ISO 23555-3 specifies safety, constructional, performance, testing and documentation requirements of gas safety shut-off devices (hereafter referred to as `SSD`). ISO 23555-3 is applicable to SSDs with operating pressures greater than 500 kPa (5 bar) up to 10 MPa (100 bar) of nominal connection sizes up to and including DN 400 for use with fuel gases as natural gas, manufactured gas, biomethane or liquefied petroleum gas (LPG) in commercial, industrial installations, including fuel gas infrastructures. ISO 23555-3 is applicable to SSDs for an operating temperature range from –20 °C to +60 °C; ISO 23555-3 is applicable to: - test methods which are intended for product type test, routine tests and batch surveillance tests; - SSDs which use the pipeline gas as a source of control energy unassisted by any external power source; - SSDs integrating on the same body a second SSD, complying with the requirements in this document; - SSDs integrating a regulator complying with ISO 23555-2. - SSDs incorporating a creep (venting) relief device and/or a vent limiter complying with the requirements in this document; ISO 23555-3 does not apply to: - SSDs upstream from/on/in domestic gas-consuming appliances which are installed downstream of domestic gas meters; - SSDs designed to be incorporated into pressure control systems used in service lines (pipework from the main pipework in a gas infrastructure to the point of delivery of the gas) with declared volumetric flow rate ≤ 200 m3/h (n) and declared inlet pressure ≤ 500 kPa (5 bar); - industrial process control valves on/off type (ref. IEC 60534); - SSDs used in aggressive/sour gas environments (gas environments containing water and H2S are considered sour) or severely corrosive conditions. - SSDs in service conditions with renewables (e.g. H2NG with hydrogen more than 10 %) and/or waste gases (e.g. biogas etc.), if additional information is not provided (e. g. contaminant, liquid etc.).