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The Helium Escape Valve – What Is It, How Does It Work, And Do We Need One?

August 13, 2019

BY Ed Estlow


We all know what a helium escape valve is, right? That weird, circular fitting on the side of some dive watch cases like the Rolex Sea-Dweller, usually at nine o’clock, sometimes ten o’clock. All the best dive watches have them. That’s how you know you’ve got a genuine, gnarly tool on your wrist. Right?

Well, not so fast.

Rolex helium escape valve

You know what a helium escape valve does right?

The Helium Escape Valve

It turns out that helium gas escape valves, or helium valves, may actually be a liability in a dive watch, rather than a benefit. To learn why that might be, let’s take a look at the He valve (He is the element symbol for helium – sometimes marked on manually operated, crown-style valves like the Omega Seamaster Planet Ocean). What is it? What does it do? How does it work, and why might a diver need it?

Rolex Sea-Dweller helium escape valve

The Rolex Sea-Dweller is the watch that helped pioneer the helium escape valve.

This feature is typically found on a professional dive watch. We will take the modern Rolex Sea-Dweller for example.

First, you need to know that a helium molecule is extremely small – among the smallest of all molecules. Under the right circumstances (like extended periods of high pressure), the tiny size of helium molecules allows them to sneak past the seals of a watch, where water molecules or even molecules of the other gases that make up our air are too large to fit.

Omega helium escape valve

Some brands like Omega use manually operated, crown-style helium escape valves on their professional dive watches.

So after spending an extended period of time under external pressure, helium molecules can build up inside a watch, until that external pressure gets released. That’s when the built-up helium, which has now pressurized the inside of the watch case, may well blow the crystal right off the watch. Not fun. That kind of thing will take your eye out.

To prevent such an occurrence, a helium escape valve automatically allows built up helium molecules to leave the watch during decompression, as the watch returns to a neutral, sea level pressure environment. It’s a one-way valve so it only lets pressure out of the watch. It’s designed to never allow water – a larger molecule – to pass into the watch. (If helium gets in by that route, it’s OK – the valve’s whole purpose is to let helium out. Back out, so to speak.)

This feature was first added on the Double Red Sea-Dweller, but Rolex decided to continually advance their technology.

But wait! Why the heck would helium get into the watch in the first place?

Rolex Deepsea helium escape valve

All of the Rolex Deepsea Sea-Dweller watches have helium gas escape valves.

Well, in order to counter the effects of nitrogen, which can have a narcotic effect when diving at great depths – something inevitable for commercial divers temporarily living in deep water habitats, helium largely replaces the nitrogen in the gas mixture that the divers breathe. The vast majority of gasses will create a similar effect to nitrogen narcosis under these deep-diving circumstances; however helium is one of the few gasses that does not have a narcotic effect, and is the go-to option to replace nitrogen in most deep-sea commercial diving applications.

So that’s how helium gets into divers’ watches. It’s driven in by that increased pressure while divers are residing in their dry living quarters at depth. And when they finally come back to the surface and decompress after days or weeks at depth (and increased pressure), their watches are liable to explosively pop off their crystals if that helium build-up isn’t properly released.

But by that explanation, you can see that the valve doesn’t have anything to do with actual diving. Instead, it has to do with living in a dry pressurized environment, specifically when not diving.

Rolex Sea-Dweller helium escape valve

The Sea-Dweller is one of the few Rolex watches that has an engraving on its caseback.

That’s why a very specialized professional/ commercial diver might need a watch with a helium escape valve. Conversely, if a diver is not living in a pressurized habitat for days or weeks, they have no need for a watch equipped with a helium valve, regardless of how deep they may dive.

And that’s where such a valve’s potential liability comes in. As a diver friend and watch writing associate of mine once said, “we’re a little squeamish with any extra holes in the cases of our dive watches.”

The truth is that any additional holes represent an additional point of failure – a potential leak path. If the valve should fail for any reason, the watch can flood, effectively leaving the wearer with a broken tool. In days of yore, this could be a dangerous (and likely deadly) situation to be in. Now? It only represents an expensive repair bill.

So why are brands putting helium valves in so many dive watches?

Rolex Sea-Dweller 126600 - helium escape valve

Like its predecessor, the new 43mm Rolex Sea-Dweller is fitted with a helium escape valve.

As you can imagine, most folks who have an opinion think the answer lies in marketing. Helium escape valves are cool. While they do represent a wonderfully-elegant solution to a highly specific (and seldom encountered) problem, they also just seem like they belong on a dive watch, as if the watch is in some way less of a tool if the valve is not there. So their presence helps sell the watch – despite the fact that few who buy the watch actually scuba dive at all, let alone find themselves in saturation diving situations where a helium escape valve would actually be of any use.

And let’s be honest. With the availability of modern dive computers, the dive watch as a vital diving tool is an anachronism. Any liability we writers can conjure up is on paper only, because the vast majority of divers operate in the cube farms of Corporate America, not the kelp beds of the continental shelf.

helium escape valve on Rolex Sea-Dweller

While a helium escape valve enables a watch to be used for saturation diving, it also represents an additional gasket that must be maintained.



One Response to “The Helium Escape Valve – What Is It, How Does It Work, And Do We Need One?”

  1. S says:

    The He valve sounds a lot like the Hesalite crystal on an Omega Speedmaster. It’s there in case you get to go to the space.

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