VANNE DONT L'OUVERTURE FONCTIONNE A LA DEPRESSION

VANNE DONT L'OUVERTURE FONCTIONNE A LA DEPRESSION, COMPRENANT UN CORPS CREUX 1 DIVISE EN UNE PREMIERE PARTIE 2 ET EN UNE SECONDE PARTIE 3 PAR UNE PAROI INTERNE 4, LA PREMIERE PARTIE ETANT MUNIE D'UNE PREMIERE OUVERTURE 5 DESTINEE A ETRE RELIEE A UNE ENCEINTE A VIDER, ET D'UNE SECONDE OUVERTURE 6 DESTINEE A ETRE RELIEE A L'ASPIRATION D'UNE POMPE A VIDE, UN CLAPET MOBILE 7, POUSSE PAR UN RESSORT 8 ET PERMETTANT D'OBTURER LADITE PREMIERE OUVERTURE, ETANT DISPOSE DANS LADITE PREMIERE PARTIE, LEDIT CLAPET COMPORTANT UNE QUEUE 10 TRAVERSANT LADITE PAROI INTERNE ET ETANT RELIEE A UN PISTON 11 SEPARANT LADITE SECONDE PARTIE EN DEUX CHAMBRES 13, 14, LEDIT PISTON ASSURANT L'ETANCHEITE ENTRE LES DEUX CHAMBRES DONT L'UNE 13, CELLE SITUEE DU COTE DE LADITE QUEUE ET APPELEE PREMIERE CHAMBRE, COMMUNIQUE AVEC L'EXTERIEUR, CARACTERISEE EN CE QUE L'AUTRE CHAMBRE 14, APPELEE SECONDE CHAMBRE, COMPORTE UN ORIFICE 22 DE COMMUNICATION AVEC L'EXTERIEUR MUNI DE MOYENS 23 D'OBTURATION ET EN CE QU'UNE COMMUNICATION 20 EST ETABLIE ENTRE LADITE PREMIERE PARTIE 2 DU CORPS ET LADITE SECONDE CHAMBRE 14.2.557.254 A valve which opens on reduced pressure comprises: a hollow body (1) divided into first and second portions (2 and 3) by an internal partition (4), with the first portion being provided with a first opening (5) for connection to an enclosure to be evacuated and with a second opening (6) for connection to the aspiration side of a vacuum pump; a moving valve plate (7) disposed inside the first portion; a spring (8) urging the valve plate to close the first opening; a rod (10) having one end connected to the valve plate and passing through the internal partition; and a piston (b 11) which is connected to the other end of the rod, and which divides the second portion into a first chamber (13) and a second chamber (14) which are sealed from each other, the first chamber being on the rod side of the piston and being in communication with the outside (19), and the second chamber including an orifice (22) for communication with the outside, which orifice is fitted with closure means (23), the second chamber further including means (20) putting the second chamber in communication with the first portion of the body.