Venting and degasifying valve for a liquid-filled system

A venting and degasifying valve, for a liquid-filled system, comprising a stopper for screwing into an opening in the system and which is subdivided, by a partition provided with a central valve opening, into an inner chamber and an outer chamber, a valve ball disposed in the inner chamber and forced by a compression spring into the valve opening, a closure screw engaged an internal thread in the outer chamber and having a stem on which are disposed stopping rings which swell when subjected to moisture, venting openings leading outwards from the outer chamber in register with the stopping rings and a pusher formed as an extension of the stem and disposed, in the screwed-in position of the closure screw, to project through the valve opening and into the inner chamber for lifting the valve ball, characterised in that, in the closure screw, in the stem, and possibly in the pusher, there is a venting channel displaceably accommodating, with a clearance, a spindle which protrudes at the end, remote from the valve ball, of the closure screw and on the inner end of which at least a portion of the pusher is so fastened that a closure surface, formed on a reverse end of said portion, can be lifted from the venting channel end by means of the spindle.