Helium Escape Valve
A helium escape valve is a small valve that lets helium atoms vent out of the case during decompression after a saturation dive. As ambient pressure drops, trapped helium would otherwise push against the crystal, so the valve releases it. It only matters to professional saturation divers and is unnecessary on most watches.
At a glance
- Component type
- Pressure relief valve
- When it acts
- Only during decompression after a saturation dive
- Types
- Automatic (self-opening) and manual (hand-operated)
A helium escape valve is built not for ordinary diving but for the very specific conditions of long saturation dives. The helium-rich breathing gas in the pressurised chambers a diver lives in for days slowly works its tiny helium atoms past the watch's seals and into the case.
The problem appears during decompression
Helium causes no trouble during the dive itself, only on the way back to the surface. As the chamber is decompressed, helium inside the case cannot escape as fast as the pressure drops, and the pressure that builds up inside can pop the crystal off.
- Automatic valve: opens by itself once internal pressure crosses a set threshold and vents the helium
- Manual valve: a second screw-down port the diver unscrews by hand and keeps open throughout decompression in the dry chamber
The valve releases that pressure in a controlled way, preserving the case's overall water resistance.
Unnecessary for most owners
In everyday wear, and even in recreational scuba, helium never enters the case, so the valve does nothing. The real toughness of a dive watch lives in its screw-down crown and solid gaskets. For more, see our guide to the best dive watches under £500.
Examples
The helium escape valve was developed for commercial diving scenarios where saturation divers live under a helium breathing mix for days. It is therefore only meaningful on specialised deep commercial and military dive watches, not for recreational scuba.
Comparison
Whether a watch needs a helium valve depends entirely on the kind of diving.
| Option A | Option B | Notes |
|---|---|---|
| Saturation diving | Recreational scuba | A saturation diver lives under a helium mix for days and needs the valve; a recreational diver never gets helium into the case, so the valve is entirely redundant for them. |
Related terms
Frequently asked questions
What is the difference between an automatic and a manual helium valve?
An automatic valve opens by itself once internal case pressure crosses a set threshold, with nothing for the diver to do. A manual valve is a second screw-down port, similar to a crown, that the diver unscrews by hand at the start of decompression and keeps open throughout, screwing it back down only once atmospheric pressure is reached.
Does a helium escape valve reduce water resistance?
A well-designed valve does not compromise water resistance. An automatic valve opens one-way only when trapped helium exceeds a set pressure, and does not let water in. A manual valve stays screwed down and sealed during the dive. Still, any extra opening is one more point to watch at service.
What is the difference between an automatic and a manual helium valve?
An automatic valve opens by itself once internal case pressure crosses a set threshold, with nothing for the diver to do. A manual valve is a second screw-down port, similar to a crown, that the diver opens by hand at the surface after decompression.