This part of ISO 13693 specifies the general requirements and test methods for small plastics-bodied valves used for chemigation, hereinafter referred to as the device , intended for operation in irrigation pipe systems which may contain fertilizers and chemicals of the type and concentration used in agriculture. It is applicable to controllable safety devices (also known as backflow preventers) with a reduced pressure zone (RPZ), intended to prevent backflow by back-siphonage or backpressure of irrigation water into an upstream potable water distribution system, whenever the pressure in the latter is lower than that in the system located downstream. It is applicable to such devices of nominal size up to and including DN 50 (2 ), with a nominal pressure of PN10, that are capable of working without modification or adjustment at any pressure up to 1 MPa (10 bar), with any pressure variation up to 1 MPa (10 bar), and in permanent duty at temperatures up to 45 °C and for 1 h at 65 °C.