Which type of orifice plate is described as having a round opening?

A concentric orifice plate is characterized by its round opening, which allows for a uniform flow of fluid through the opening. This design is beneficial for achieving stable flow characteristics and is commonly used in applications where accurate measurement and control of fluid flow are essential. The round shape of the orifice also minimizes turbulence and ensures that the flow remains streamlined, leading to better meter accuracy.

Choosing a concentric orifice is often preferred in various industrial applications, as it is effective in both high and low-pressure systems. The design helps in preventing any interference with the flow stream, making it reliable for measuring the flow rate of liquids and gases.

The other types of orifice plates mentioned have different configurations that may not feature a round opening or are designed for specific types of flow measurement or processes, thus distinguishing them from the concentric type.