This part of ISO 23553 specifies safety, constructional and performance requirements, and testing of safety shut-off devices, for liquid fuels. This part of ISO 23553 covers type testing only. It applies to safety shut-off devices which:- are designed as e.g. automatic valves or fast-closing devices; - are used in combustion plants to interrupt the flow of liquid fuels with or without delay on closing and with or without delay on opening; - are for use with fuel oils; NOTE For other liquid fuels, additional test methods can be agreed between the manufacturer and the test authority. - form part of a device having other function(s), such as oil pumps. In this case the test methods apply to those parts or components of the device forming the safety shut-off device, i.e. those parts which are necessary for the closing function; - have declared maximum working pressures up to and including 5 000 kPa, for use on burners or in appliances using liquid fuels; - are directly or indirectly operated electrically or by mechanical or hydraulic means; - are fitted with or without closed-position indicator switches. The methods of test given in this part of ISO 23553 are intended for product type testing.