It is applicable to hydraulically-operated control irrigation valves of DN 15 (1/2 inch) diameter or greater, designed to operate in any position, from fully open to fully closed. The valves can either be directly operated (i.e. the force applied via a spring or diaphragm to the obturator), or pilot-operated (i.e. the force is applied through an adjustable pilot valve via a diaphragm). These valves can also function as check valves.