The invention relates to an injection pressurizer for pressurizing an inflatable device comprising:—a housing enclosing a first cavity—a plunger adapted to fit inside said housing and provided with a plunger sealing unit adapted to define a second cavity inside said housing, the plunger is further provided with an end part at the end opposite the plunger sealing unit wherein the plunger further comprisesan elongated tube defining a tube cavity extending from said plunger sealing unit to said end part of the plunger, said tube cavity being in fluid communication with said second cavity via an opening in said plunger sealing unit and a pressure indicating piston adapted to be moveably arranged inside said tube cavity, such that the piston delimits a first volume (A) in said tube cavity from a second volume (B), such that when a pressure is built up in the second volume (B), the piston is moved by the pressure to equalize the pressures of said first volume (A) and said second volume (B), and thereby indicates the pressure in the second volume (B). The invention relates according to another aspect to a method of pressurizing an inflatable device with an injection pressurizer.
