Venturi Meter: The Best Device to Measure Fluid Flow
Venturi meters are used to determine the flow rate of various fluids by measuring the change in pressure as the fluids pass through it. Venturi meters are widely used due to low permanent pressure loss and also because these are more accurate as compared to other measuring devices such as orifice plates or flow nozzles.
A venturi meter is a short pipe that consists of two conical parts with a short portion of uniform cross section in between. The aforesaid two conical parts have the same base diameter, with one part having a shorter length and a larger cone angle whereas the other part has a smaller cone angle with a larger length.
Although venturi meters are available in various sizes, yet these usually have a uniform flow coefficient (relative measure of it's efficiency at allowing fluid flow) value of 0.984 irrespective of size. Venturi meters can be manufactured so as to fit any requisite pipe size. The temperature and pressure within the pipe does not affect the accuracy of the venturi meter.
Working of a Venturi Meter:
The venturi meter is always used in a way so as to make sure the upstream part of the flow takes place through the short conical portion while the downstream part flows through the long conical portion.
The above process ensures a rapid converging passage and a gradual diverging passage in the flow direction to eliminate any chance of energy loss due to separation.
Subsequently, the velocity of the fluid reaches it's maximum value and pressure reaches it's minimum value while it flows through the divergent part.
Flow rate of the fluid is determined by assessing the typical variation in velocity and pressure.
Benefits of Using Venturi Meters
Long known for their durability, affordability and reliability, venturi meters provide benefits that are unmatched by any other flow measuring device. Some of the benefits are:
Venturi meters provide the widest variety of measurement options in piped systems. Although majorly used for fluid measurement, these are also used for gas, steam or any mixed material flow measurement.
The laying length of venturi meters can be customized to fit a particular space.
These can also be used for billing, custody transfer as well as for rectangular or circular metering.
These can further be customized for a much better tolerance to upstream conditions and asymmetric flow patterns.