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If you’ve ever read a watch’s specs sheet, you may have seen the words “helium escape valve” on it. This is a feature typically found on professional divers’ watches from some of the world’s most famous luxury watch brands. But do you need one? To find out more, your trusted source for all Seiko parts talks about what escape valves are and how they work:
Helium escape valves are nothing more than a necessary evil made possible by the laws of physics. The thing with helium is that it is sporadic on earth, and as such, no one knows what happens to it when exposed to air. The only known fact is that helium is so tiny that it can sneak through microscopic gaps between the gaskets of a watch and escape into the atmosphere. Now, for obvious reasons, it would be bad for a watch to have all of its helium escape in the first few days on the wrist, and it would also be bad for it to lose all of its ability to resist water. So, the only logical solution is to have a way for the helium to leak out slowly over time, and for that, we need a helium escape valve.
A helium escape valve looks and functions almost exactly like a typical crown, except it is much smaller and will not screw in or out. They are typically about two millimeters in diameter but can range from 1mm to 3mm. They are located on the case at 6 o’clock and consist of, at most, a tiny metal pin that is set into the case. The pin is connected to the case with a small spring and an O-ring. This makes it so that pressure inside the case will push the pin out regularly as the case seals and pressurizes, allowing helium to escape slowly over time.
When it comes to the size of a helium valve, the smaller, the better. Smaller helium valves have a larger surface area to volume ratio, which means that they will lose helium faster and, therefore, need to be adjusted more. Most helium escape valves are adjusted once every couple of years. This is usually an in-house procedure, but some watches ship with a tiny screwdriver (or flathead) so that the owner can adjust the timepiece.
The Case Back
As you probably already know, some watch cases have a hinged case back that is usually held in place by a small screw. This is one of the best places for a helium escape valve to be located. This is the same reason why the helium escape valve is located on the case back – it gives the helium a larger area to escape from and, therefore, more surface area to volume ratio. This means that the helium will escape faster. The drawback of having a helium escape valve on the case back is that it is more susceptible to damage from impact, and it is exposed to more outside forces than the crown is.
For those wondering, yes, a helium escape valve is a feature that can only be found in watches that have been designed with professional divers in mind. However, some of the most famous watch manufacturers globally (Seiko, Rolex, and IWC, to name a few) use helium escape valves in their watches. This is why it is not uncommon to see a helium escape valve on a timepiece designed for land-going use. They are used in professional diving watches, and so, to comply with international diving standards, non-professional watchmakers must install them.
So, there you have it. A helium escape valve is a little pin strategically placed inside a watch case to allow helium to escape from the watch over time. This ensures that the watch will function properly once it has been taken off the wrist and worn on a dive. A helium escape valve may not be among the Seiko parts that you pay attention to but it is among the most important ones especially if you are a diver.
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