Helium release valve

A helium release valve, or helium escape valve, as it is also called, is a feature found on some diving watches. It provides functionality for professional divers operating at great depths for prolonged periods of time.

When commercial divers operate at great depths, they often spend prolonged hours in diving bells under pressure breathing a gas mix like hypoxic trimix or similar, that contain the gas helium. Since helium molecules are the second smallest found in nature, the gas is able to work its way inside the watch, around any o-rings or other seals the watch may feature. This is not a problem as long as the divers stay under pressure, but when they resurface, a pressure difference builds up between the trapped helium inside the watch and the environment. Depending on the construction of the watch case and crystal, this effect can cause damage to the watch, like making the crystal pop off.

Whilst many watch companies react to this effect by simply offering an even more robust case/crystal construction, Rolex and Doxa S.A. however thought of a different concept when they invented the helium escape valve in the 1960s: A small, one-way valve integrated in the case, sometimes featuring an additional screw-down crown on the side of the watch. When the diver starts to ascend he or she simply unscrews the valve's crown to the full open position, allowing any helium that may have been trapped inside the watch to escape during decompression. Usually used in a dry environment (inside a diving bell or in a saturation chamber), the fact that the valve is one-way also means that it can be opened while the watch (and diver) is submerged. Automatic helium release valves don't need any manual operation.

Helium release valves are primarily found on mechanical diving watches featuring depth resistance greater than 300 m (1000 ft). Models that feature a helium release valve include most of the Omega Seamaster series, Rolex Sea Dweller, some dive watches from the Citizen Watch Co., Ltd, all watches produced by Enzo Mechana, and selected Doxa and Oris models. Some more recent Breitling diving watches (Superocean models) also feature helium release valves, whilst other watch manufacturers such as Seiko still offer dive watches that are guaranteed safe for helium gas without needing an additional opening in the case in form of a release valve.

Gallery

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  An integrated Helium release valve as used by Rolex for their latest version of the Rolex Sea-Dweller, the Deepsea.
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  A manually operated Helium release valve as used by Omega for their Seamaster dive watches, here the Planet Ocean.