An electric valve comprising: a valve body, the valve body housing: a nut having a central shaft; a screw threadingly engaged within said nut, the screw having a screw axis; at least one projection attached at a periphery of said nut; and a limiter positioned in an inner side of said valve body and configured so that said at least one projection is abuttable therewith; wherein said nut moves together with said screw until said at least one projection reaches and abuts against said limiter; characterized in that the valve further comprises: a seal mounted to said central shaft and configured to move freely with respect to the central shaft, both axially and rotatably there-about; sliding bearings disposed between said nut and said seal and disposed between said nut and a base of said screw; and a lip correspondingly disposed with respect to said seal and reversibly engagable therewith; whereby, due to the slide bearings, neither upon opening of the valve nor upon closing of the valve does the seal slide on the lip. a valve body, the valve body housing: a nut having a central shaft; a screw threadingly engaged within said nut, the screw having a screw axis; at least one projection attached at a periphery of said nut; and a limiter positioned in an inner side of said valve body and configured so that said at least one projection is abuttable therewith; wherein said nut moves together with said screw until said at least one projection reaches and abuts against said limiter; characterized in that the valve further comprises: a seal mounted to said central shaft and configured to move freely with respect to the central shaft, both axially and rotatably there-about; sliding bearings disposed between said nut and said seal and disposed between said nut and a base of said screw; and a lip correspondingly disposed with respect to said seal and reversibly engagable therewith; whereby, due to the slide bearings, neither upon opening of the valve nor upon closing of the valve does the seal slide on the lip. a nut having a central shaft; a screw threadingly engaged within said nut, the screw having a screw axis; at least one projection attached at a periphery of said nut; and a limiter positioned in an inner side of said valve body and configured so that said at least one projection is abuttable therewith; wherein said nut moves together with said screw until said at least one projection reaches and abuts against said limiter; characterized in that the valve further comprises: a seal mounted to said central shaft and configured to move freely with respect to the central shaft, both axially and rotatably there-about; sliding bearings disposed between said nut and said seal and disposed between said nut and a base of said screw; and a lip correspondingly disposed with respect to said seal and reversibly engagable therewith; whereby, due to the slide bearings, neither upon opening of the valve nor upon closing of the valve does the seal slide on the lip. a seal mounted to said central shaft and configured to move freely with respect to the central shaft, both axially and rotatably there-about; sliding bearings disposed between said nut and said seal and disposed between said nut and a base of said screw; and a lip correspondingly disposed with respect to said seal and reversibly engagable therewith; whereby, due to the slide bearings, neither upon opening of the valve nor upon closing of the valve does the seal slide on the lip.