Full-drain type vacuum breaker

A vacuum breaker comprising:

• a safe valve body, an elastic gasket, a water outlet washer, an elastic sealing gasket, a water outlet seat, a elastic member and a push member;
• wherein:
• the safe valve body includes an upper section, an intermediate section and a lower section;
• the lower section of the safe valve body is provided with a lower internal thread for locking the water outlet seat, a first stepped edge for receiving the water outlet washer, and a second stepped edge for receiving the elastic sealing gasket;
• the push member is received in the water outlet seat and abuts the elastic sealing gasket;
• the elastic member is received in the water outlet seat and is biased between the push member and the water outlet seat;
• the elastic sealing gasket is pushed by the push member and abuts the water outlet washer;
• the safe valve body has a center provided with a passage;
• the passage of the safe valve body is provided with a conical face;
• the intermediate section of the safe valve body has an interior provided with a receiving space;
• the receiving space of the safe valve body is provided with a stop edge protruding inward;
• the elastic gasket is received in the receiving space of the safe valve body;
• the receiving space of the safe valve body has an outer periphery provided with a plurality of connecting holes to allow discharge of air and fluid during a vacuum breaking process;
• the elastic gasket has a size smaller than that of a circumferential wall of the receiving space of the safe valve body, with clearances being defined between the elastic gasket and the circumferential wall of the receiving space of the safe valve body;
• the elastic gasket has a center provided with a through hole and has an outer periphery provided with a sealing portion extending upward;
• the sealing portion of the elastic gasket has a bottom provided with a thicker portion and a top provided with a thinner portion so that the sealing portion of the elastic gasket has an elastic force and is capable of expanding outward and contracting inward;
• the sealing portion of the elastic gasket contracts inward when water stops passing the safe valve body, so that ambient air flows into the receiving space of the safe valve body to break a vacuum state in the safe valve body, such that a fluid contained in the safe valve body flows through the clearances between the elastic gasket and the safe valve body, and is drained outward from the connecting holes of the safe valve body;
• and
• when the water passes the safe valve body, an air pressure in the safe valve body presses down the elastic gasket and the sealing portion, so that the sealing portion of the elastic gasket expands outward to seal the connecting holes of the safe valve body, thereby preventing the fluid from passing through and leaking from the connecting holes of the safe valve body, and thereby preventing the ambient air from entering the safe valve body.