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 or under saturation.

When commercial divers operate at great depths, they often spend prolonged hours in diving bells under pressure breathing a breathing gas mix like trimix or similar, that contain the gases helium or hydrogen. Since helium atoms are the smallest natural gas particles found in nature, these gas atoms are able to work their 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 the decompression stops during resurfacing aren't long enough, a pressure difference builds up between the trapped gas(es) inside the watch case and its environment. Depending on the construction of the watch case and crystal, this effect can cause damage to the watch, such as the crystal popping off.

While 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 co-created the helium escape valve in the 1960s (first introduced in the Rolex Submariner/Sea-Dweller and the Doxa Conquistador): A small, spring-loaded one-way valve integrated in the watch case that is activated when the differential between the inner and the outside pressure reaches a critical level. As a result; the valve releases the helium, hydrogen and/or other gases used in the breathing gas mix trapped inside the watch case.

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