What is concentric orifice plate?

The concentric orifice plate is used for ideal liquid as well as gases and steam service. This orifice plate beta ratio fall between of 0.15 to 0.75 for liquids and 0.20 to 0.70 for gases, and steam. Best results occur between value of 0.4 and 06. Beta ratio refers to the ratio of the orifice bore to the internal pipe diameters

What is  concentric orifice plate

( 45 Deg beveled edges are often used to minimize Friction resistance to flowing fluid)