Orifice Plate Flowmeter
An orifice plate flowmeter is a device used in measuring the speed of fluid flow. It uses exactly the same principle like a Venturi nozzle, namely Bernoulli's principle which states that you've a relationship between pressure in the fluid and also the velocity on the fluid. If your velocity increases, pressure decreases and the other way round.
An orifice plate flowmeter is actually a thin plate using a hole in the centre. It will always be used in a pipe where fluid flows. Once the fluid reaches the orifice plate flowmeter, using the hole in the centre, the fluid is forced to converge to undergo the small hole; the stage that maximum convergence actually occurs shortly downstream of the physical orifice, along at the so-called vena contracta point (see drawing right). Mainly because it does so, the rate along with the pressure changes. After dark vena contracta, the fluid expands as well as velocity and pressure change all over again. By measuring the real difference in fluid pressure between your normal pipe section possibly at the vena contracta, the volumetric and mass flow rates can be acquired from Bernoulli's equation.
Orifice plate flowmeter are most commonly used by continuous measurement of fluid in pipes. They are also utilised in some small river systems to measure flow at locations where the river passes by using a culvert or drain. Only one few rivers are appropriate for any using the technology considering that the plate must remain completely immersed i.e the approach pipe has to be full, and also the river has to be substantially free of debris.
From the environment large orifice plate flowmeter are employed to control onward flow in flood relief dams. in these structures a minimal dam is defined across a river and normal operation the river flows in the orifice plate flowmeter unimpeded because orifice is substantially bigger than the traditional flow cross section. However, in floods, the flow rate rises and floods out of orifice plate flowmeter which will then only pass a flow determined by the physical dimensions from the orifice. Flow will be held back behind over the dam in a very temporary reservoir which can be slowly discharged through the orifice if your flood subsides.
