Recently someone commented on the site asking for an explanation of what a helium escape valve is and how it functions. Rather than write a brief comment in response I thought a more detailed explanation was in order for this essential feature of any serious dive watch.
Why Is It Necessary?
The purpose of a helium escape valve, or helium release valve as it is sometimes called, is to ensure that professional divers have access to a timepiece that can withstand the changes in pressurization inherent in diving.
Essentially when commercial divers operate at great depths, they often spend prolonged hours in diving bells under pressure breathing a gas mixture that contain the gas helium. As 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.
Whilst the diver remains in this artificially pressurized environment the invasion of helium molecules into the watch is not an issue. However, when the diver begins their ascent to the surface there is a risk that a pressure difference will build up between the trapped helium inside the watch and the environment. This can lead to damage to the watch, such as the crystal popping off.
To overcome this issue Rolex and Doxa S.A. collaborated in the 1960s to co-create the first helium escape valve which was debuted in the Rolex Submariner/Sea-Dweller and the Doxa Conquistador. This small, one-way valve integrated into the watch’s external casing activates when the differential between the inner and outside pressure reaches a critical level to allow helium trapped inside the case to escape.
The Final Word
Due to the nature of a helium escape valve they are primarily found on mechanical diving watches that feature a water/pressure resistance greater than 300 m (1000 ft). Chances are that unless you are a serious professional diver you will never actually use this feature but it does make a cool talking point. It is also indicative of the extensive functional capabilities of the humble wristwatch.