This document specifies constructional, functional, testing and marking requirements, sizing and documentation of gas safety shut-off devices used in the pressure regulating stations in accordance with EN 12186 or EN 12279:- for inlet pressures up to 100 bar and nominal diameters up to DN 400;- for an operating temperature range from -20 °C to +60 °C,which operate with fuel gases of the 1st and 2nd family in accordance with EN 437 in transmission and distribution networks and also in commercial and industrial installations.""""Gas safety shut-off devices"""" will hereafter be called """"SSDs"""" except in titles.For standard safety shut-off devices when use