Orifice plate: a thin plate with a hole drilled into it, inserted into a pipe or another section of a liquid flow system
Orifice plates can have sharp leading edges with a short cylindrical section, a fully rounded leading edge with no cylindrical section, or a beveled leading edge with a very short cylindrical section. Respectively, these orifice plate types are known as: sharp edged thin plates, quarter-circle or quadrant-edge orifices, and conical inlet or conical entrance plates.
As fluid pours into the orifice, flow pressure increases, and flow velocity decreases. This happens because flow rate has to slow down and constrict in order to fit through such a small opening. Once the flow has passed through the hole, flow pressure decreases and flow velocity increases again. To find flow rate and velocity, these meters use the same principles as venturi flow meters. That is to say, they use the relationship between the velocity of a liquid and the pressure of the liquid to determine the actual velocity of the flow of liquid. For example, if the pressure of the liquid decreases, then you know that the velocity of the flow has increased. They also determine flow rates by measuring the difference between the pressure of the upstream fluid and pressure of the downstream fluid.
Orifice plate flow meters are ideal for piping systems that contain a well-mixed, continuously flowing single stream liquid. They can also be used to slow or restrict flow. When used for the slowing or restricting of flow, they can alternatively be referred to as “restriction plates.” One of the most common applications of orifice plate flow meters is the measure of natural gas. They are also frequently used to measure low viscosity liquids. They can be found in the petrochemical, aviation, automotive, medical, chemical, and water treatment industries, among others.
If you are interested in learning more about orifice plate flow meters, consult a reputable flowmeter manufacturer and see if they can provide a solution for your application. Make sure to talk to them about any industry or governmental standards to which your flow meters must adhere.