Dear friends,
before couple of days I had a disagreement with a friend of mine about the need or not of the helium valve on a diving watch.
He explained to me that without it, an irreparable damage could occur in a watch during decompression procedure.
If this is true, why IWC don't have something like this on AT or DeeptTwo models?
interesting question, as a diver I would like to know too.
Based on what I have found and asked and have answered, there are two situations, whether the watch and diver is inside or outside a helium-saturated environment. a helium-saturated environment contains helium because divers are breathing a gas mix like trimix, which contains helium or hydrogen. at deep depths/under pressure, it is fatal to breathe pure oxygen.
When the diver and watch are inside such an environment - such as a dry dive suit (which covers & seals your watch within the suit), or deep sea exploration made possible with the use of diving bells or other vessels - the helium may seep inside the watch, and when the diving bell or vessel is brought to the surface, the helium may not seep fast enough out of the watch - so the helium release valve is used. The valve releases the helium, hydrogen and/or other gases used in the breathing gas mix trapped inside the watch case.
But for most divers who wear the watch on our wrist and enter the sea without such aids (dry dive suit/vessel), a helium valve is not necessary, as the watch is not in any environment that contains helium or other gases - its in sea water. The casing need only be strong enough to withstand the pressure.
Also, if in a dry dive suit, decompression safety stops are done during your ascent (for me that would mean 3 minutes every 5 metres of ascent), generally the helium would be able to escape sufficiently. But with a dry dive suit alone (without a vessel), you would not be able to spend enough hours underwater long enough for the helium built up to be significant that a release valve is necessary. I don't have the exact numbers but infer from information seen that you would have to descend to depths of 300m (in other words spend a really long time underwater, days perhaps) in order to be breathing enough helium to require a valve - in which case the sensible (perhaps only)thing to do is to use an exploration vessel.
This being the case, I infer that the rarity of any of us using the watch in an exploration vessel would have led to the design decision not to include the helium valve gauge.
That, at least, is my guess and understanding. Please correct me if I am wrong.
I know also that for all active AT collections save the AT 2000, the maximum depth is 12 bar = 80 metres.
AT 2000 can withstand pressure up to 1333 metres (200 bar). This would be the question mark for me, based on what I have written above, on why the AT 2000 would not require a helium valve - because at this depth you probably would.
Alternatively, it could also mean that the deep diver with the AT 2000 simply needs to ensure that the helium escapes during the ascent.
Dmitiris,
This issue has been discussed before, and there should be much in the archives.
But if I recall a helium valve is only needed in saturation diving, which involves depths that not amateur would ever attempt. For all recreational diving, a helium valve isn't necessary (which is why only one major Swiss watch company uses one on only one of its models, and not even their most famous diving watch).
Thanks Michael, yes the archives should have been my first port of call.
Interesting discussions. Many links further from these archived threads are no longer available, although these two discussions are to me very insightful.
Suffice to say:
a) this discussion & issue is for most intents and purposes purely theoretical, as Michael rightly pointed out, the typical IWC collector is unlikely ever to dive to depths so deep as to necessitate long stays in a helium/mixed gas-saturated environment - which is the only reason why a helium release valve would be necessary; and
b) there doesn't seem to be a consensus as to whether the AT 2000 (which can withstand pressure up to 200 bar so really deep diving), could similarly prevent or handle helium/gas buildup within the watch casing even without a helium release valvue. some say it already can, others disagree. if it can, then may I just add my humble opinion that this for me makes the AT 2000 truly a magnificent watch.
I would absolutely love to hear from commercial divers who have used/tested the AT 2000 to such limits, although I know this is not going to make much practical difference to most forum participants - do feel free to email me privately. A very big thank you in advance from me :)
Shing,
thank you for your valuable informations. ;-)
Gents, Michael nailed this one SPOT ON !
Whilst I agree with most everything that Shing states here - the key to the whole discussion (and also reflected in Shing's posting" is Saturation Diving as mentioned by MF.
In practice, this means days on-end spent at pressure [ not necessarily in water - the commercial divers enter into underwater chambers/housing via airlocks, in order to sleep, eat, warm up etc. - and do so for practical and economical reasons of having to avoid multiple descents/assents (all which require lengthy and costly sessions in a hypobaric decompression chamber after each accent)].
When conducting this type of commercial diving, the divers are exposed to high levels of helium whereby part or all Nitrogen is removed from the breathing air thereby reducing the risks of a decompression (the Bends) accident. The "thinness" and permeability aspects of the Helium ensures that it reduces the risk of bubble formation - yet, it is exactly this quality of the helium, that as Shing correctly states, causes it to 'leak" under pressure past the normal seals and O rings in the watches - which THEORETICALLY could then cause an issue on surfacing.
In practice, and with recreational scuba diving (Sport Diving, there is no reason whatsoever to have Helium seals on the Aquatimers, and given that the recommended maximum depth for scuba is 30m and the absolute depth limit for SCUBA set by most diving organizations is 40m - all IWC Aquatimers depth ratings are more than sufficient for the job.
Have I taken my AT's deeper than 40m? Yes - but not as part of any scuba recreational dive. And neither should any one not properly trained do so.
Mark Levinsohn
Master Scuba Diver Trainer / Tec Deep Instructor # 933271.
Thanks, Mark. That's very helpful. I'm afraid I can't offer your expert perspective since my experience is limited to a swimming pool!
Thanks Mark. Great visual description of the environment and conditions commercial divers go into - these are true professionals.
Thanks Mark,
your post as (Master Scuba Diver Trainer), was very important to answer my question.
Is there any links that you can suggest me for scuba diving instructions?
Please if it's easy for you email me..
Hi guys, I have only just come across your Gas Valve chat.
I have been workshop manager for IWC UK for the last 12 years or so.
3 years ago I received an email from a guy who was in a decompresion chamber 250 meters down at the foot of an oil rig.
He had an Aquatimer 3536 and his dive partner had a Rolex with escape valve.
His partner had convinced him that his IWC would not survive their 2 week assent. I spoke at length to all concerned in IWC and the sumarised opinion was that the valve is a gimick or compensation for insufficent sealing of the watch. I relayed this to the diver and 3 weeks later he let me know that his watch was still functioning perfectly, now on dry land.
Good luck
Leo
Leo.sweeneypod@gmail.com
Interesting report; thanks.
Excellent. Good information to know.
THanks Leo.
Gents,
I found this very interesting as well - but Shing's calculations above seem wrong to me - isn't the pressure at 200 meteres approx. 200 bar, and approx. 8 bar at 8 meters?? In other words, an IWC watch like that AT Deep Two which can handle 120 bar can withstand the pressure down to approx. 120 meters?? (1000 kg/m3 * 9,8 m/s2 * 120 m = 1176 kPas = 117,6 bar)
Maybe our resident Dive Master Mark can clarify for us??
Thanks
Great info here, thanks people! As a leisure diver I have not taken dive watches beyond 40m, Deep 2 rated at 12 bar Skule equivalent to 120m. :) cheers!
rgds
ks
Hi guys, this is the depth-pressure calculation site I use, in case its useful.
Ah - of course, I moved the comma 1 decimal point too much! 12 bar = 120m - thanks for the correction KS!
And 200 bar equals 2000m for the AT 2000, not 1333m Shing :-)
The site you refer to also includes the 1 atm of air pressure at sea level but I think a point can be argued that the watch, as it was assembled at close to 1 atm, has that pressure internally from when it was sealed. Therfore, even if the diver's body must withstand the total pressure of 1 atm + the water pressure, the watch only must cope with the pressure difference from inside vs outside - the water pressure.
Just in the spirit of accuracy ;-)
hi IWC
i am a professional diver and will be going into SAT, i have been unable to find an answer to the previous questions posted. i will be in a helium environment for approx. 30+ days at a time, so will the watch malfunction while I'm in deco?
Hi Jonathan,
Great having you here. Can u advise which IWC u are wearing for your deep dive ? How deep are u going ?
Great post, everyone!
Since I'm very into ATs this is really interesting material, thanks!
Hello all,
Perhaps I could shed some light. I had posed this question and received a reply from IWC stating that the Aquatimer 2000 has been engineered to cope with internal over-pressure negating the need for a helium escpae valve. I don't believe there is another dive watch on the market that is designed to handle such internal over-pressures. The only other saturation diver on the market without a helium valve is the Seiko Marinemaster 300. The case is not designed to cope with internal over-pressure, rather the gasket system is designed to not let helium in at all. The Aquatimer, IMO exhibits a level of engineering that no other dive watch does.
Considering the price of an AT2000 I guess it is a pretty good watch. As Shing said...a great performer.
The problem with all of the watch ratings is that they are way off on the low end of the scale. And few are around to test the high end.
Please correct me if I am wrong but if the watch stays with the diver, also during decomression, this should provide enough time for the He to leak back out? Maybe the built up He would cause a problem if the watch is submitted to sudden decompression, for example by sending it to the surface in a basket with other stuff that has to be examined on the surface.
Looking forward to your expert opinions on this.
Kind regards,
Clemens
Basically.As I understand the physics of the helium escape valve and its function in relation to dive watches being subjected to considerable depths,the valve is there to release the helium gas,thereby to stop the watch from literally exploding,due to the enormous build up of pressure.