This International Standard specifies requirements for the design, functional characteristics and manufacture of diaphragm valves made of thermoplastics materials intended for isolating and control service, their connection to the pipe system, the body materials and their pressure/temperature rating between − 40 °C and + 120 °C, for a lifetime of 25 years, and also specifies their tests. This International Standard is applicable to hand- or power-operated valves to be installed in industrial pipe systems, irrespective of the field of application and the fluids to be conveyed.