Its helium escape valve and unidirectional rotatable bezel make it a true professional diving instrument.
Bravery under pressure
In deep water
Those who venture into the deep know that the dive is but half the journey. To also meet the challenge of the ascent to the surface, Rolex created the Sea-Dweller in close partnership with Comex professionals. Waterproof to a depth of 1,220 metres (4,000 feet), it was designed specifically for saturation diving. Thanks to its helium escape valve, the Sea-Dweller passes the ultimate test: gradually releasing internal pressure when the need arises.
Helium escape valve
Early saturation divers experienced a troublesome phenomenon that affected their watches during the decompression phase in hyperbaric chambers filled with breathing mixes composed largely of helium.
Helium atoms are so tiny that they can slowly penetrate the watch case through the gaskets, so the pressure inside the watch equalizes with the pressure inside the habitat. However, during a diver’s decompression process to be slowly brought back to normal atmospheric pressure, the gas is unable to escape from the waterproof case sufficiently quickly. The resulting pressure difference inside and outside the watch can damage the watch or force the crystal out of the case.
To address this issue, Rolex invented and patented the helium escape valve, a one-way valve which safely allows the helium trapped in the watch to be released when the difference between the watch's internal pressure and the pressure in the hyperbaric chamber is too high, without compromising the waterproofness of the watch.
This innovation brought the final touch to the resistance to pressure – both internal and external – of the Sea-Dweller’s case, resulting in a watch perfectly adapted to the requirements of deep-sea divers.
Built for deep-sea divers
The Triplock system was introduced in 1970 to equip the Sea-Dweller, the model designed for professional deep-sea divers. To further reinforce the waterproofness, Rolex engineers added a second O-ring inside the tube. This acts as a kind of airlock, safely keeping out even the minutest particles. Today, the Triplock system equips all the brand’s divers’ watches as well as a number of other Professional models.