This part of ISO 23551 specifies safety, constructional and performance requirements and testing of automatic and semi-automatic shut-off valves for gas burners, gas appliances and appliances of similar use. It applies to — normally closed valves, — valves being mounted upstream to gas burners and gas appliances, — valves with declared maximum working pressures up to and including 500 kPa, for use on burners or in appliances using fuel gases as natural gas, manufactured gas or liquefied petroleum gas (LPG), — valves directly or indirectly actuated, electrically or by mechanical means, — valves actuated by hydraulic or pneumatic means, — valves where the flow rate is controlled by external electrical signals, either in discrete steps or propor­tional to the applied signal and — valves fitted with closed position indicator switches. This part of ISO 23551 covers type testing only.