Helium escape valve
Professional saturation divers spend long periods of time in a hyperbaric chamber, where the gas mixture they breathe contains a significant proportion of helium. The molecules are so small that they penetrate the watch case. During the decompression phase that enables divers to gradually eliminate the gas mixture absorbed by their bodies and returns them to normal atmospheric pressure, the helium cannot always escape from the watch case sufficiently quickly. This phenomenon can result in a build-up of pressure inside the timepiece, leading to damage or even separating the crystal from the case. To allow the gas to be released without compromising the waterproofness of the watch, the Sea-Dweller, Rolex Deepsea, and Deepsea Challenge are equipped with the helium escape valve. This unidirectional valve activates automatically when the pressure inside the case is too high.