Assembly, suitable for dispensing a product by means of a pressurized gas, comprising: - a) a high-pressure gas cartridge; - b) a pressure-reducing unit comprising: -- a high-pressure gas inlet to which the high-pressure gas cartridge is detachably connected; -- a low-pressure gas outlet in which is arranged a supply valve which is normally closed and which comprises a supply control rod which controls the opening of the supply valve; -- a bleed duct in which is arranged a bleed valve which is normally closed and which comprises a bleed control rod which controls the opening of the bleed valve to allow the gas to flow from an upstream end to a downstream end of the bleed duct; - c) and a cap: -- which is removably secured to the pressure-reducing unit with which it delimits an internal utilization chamber which is supplied with low-pressure gas via said outlet of the pressure-reducing unit and which is connected to the upstream end of said bleed duct; -- which is rotatable relative to the pressure-reducing unit between: i) a first angular end position for installing the cap on or removing it from the pressure-reducing unit; ii) and a second angular end position for securing the cap to the pressure-reducing unit, characterized in that the cap which comprises a cam which engages with the supply control rod and/or with the bleed control rod to sequentially causes opening and/or closing of the supply valve and/or the bleed valve on the basis of the angular position of the cap relative to the pressure-reducing unit between its first angular end position and its second angular end position. - a) a high-pressure gas cartridge; - b) a pressure-reducing unit comprising: -- a high-pressure gas inlet to which the high-pressure gas cartridge is detachably connected; -- a low-pressure gas outlet in which is arranged a supply valve which is normally closed and which comprises a supply control rod which controls the opening of the supply valve; -- a bleed duct in which is arranged a bleed valve which is normally closed and which comprises a bleed control rod which controls the opening of the bleed valve to allow the gas to flow from an upstream end to a downstream end of the bleed duct; -- a high-pressure gas inlet to which the high-pressure gas cartridge is detachably connected; -- a low-pressure gas outlet in which is arranged a supply valve which is normally closed and which comprises a supply control rod which controls the opening of the supply valve; -- a bleed duct in which is arranged a bleed valve which is normally closed and which comprises a bleed control rod which controls the opening of the bleed valve to allow the gas to flow from an upstream end to a downstream end of the bleed duct; - c) and a cap: -- which is removably secured to the pressure-reducing unit with which it delimits an internal utilization chamber which is supplied with low-pressure gas via said outlet of the pressure-reducing unit and which is connected to the upstream end of said bleed duct; -- which is rotatable relative to the pressure-reducing unit between: i) a first angular end position for installing the cap on or removing it from the pressure-reducing unit; ii) and a second angular end position for securing the cap to the pressure-reducing unit, -- which is removably secured to the pressure-reducing unit with which it delimits an internal utilization chamber which is supplied with low-pressure gas via said outlet of the pressure-reducing unit and which is connected to the upstream end of said bleed duct; -- which is rotatable relative to the pressure-reducing unit between: i) a first angular end position for installing the cap on or removing it from the pressure-reducing unit; ii) and a second angular end position for securing the cap to the pressure-reducing unit, i) a first angular end position for installing the cap on or removing it from the pressure-reducing unit; ii) and a second angular end position for securing the cap to the pressure-reducing unit,