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 0.6. beta ratio means ratio of the orifice bore to the internal pipe diameters.

(45º beveled edges are often used to minimize friction resistance to flowing fluid )