These flow meters are made from a thin plate, the orifice plate which has hole drilled into it. This plate is then inserted into a pipe or other section of the liquid flow system.
Once the fluid goes through the orifice it builds up pressure a bit before the orifice, it does this because the velocity of the flow is decreased as things must slow down in order to get through the smaller opening in the plate as opposed to freely flowing through the pipe.
Once the flow has passed through the hole in the orifice plate the pressure decreases as the velocity increases again. In order to find the rate of flow, these flow meters assess the difference between the fluid pressure that is upstream of the orifice plate and the fluid pressure that takes place downstream of the orifice plate.
As stated earlier, orifice plate flow meters are commonly found in piping systems that contain a single stream, well-mixed, continuous flowing liquid.
Because of this, the orifice plate flow meter can be used in a wide range of industries as long as the criteria are met within the application. Another use of these flow meters is to simply slow down the rate of flow or even restrict it, in these applications the orifice plate flow meter is often referred to as a restriction plate.
If you are interested in learning more about orifice plate flow meters, consult a trusted flow meter manufacturer and see if they can provide a solution for your application.