Abstract: Pressure capsule for spray can, characterized by the fact that it principally consists of at least two chambers (2, 3), the first of which (2) is intended to be filled with fluid under relatively high pressure and the second of which (3) is intended to be filled with a fluid up to a pressure equal or practically equal to the overpressure which normally exists in a spray can (19) and which is needed for expelling a liquid (18); in the wall of the second chamber (3), a membrane (5) that can control the valve (4); and a removable element (6) that, in its unremoved condition, keeps the valve (4) closed.