Abstract: A flow control valve is provided in a manner to be capable of locking a position of a differential screw easily without displacing a position adjusted valve element body. The valve element body is brought into or out of contact with a valve seat provided between a first port and a second port, and is connected to an operation member. The operation member is movably inserted into a cover and urged to a direction toward the valve seat by an urging member. A position of the operation member is adjusted by a differential screw, and accordingly a position of the valve seat is adjusted. A rotation member for exerting a rotation force on the differential screw is slidably mounted in the cover along a moving direction of the operation member without rotating. A locking portion is provided in the rotation member to engage with the cover without rotating when the operation member is slid along its moving direction.

Abstract: A flow control valve is provided in a manner to be capable of locking a position of a differential screw easily without displacing a position adjusted valve element body. The valve element body is brought into or out of contact with a valve seat provided between a first port and a second port, and is connected to an operation member. The operation member is movably inserted into a cover and urged to a direction toward the valve seat by an urging member. A position of the operation member is adjusted by a differential screw, and accordingly a position of the valve seat is adjusted. A rotation member for exerting a rotation force on the differential screw is slidably mounted in the cover along a moving direction of the operation member without rotating. A locking portion is provided in the rotation member to engage with the cover without rotating when the operation member is slid along its moving direction.

Abstract: A chemical liquid valve is arranged such that a diaphragm coupled to a piston rod is brought into/out of contact with a valve seat provided between an inlet port and an outlet port. To achieve a chemical liquid valve providing stable sealing strength, the diaphragm includes an engagement part whose top end is formed in semispherical shape, which is inserted and engaged in a recess of the piston rod so that the engagement part of the diaphragm comes into point contact with an inner wall of the recess of the piston rod. Thus, the piston rod swingably holds the diaphragm.

Abstract: A chemical liquid control valve is provided with a barrier on an outer circumferential end portion of a protruding part (an outer circumferential bottom portion of a valve seat). The barrier is placed so that an angle between the center line of an outlet passage and the line extending between the center of a valve port and each end of the barrier. The barrier is designed to have a height relative to a contact surface of the valve seat with a valve element is substantially half of the travel distance of a diaphragm valve element.

Abstract: A chemical liquid control valve is provided with a barrier on an outer circumferential end portion of a protruding part (an outer circumferential bottom portion of a valve seat). The barrier is placed so that an angle between the center line of an outlet passage and the line extending between the center of a valve port and each end of the barrier. The barrier is designed to have a height relative to a contact surface of the valve seat with a valve element is substantially half of the travel distance of a diaphragm valve element.

Abstract: A chemical liquid valve is arranged such that a diaphragm coupled to a piston rod is brought into/out of contact with a valve seat provided between an inlet port and an outlet port. To achieve a chemical liquid valve providing stable sealing strength, the diaphragm includes an engagement part whose top end is formed in semispherical shape, which is inserted and engaged in a recess of the piston rod so that the engagement part of the diaphragm comes into point contact with an inner wall of the recess of the piston rod. Thus, the piston rod swingably holds the diaphragm.

Abstract: A diaphragm valve capable of increasing durability of a diaphragm comprises a valve body internally formed with a valve chamber having an open upper end and a suck-back chamber having an open lower end, between an inlet passage and an outlet passage, and a through hole which provides communication between the valve chamber and the suck-back chamber. The open end of the valve chamber is closed by a first diaphragm which is brought into and out of contact with a valve seat. The open end of the suck-back chamber is closed by a second diaphragm. The first and second diaphragms are substantially identical in shape. Each circumferential edge portion of the first and second diaphragms is tightly retained by a retaining member mountable to the valve body so that the diaphragms are curved outwardly with respect to the valve chamber and the suck-back chamber respectively.

Abstract: A diaphragm valve capable of increasing durability of a diaphragm comprises a valve body internally formed with a valve chamber having an open upper end and a suck-back chamber having an open lower end, between an inlet passage and an outlet passage, and a through hole which provides communication between the valve chamber and the suck-back chamber. The open end of the valve chamber is closed by a first diaphragm which is brought into and out of contact with a valve seat. The open end of the suck-back chamber is closed by a second diaphragm. The first and second diaphragms are substantially identical in shape. Each circumferential edge portion of the first and second diaphragms is tightly retained by a retaining member mountable to the valve body so that the diaphragms are curved outwardly with respect to the valve chamber and the suck-back chamber respectively.