Orifice plates with angular holes are specific types of throttling devices used for indirect measurement of air flow mass. This specific type of orifice plates is used especially in air-conditioning or in industrial applications with rectangular or square sections of the conduits.

A hole in the plate can be of square or rectangular profile and it is used to generate pressure differential of the static pressure upstream and downstream the plate. The calculation is based on mathematical similarity of equivalent sections. The pressure differential is transmitted through tappings or pressure differential outlets to the measuring devices such as U-tubes with water or mercury content or, nowadays more used sensors transferring the pressure difference to electronic signal and after entering required technical parameters toy calculate measured air flow mass directly.

The main advantage of the angular hole orifice plate is, that it adapts to angular air conduits without necessity to insert passes to the oval piping at the point of measurement. Its significant advantage is its construction simplicity, as it is the case of centric orifice plates.

Orifice plate with angular holes is manufactured as the verified (approved) meter. Square and rectangular orifice plates can be inserted both in vertical and in horizontal pipelines.