/content/1241
- 1 2 3 4 RK RAJPUT (2010). a textbook of fluid mechanics
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