We all know the beloved wart is there to release He gas that penetrates the watch in high pressure O2 and He environments. But how do you actually use it? Scenario 1: I am sheltering in a chamber at 200 ft. I need to ascend 100 ft to weld part of a structure. My watch will have excess 3 bars when I ascend. If I want to let out excess pressure how do I do that without letting in water? Do you just crack the valve for a sec and hope for the best? Is it a one way valve? I imagine if it were one way we wouldn't have to keep it tight. 2: We are done the job and team is returning to the surface. Do I open the valve for the ride up? Couldn't I have just opened the crown for the same effect? The number of divers who do this work is very limited so I imagine none of us has used one, but I would like to at least have a clue how it works. A little levity is also invited.
You would use the valve to release the gas as you are decompressing. That means you would be sitting in a dry decompression chamber as it changes pressures. The watch would not be underwater. Some saturation divers could take up to a week to decompress. While they are decompressing they are in a living quarters not in the water. This living quarters is a chamber that is under pressure that is changing slowly to perform the decompression.
I'm careful not to get my seamaster wet while watching the dishes. If I find myself suddenly at 40meters I have pissed off the Mrs. in some way.
Thanks, but you didn't answer either question. Could you just open the crown instead of the He valve? If you're ascending in the water, can it be used?
Unlike the crown, the HEV is a one way valve. As noted, it's not meant to be used except in a decompression chamber.
Based on some good old YouTube, the helium escape valve would be unscrewed when you are ascending and decompressing from your saturation dive. Typically in saturation diving circumstances and you have say, a diving chamber/bell, and then once inside the chamber you would unscrew your He crown for the duration of the ascension until you reach sea level and obtain equilibrium to surface pressure. With respect to the notion of using the He crown, the He escape valve is a 1-way valve and its design is specific for this functionality. The crown's function is different and not a 1-way valve in design. Would the crown let He escape too? I would think so, absolutely. Again, that's not its engineering and function. Having the He crown open while diving significantly reduces and impacts the watch's water resistance. So not a good idea at all to have the He crown unscrewed and in the open position while in the water. Hope this helps.
Having never owned a watch with such a valve, I always assumed that they required no operation at all, and I didn’t realise some have a screw down crown. Thanks for posing the question, OP.
Thanks Archer and Barqy, I guess the valve is useless then. When ascending in a dry chamber I can just open the crown and excess pressure will escape. You wouldn't need the specialized valve. If I'm working underwater and go up 100 ft (3 bar) I can't open the valve due to leak risk so have to depend on watch's strength against internal pressure. This rating isn't published by watchmakers so we have to guess it's much less. Once again the valve is useless.
I always thought that you unscrew the valve from the watch, insert it into a block of C4 plastic explosive, and then rotate the bezel to detonate the charge. It doesn’t work that way? Damn Bond movies ...
The He crown is the charge. It's just strong enough to blow the jail door. I find the garrote option more practical.
No, not really. You appear to be under the impression that when the crown is unscrewed, there is an "open" path to atmosphere - that is not the case. The seals that secure the crown against leakage are still engaged and doing their job, even with the crown unscrewed. Again, the valve is one way only, and is spring loaded to the closed position, so it takes pressure inside to unseat it. So if you choose to use your HEV in the rather unorthodox manner you are suggesting (again, it's meant to be used inside a decompression chamber) the watch will not be filled with water. When air is coming out of the watch under pressure, none is going in.
OK got it. I'll just keep it in the chamber if doing any work up higher. Seriously those guys must have to do some work at shallower depths than their chamber. I wonder what pressure it can take from the inside? Oh well I'm a little closer to 200. Soon I'll be able to sell my SM and get something with an auto valve. But then it won't look right, and it has to be titanium.
So couple of things... On the crown's ability to keep pressure in or out, there is a seal as I said that is in constant contact with the case tube, even when the crown is unscrewed and fully pulled out. Because people often have the impression that when the crown is unscrewed or pulled out, that it has no water resistance, I've had to prove to people that this is simply not the case. So here's a photo of an SMP with the crown unscrewed, and fully pulled out to the time setting position: Run through the pressure testing machine using the dive watch program, which firsts tests using a -0.7 bar vacuum, and then a +10 bar pressure - passed both tests: So this illustrates the kind of pressure that the seal can stop, and this would be the same pressure either coming from outside the case, or inside the case. So back to your suggestion that all you would need to do is open the crown after being down 100 ft, well this is the pressure of 100 m and the seal didn't leak. So this shows you that opening the crown is not effective at releasing at least +10 bar pressure from inside the watch. Second, you ask how much internal pressure the watch can take. Well it's not something I have photos of but I do have a video that I can explain a few things with. So when a watch fails a pressure test in the machine above, the one thing it won't tell you is the location of the leak, but there is an additional test that can be done on the machine that can prepare the watch for a water dunk test. Once a watch fails a test in this machine, I use an additional program called simply the "leak finder" test. What this does is it takes the pressure side of the test only, in this case +10 bar, and applies this to the case for a much longer period of time than in the normal test scenario. In the normal test the watch will be under that pressure for typically 90 seconds or so. In the leak finder test, this can extend for 5 minutes or more (the time depends on exactly what the machine sees is happening). By pressurizing the leaking case, it will eventually equalize the pressure inside and outside the case at the pressure inside the test chamber - again +10 bar in this case. The machine carefully measures the deflection of the case, and tells me if the leak is small enough to submerge the case in water. I simply have a glass of water standing by, and when the case comes out, I place it in the glass, and look for where the bubbles emerge, and this tells me the leak location. Here is a video of just that on an SMP case: So when the case was removed from the machine, the internal pressure was +10 bar, which then starts to drop slowly as the air leaks out - this is a very slow leak so the pressure would have stayed up higher for quite some time. So there is significant pressure inside this case at the moment the test chamber opens, and yet the watch does not burst apart. This tells me that at the very least the watch can hold several bars of pressure inside it without issue. Hope this helps you understand the capabilities of these watches a little better. Cheers, Al
It should be highlighted that 99% of us, or more, will never be breathing helium in a gas filled (dry) decompression chamber. This would be the only place where helium would sneak into your watch case. It would not enter while you are in the water. So, unless you find you scuba tanks being filled helium/oxygen instead of air, I would not worry about your valve needing to be used.
