Abstract: An overflow preventing valve apparatus comprises a valve main body provided at a terminal end of a fluid supplying system passage, a main valve fixed to a separating membrane stretched within the valve main body to separate an upper chamber and a lower chamber, when the main valve is displaced upwards and downwards accompanied by deformation of the separating membrane and closing a fluid supplying passage upon moving downwards, a pilot valve for opening and closing the main valve in response to the opening and closing of the pilot valve itself, where the pilot valve is opened by a fluid supply starting operation, a lock mechanism for locking the pilot valve in an open state, a first lock releasing mechanism responsive to the detection of a dangerous fluid level which could lead to an overflow, for releasing the locking operation by the lock mechanism to close the pilot valve, and a second lock releasing mechanism responsive to the closing operation of the main valve at the time when the supply of fluid is sto

Abstract: An actuator for operating a driven device in an emergency comprises: an actuator mechanism having a cylinder, a piston slidably disposed within the cylinder and coupled to the driven device, an operational chamber defined by the cylinder and piston, and a passage communicating with the operational chamber; a high pressure gas generating source comprising a container vessel having an opening, a high pressure gas generating medium contained within the vessel, and a sealing member for sealing the opening of the vessel; and unsealing means operating in response to an emergency operation signal from the outside to unseal the sealing member of the high pressure gas generating source. High pressure gas from the high pressure gas generating medium flows through the opening and passage into the operational chamber upon unsealing of the sealing member of the high pressure gas generating source and operates the piston thereby to drive the driven device.