In a known manually controlled valve of this type, the translation motion of the valve member is controlled by a control screw which passes through a tapped hole formed in the end face opposite to said first orifice and connected to the valve member by a circular "head" which is held in a T-shaped groove in the valve member, with the other end of the screw having a drive head. The valve body is made gastight by a metal bellows connecting the piston valve member to the end face of the valve through which said control screw passes.
Such a valve is driven relatively slowly since several complete turns of the screw are necessary to close the valve. In addition, such a valve is relatively expensive because of the metal bellows.
An object of the present invention is to mitigate these drawbacks and to provide a valve which is cheap and which can be driven quickly.