A circuit breaker, comprising: first and second electrical contacts (142, 144), the electrical contacts (142, 144) configured to generate an electrical arc upon being separated during operation of the circuit breaker; a first chamber at least partially surrounding the first and second electric contacts (142, 144); a second chamber filled with insulating gas; and a valve assembly configured to allow threshold-based flow of the insulating gas into and out of the first chamber, the valve assembly comprising: a valve body interconnecting the first chamber and the second chamber; a first valve plate movably mounted in the valve body; and a second valve plate arranged in the valve body so as to move between a first position, a second position and a third position therein, wherein in the first position, the second valve plate is seated on the first valve plate, in the second position, the second valve plate is lifted from the first valve plate to above the first position thereof, and in the third position, the second valve plate is seated on the first valve plate and moves the first valve plate therewith below the first position thereof, characterized in that the valve assembly comprises a plurality of Belleville springs radially arranged in the valve body below the first valve plate, the plurality of Belleville springs configured to constrain the movement of the first valve plate up to the third position of the second valve plate in the valve body, and wherein the valve body comprises a stopper formed therein, such that the stopper limits the lifting of the second valve plate up to the second position thereof in the valve body. first and second electrical contacts (142, 144), the electrical contacts (142, 144) configured to generate an electrical arc upon being separated during operation of the circuit breaker; a first chamber at least partially surrounding the first and second electric contacts (142, 144); a second chamber filled with insulating gas; and a valve assembly configured to allow threshold-based flow of the insulating gas into and out of the first chamber, the valve assembly comprising: a valve body interconnecting the first chamber and the second chamber; a first valve plate movably mounted in the valve body; and a second valve plate arranged in the valve body so as to move between a first position, a second position and a third position therein, wherein in the first position, the second valve plate is seated on the first valve plate, in the second position, the second valve plate is lifted from the first valve plate to above the first position thereof, and in the third position, the second valve plate is seated on the first valve plate and moves the first valve plate therewith below the first position thereof, characterized in that the valve assembly comprises a plurality of Belleville springs radially arranged in the valve body below the first valve plate, the plurality of Belleville springs configured to constrain the movement of the first valve plate up to the third position of the second valve plate in the valve body, and wherein the valve body comprises a stopper formed therein, such that the stopper limits the lifting of the second valve plate up to the second position thereof in the valve body. a valve body interconnecting the first chamber and the second chamber; a first valve plate movably mounted in the valve body; and a second valve plate arranged in the valve body so as to move between a first position, a second position and a third position therein, wherein in the first position, the second valve plate is seated on the first valve plate, in the second position, the second valve plate is lifted from the first valve plate to above the first position thereof, and in the third position, the second valve plate is seated on the first valve plate and moves the first valve plate therewith below the first position thereof, characterized in that the valve assembly comprises a plurality of Belleville springs radially arranged in the valve body below the first valve plate, the plurality of Belleville springs configured to constrain the movement of the first valve plate up to the third position of the second valve plate in the valve body, and wherein the valve body comprises a stopper formed therein, such that the stopper limits the lifting of the second valve plate up to the second position thereof in the valve body.