MWC “Depthmaster” 100atm / 3,280ft / 1000m Water Resistant Military Divers Watch in Stainless Steel Case with Helium Valve (Automatic)

All MWC 100ATM models are fitted with a helium escape valve, people often ask us how helium gets into a dive watch in the first place and the answer is very simple, essentially a helium molecule is among the smallest of all molecules. What this means is because they are so small even though the seals are working fine to keep water out the helium molecules can still get through and enter the watch even though other gases and water cannot.

The main users professionally of watches with helium escape valves are saturation divers who spend long periods of time at great depth with high pressure, the result is that the helium molecules can build up inside the watch creating pressure inside the case, this can inflict serious damage to the watch and even blow out the crystal or crown when it’s unscrewed, this is potentially extremely dangerous if for example you are just checking or resetting the time, it can also potentially write off the watch. What the helium escape valve does is automatically allow the helium molecules to escape from the watch during decompression when the watch returns to normal standard sea level pressure. The valve is only one way so it lets the helium out but prevents anything external getting in.

For anyone who does not know why the helium is an issue, it’s important to understand why helium is employed for deep diving. The reason is that helium is one of very few gasses which does not have negative effects such as we see with nitrogen which causes nitrogen narcosis, consequently helium is used to replace nitrogen in most deep-sea mixed gas diving applications.

In some situations, professional divers can operate at great depth for extended periods where they live in dry environments pressurised with an oxygen/helium mix. When the divers surface and decompress after days or even sometimes weeks this gas must be removed to prevent problem as mentioned earlier such as the crystal or crown being blown out which can potentially injure or even blind someone.

The reality is that most divers will not be living in a pressurized environment for days or weeks on end, this means they will have no need for a watch equipped with a helium valve, regardless of how deep they dive but with deep diver watches such as our 100ATM range, it’s essential the valve is there just in case it’s needed because the watch would not be fit for purpose without it.

This particular variant has a 12/24 Hour US pattern dial and is finished in brushed stainless steel. The movement is a high quality 24 jewel automatic NH35A with hacking function to enable synchronization. The movement also has a 41-hour power reserve.

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