Abstract: An apparatus to deliver gas into a liquid comprising a container for the gas to be injected, which is connected to a compressed gas source (1) by means of an inlet duct, said gas delivering apparatus comprising at least one sensor to measure pressure and one sensor to measure temperature, wherein said container is a measurement chamber (9) of known volume, which is connected to a final delivery system or injector (10) by means of an outlet duct, wherein the final delivery system or injector comprises a long application tube with a diffuser that allows the gas to be divided into very small bubbles to facilitate its dissolution into the liquid.