latter is energized opening the gas passage to a position in which the moving armature 5 comes into contact with the electromagnet 2 open valve position shown on the left side of fig1 and 6 when the electromagnet 2 is no longer energized the spring 6 acts on the plug 4 moving it together with the moving armature 5 to the closed valve position shown on the right side of fig1 and 6 closing the gas passage the electromagnet 2 comprises a core 9 supported in the seat 3 a reel 10 10 u2032 10 u2033 which is arranged such that it is inserted in the core 9 and a coil 11 which is arranged such that it is coiled on the reel 10 10 u2032 10 u2033 the core 9 may have a u shaped geometry defined by two arms attached through a base 9 c the reel 10 10 u2032 10 u2033 is arranged such that it is inserted in one of the arms of the core 9 the core 9 and moving armature 5 are made of ferromagnetic materials the support 3 is made of a preferably metallic electrically conductive material whereas the reel 10 10 u2032 10 u2033 is made of an electrically isolating material preferably plastic.