Abstract: A flow control valve comprising a main valve for opening and closing a fluid conduit, an electromagnetic coil for driving the main valve, a diaphragm responsive to the action of the main valve, a sub-valve chamber partitioned by the main valve and the diaphragm, a sub-valve incorporated in the main valve for opening and closing the sub-valve chamber to a conduit in the secondary side, a projection, protrusively formed on a driving shaft of the electromagnetic coil, responsive to a driving force of the electromagnetic coil for sliding the sub-valve by a predetermined stroke to bring the same in a fully opened state with the main valve remaining in a closed state and thereafter opening the main valve, a bleed orifice provided through a side wall of the main valve for making the pressure in the sub-valve chamber equal to a primary pressure; and a returning spring for urging each of the main valve and the sub-valve in the closing direction.

Abstract: A safety shut-off valve opening a flow path between the primary and secondary sides in case of usual operation, while shutting off the aforesaid path in response to an emergency shut-off signal, and particularly such safety shut-off valve cannot be reset unitl it is confirmed that there is no more leakage of gas on the secondary side of the shut-off valve after the shut-off action was once effected, thereby to attaining a very high safeness.

Abstract: An electromagnetic actuator utilizing a fluid pressure obtained from an electromagnetic pump, wherein according to the present invention, there is provided a responsive member displaceable in response to the pressure of a fluid forced into a second chamber from a first chamber. The responsive member displaceable as described can operate a valve member or the like coupled thereto in an on-off control or a proportional control with a large stroke in a reliable manner.