Irrigation valves control the quality, pressure and passage of water through your irrigation system.
A suction valve is to balance the pressure and avoid the loss of the volume of water from the siphon. When the discharge is finished, the valve closes, preventing bad odors from the installation from escaping to the outside.
The non-return valve allows the passage of water in only one direction, to work without fluid in the other or to avoid unwanted emptying. The force of the fluid causes the valve to open by forcing a disc and when the flow of the fluid stops, it would close again automatically.