Ventil

摘要

A first valve portion (5) and a second valve portion (6) are arranged in series in a flow passage (4) within a valve casing (1) to open and close the flow passage (4). The first valve portion (5) includes a first valve seat (8), a first valve element (10) supported to a first valve shaft (9) and adapted to make an axial reciprocating movement into contact with or away from the first valve seat (8), and an opening and closing drive unit (13) composed of a motor (11) and a motion converting mechanism (12) that converts a rotary motion into a linear motion, the opening and closing drive unit (13) causing the first valve shaft (9) to make a reciprocating movement and capable of effecting a flow rate control and slow valve-opening for the flow passage (4). The second valve portion (6) includes a second valve seat (15), a second valve element (16) adapted to move into contact with or away from the second valve seat (15), a compression spring (17) that urges the second valve element (16) into contact with the second valve seat (15), and an electromagnetic valve-opening unit (18) for moving the second valve element (16) away from the second valveseat (15) byanelectromagnetic force and capable of effecting quick valve-closure for the flow passage (4). Therefore, upon valve opening, the valve portion can be opened gradually to a set flow rate, and when a need arises to effect emergency val ve closure or upon power outage, the valve portion can be closed instantaneously, whereby it is possible to prevent occurrence of a defect or the like in equipment using a fluid and ensure safety.