The invention relates to a valve unit for a pressure vessel, the latter consisting of a receptacle and a lid which can be placed on said receptacle in such a way as to make it pressure-tight and said valve unit including: a safety function, pressure-relief function and pressure indicator function; adjustable indicator levels and pressure levels; an indicator pin (4) or indicator piston (10) which is supported against an indicator spring (7), can move in axial direction and bears on its portion becoming visible upon pressurization, due to its emergence from a valve housing (12), indicator rings, for example, for indicating the pressure inside the vessel; and comprising a valve body (5) which is movable in axial direction against the action of an exhaust steam spring (6) and, in the closed position, rests against a seal seat (19), lifting off from this, when a given pressure inside the vessel is exceeded, to uncover a pressure-relief aperture (20), in which case both the indicator spring (7) and the exhaust steam spring (6) are braced in the same direction against a common, axially adjustable pressure member (8).