Abstract: The invention relates to a quick-opening valve for a pressurized extinguishing fluid vessel, having an extinguishing fluid inlet (4), an extinguishing fluid outlet (5), a flow chamber which extends from the extinguishing fluid inlet (4) to the extinguishing fluid outlet (5), a valve piston (12), a valve seat (10), wherein the valve piston is movable back and forth between an opened-up position and a shut-off position such that the valve piston (12) and the valve seat (10), in the shut-off position, bear against one another in fluid-tight fashion and, in the opened-up position, are spaced apart from one another such that the extinguishing fluid inlet (4) and the extinguishing fluid outlet (5) are fluidically connected to one another. It is proposed according to the invention that the extinguishing fluid inlet (4) and the extinguishing fluid outlet (5) are oriented substantially parallel to one another.