8 Discussions and CommentsMember since Oct. 15, 2001
Will the Aquatimer survice a dive in compression chamber without a helium escape valve?
Is the surgery steel harder than ordinary steel - and more scratch resistant?
Thanks in advance,
Thomas Wagner
UnknownJan. 22, 2002
The specific member who posted this comment can not be uniquely identified by username.
Pushing my technical knowledge....
Hi Thomas,
I'm not expert on diving and the physics involved, but a friend of mine is a research physicist at a major university and he wrote about helium valves:
"...it should be clear that there is no reason to have a helium release valve unless you 1) use diving gas mixtures that include helium and 2) dive using a bell and/or compression chamber. Only highly trained professional divers should do either of the above. It should also be clear that it has nothing to do directly with the depth rating of the watch. The only relation between helium relief valves and the depth rating of a watch is that really great depths are only accessible by saturation diving. Dives in excess of 2000 feet are possible using these techniques. "
Given that, I suspect the Aquatimer is not meant for compression chambers, but I'm not sure why you would want to do that. The reasoning of my friend is highly technical, but basically he said:
"While a diver is in the chamber, his watch is exposed to the pressurized gas mixture. Helium, because its two electrons form a closed quantum shell, is very very inert. It can diffuse though many materials and can easily get into a watch case though both the seals that keep water out and though the crystal. Thus, over days spent at pressure, helium will diffuse into the watch. (Note, it is only while the diver is in the chamber or bell that this happens. While he is actually in the water diving, it is not a problem.) When the diver decompresses, the helium may not have time to diffuse out of the watch, with the result that the gas pressure on the inside becomes greater than the pressure on the outside. Now, dive watches are designed to keep water at pressure out, not to hold gas at pressure in. At some point something has to give. Usually, the watch crystal explodes out of the watch. Naturally, this is a very disconcerting thing to happen in your little compression chamber, and divers do not like it. It is also not particularly good for the watch. The solution is to have a valve that releases the helium as the divers decompress in the chamber. This then is the purpose of the helium escape valve. "
In terms of steel, it is my understanding that surgical steel has a higher rating (on the Mohs scale of hardness) but because it is highly polished superficial scratches cannot be avoided. This is true for all such materials --and I'm not sure a 10% or so (ore whatever) hardness rating will retard scratches that much better. I think you'd find the titanium will show scratches less.
8 Discussions and CommentsMember since Oct. 15, 2001
--------
Thanks Michael for your answer about saturation diving.
Is it possible to ask the engineer that designed the watch if it will survive a compression chamber, as I am trying to convince myself about the Aquatimer being the ultimate diving watch?
57 Discussions and CommentsMember since March 23, 2001
I wouldn't be so sure...
that the Aquatimer isn't fit for Helium filled saturation diving enviroment. First of all Helium has a lower solubility in greases than Nitrogen, so it's capability of migrating through the grease that lubricates the seals is quite insignificant. Then it's really new to me that Helium passes through Sapphire crystals; while a certain degree of gas permeability is a fact for plastic materials (old acrylic or plexiglas?), I have never heard of such a phenomenon for current sapphire crystals. Helium is regularly traded and conserved in standard commercial tanks at 3000 psi / 200 bar without leaks or pressure drops. I suspect early watch explosions were due to poorly lubricated or damaged seals, crowns being opened for winding or adjustment (insufficient winding movement in a saturation enviroment or handwind watches) and perhaps plastic crystal permeability. I think it's very likely that an Aquatimer can be safely used in a saturation diving enviroment if the crown is not unscrewed.
724 Discussions and CommentsMember since March 22, 2001
Your friend is correct up to a point.
Hi Michael -
Your friend is absolutely correct about how helium will infuse inside the case of the watch under pressure in a chamber over a period of time. The nature of saturation diving and the consequent time spent inside a chamber at depth will take you there.
He is right that a helium release valve will deal with the issue; it is not correct to say or suggest that it is the ONLY way to do so. It is one way.
Water-resistant watch cases are always built to withstand external overpressures and rarely is mauch thought given to the situation where the internal pressure exceeds that outside the case. This is the opposite situation from an airliner, which is designed to cope with exactly that, an internal pressure that exceeds the external.
The point is, it can be done without a valve. IWC touts, for instance, that its pilot watches will withstand an internal overpressure equivalent to 0.8BAR, the type of thing you might experience in a cabin decompression at 35,000 feet.
One typical way (there are others) that an airliner's pressure vessel achieves its effect is through the use of doors that are plugs. When these doors are closed, they pull in from the outside and then are rotated to align parallel to the plane of the door. They are then pushed into position and locked. The edges, or sides, of the door have beveled edges, sloping inwards from the inside of the door to the outside. This means that as the pressure inside the hull pushses on the door, it makes an even tighter seal.
I do not know the specific means that IWC used to achieve it but I remember reading a comment by them once that the design of the Aquatimer was such that it did not need a helium overpressure relief valve, but was capable of withstanding those pressures without one.
As I recall, it was the divers of COMEX who first experienced the joys of dodging ricocheting high speed crystals that had come flying out of their Rolex Submariners in the crowded quarters of a decompression chamber. The SeaDweller was Rolex's response to the problem.
Regards,
OCD
Last edited: 2 March, 2011 - 18:26
UnknownJan. 24, 2002
The specific member who posted this comment can not be uniquely identified by username.
57 Discussions and CommentsMember since March 23, 2001
Not the case with the Aquatimer >
A quick glance at the technical drawing of the crown seals that MF published recently, shows there's no one-way seals in the crown. I still believe the Aqua just keeps helium out, but a word from Schaffhausen might clarify this point (or maybe it wasn't designed for bell workers at all).
724 Discussions and CommentsMember since March 22, 2001
I disagree with what you say here.
Hello Simone -
I suspect that there is a misunderstanding at play.
I never said, or suggested, that there were "one way seals" in the crown of the Aquatimer.
I did say that a helium over-pressure relief valve was one way (in the sense of one method, or manner) of dealing with an internal overpressure and that it was not the only manner.
Helium gets in through the metal itself, not just the gasket seals and O-rings, I believe. The small size of the helium moleclues permits this, under pressure.
I believe that I reported accurately what was posted once by Schaffhausen. It would be great if somone there could clarify for us whether or not the Aquatimer design is, in fact, inherently resistant to internal overpressures from infused helium at high partial pressures.
It would be absolutely pointless to design and produce a dive watch resistant to 2000 meters that is not suitable for HELIOX diving operations. Compressed air (SCUBA) starts to develop a variety of problems for a diver below 100 feet but can still be used for very short periods at somewhat deeper depths, perhaps in the 150 feet range. Below 100 feet NITROX mixtures extend bottom time and safety compared to compressed air and can take you somewhat deeper than compressed air. Below 180 to perhaps 200 feet you fast get into the range of HELIOX.
The deeper you go, the longer the decompression regimen to return to the surface. As a practical matter, this mandates that the divers, if doing a large volume of work, live at depth in a chamber pressurized to that depth, breathing HELIOX.
Frankly, there really isn't any functional point at all to making a watch whose WR rating is deeper than a few hundred meters that is not capable of dealing with the helium question. (Yes, some have done that.)
57 Discussions and CommentsMember since March 23, 2001
I disagree too!
Who said helium passes through metal? I've used helium for years and I've heard the myth that it passes through seals, BUT it never happens if they're properly lubricated! You can buy and keep helium in tanks and it stays there. I've kept a tank filled with helium @ 200 bar (2000 meters depth equivalent) for one year to check it personally: not one single Bar of helium escaped. What about the Hydrogen molecule, which is much smaller, and has been used by Comex as well, doesn't it pass through metal as well? Let's separate myth from facts, shouldn't we? Also, divers dive much deeper than what you say (I know several people that dove beyond the 400/500 feet range (150 meters) and what they're looking for is a tough watch; the idea of a watch that goes to 2000 meters is just that: a very tough watch.
Is the surgery steel harder than ordinary steel - and more scratch resistant?
Thanks in advance,
Thomas Wagner
Hi Thomas,
I'm not expert on diving and the physics involved, but a friend of mine is a research physicist at a major university and he wrote about helium valves:
"...it should be clear that there is no reason to have a helium release valve unless you 1) use diving gas mixtures that include helium and 2) dive using a bell and/or compression chamber. Only highly trained professional divers should do either of the above. It should also be clear that it has nothing to do directly with the depth rating of the watch. The only relation between helium relief valves and the depth rating of a watch is that really great depths are only accessible by saturation diving. Dives in excess of 2000 feet are possible using these techniques. "
Given that, I suspect the Aquatimer is not meant for compression chambers, but I'm not sure why you would want to do that. The reasoning of my friend is highly technical, but basically he said:
"While a diver is in the chamber, his watch is exposed to the pressurized gas mixture. Helium, because its two electrons form a closed quantum shell, is very very inert. It can diffuse though many materials and can easily get into a watch case though both the seals that keep water out and though the crystal. Thus, over days spent at pressure, helium will diffuse into the watch. (Note, it is only while the diver is in the chamber or bell that this happens. While he is actually in the water diving, it is not a problem.) When the diver decompresses, the helium may not have time to diffuse out of the watch, with the result that the gas pressure on the inside becomes greater than the pressure on the outside. Now, dive watches are designed to keep water at pressure out, not to hold gas at pressure in. At some point something has to give. Usually, the watch crystal explodes out of the watch. Naturally, this is a very disconcerting thing to happen in your little compression chamber, and divers do not like it. It is also not particularly good for the watch. The solution is to have a valve that releases the helium as the divers decompress in the chamber. This then is the purpose of the helium escape valve. "
In terms of steel, it is my understanding that surgical steel has a higher rating (on the Mohs scale of hardness) but because it is highly polished superficial scratches cannot be avoided. This is true for all such materials --and I'm not sure a 10% or so (ore whatever) hardness rating will retard scratches that much better. I think you'd find the titanium will show scratches less.
Regards,
Michael
Thanks Michael for your answer about saturation diving.
Is it possible to ask the engineer that designed the watch if it will survive a compression chamber, as I am trying to convince myself about the Aquatimer being the ultimate diving watch?
Thanks for your enthusiasm,
regards, Thomas Wagner
that the Aquatimer isn't fit for Helium filled saturation diving enviroment. First of all Helium has a lower solubility in greases than Nitrogen, so it's capability of migrating through the grease that lubricates the seals is quite insignificant. Then it's really new to me that Helium passes through Sapphire crystals; while a certain degree of gas permeability is a fact for plastic materials (old acrylic or plexiglas?), I have never heard of such a phenomenon for current sapphire crystals. Helium is regularly traded and conserved in standard commercial tanks at 3000 psi / 200 bar without leaks or pressure drops.
I suspect early watch explosions were due to poorly lubricated or damaged seals, crowns being opened for winding or adjustment (insufficient winding movement in a saturation enviroment or handwind watches) and perhaps plastic crystal permeability.
I think it's very likely that an Aquatimer can be safely used in a saturation diving enviroment if the crown is not unscrewed.
Last edited: 2 November, 2011 - 16:17
Hi Michael -
Your friend is absolutely correct about how helium will infuse inside the case of the watch under pressure in a chamber over a period of time. The nature of saturation diving and the consequent time spent inside a chamber at depth will take you there.
He is right that a helium release valve will deal with the issue; it is not correct to say or suggest that it is the ONLY way to do so. It is one way.
Water-resistant watch cases are always built to withstand external overpressures and rarely is mauch thought given to the situation where the internal pressure exceeds that outside the case. This is the opposite situation from an airliner, which is designed to cope with exactly that, an internal pressure that exceeds the external.
The point is, it can be done without a valve. IWC touts, for instance, that its pilot watches will withstand an internal overpressure equivalent to 0.8BAR, the type of thing you might experience in a cabin decompression at 35,000 feet.
One typical way (there are others) that an airliner's pressure vessel achieves its effect is through the use of doors that are plugs. When these doors are closed, they pull in from the outside and then are rotated to align parallel to the plane of the door. They are then pushed into position and locked. The edges, or sides, of the door have beveled edges, sloping inwards from the inside of the door to the outside. This means that as the pressure inside the hull pushses on the door, it makes an even tighter seal.
I do not know the specific means that IWC used to achieve it but I remember reading a comment by them once that the design of the Aquatimer was such that it did not need a helium overpressure relief valve, but was capable of withstanding those pressures without one.
As I recall, it was the divers of COMEX who first experienced the joys of dodging ricocheting high speed crystals that had come flying out of their Rolex Submariners in the crowded quarters of a decompression chamber. The SeaDweller was Rolex's response to the problem.
Regards,
OCD
Last edited: 2 March, 2011 - 18:26
A quick glance at the technical drawing of the crown seals that MF published recently, shows there's no one-way seals in the crown. I still believe the Aqua just keeps helium out, but a word from Schaffhausen might clarify this point (or maybe it wasn't designed for bell workers at all).
Last edited: 2 November, 2011 - 16:17
Hello Simone -
I suspect that there is a misunderstanding at play.
I never said, or suggested, that there were "one way seals" in the crown of the Aquatimer.
I did say that a helium over-pressure relief valve was one way (in the sense of one method, or manner) of dealing with an internal overpressure and that it was not the only manner.
Helium gets in through the metal itself, not just the gasket seals and O-rings, I believe. The small size of the helium moleclues permits this, under pressure.
I believe that I reported accurately what was posted once by Schaffhausen. It would be great if somone there could clarify for us whether or not the Aquatimer design is, in fact, inherently resistant to internal overpressures from infused helium at high partial pressures.
It would be absolutely pointless to design and produce a dive watch resistant to 2000 meters that is not suitable for HELIOX diving operations. Compressed air (SCUBA) starts to develop a variety of problems for a diver below 100 feet but can still be used for very short periods at somewhat deeper depths, perhaps in the 150 feet range. Below 100 feet NITROX mixtures extend bottom time and safety compared to compressed air and can take you somewhat deeper than compressed air. Below 180 to perhaps 200 feet you fast get into the range of HELIOX.
The deeper you go, the longer the decompression regimen to return to the surface. As a practical matter, this mandates that the divers, if doing a large volume of work, live at depth in a chamber pressurized to that depth, breathing HELIOX.
Frankly, there really isn't any functional point at all to making a watch whose WR rating is deeper than a few hundred meters that is not capable of dealing with the helium question. (Yes, some have done that.)
Regards,
OCD
Last edited: 2 March, 2011 - 18:26
Who said helium passes through metal? I've used helium for years and I've heard the myth that it passes through seals, BUT it never happens if they're properly lubricated!
You can buy and keep helium in tanks and it stays there. I've kept a tank filled with helium @ 200 bar (2000 meters depth equivalent) for one year to check it personally: not one single Bar of helium escaped.
What about the Hydrogen molecule, which is much smaller, and has been used by Comex as well, doesn't it pass through metal as well?
Let's separate myth from facts, shouldn't we?
Also, divers dive much deeper than what you say (I know several people that dove beyond the 400/500 feet range (150 meters) and what they're looking for is a tough watch; the idea of a watch that goes to 2000 meters is just that: a very tough watch.
Last edited: 2 November, 2011 - 16:17
is exactly what we need to clarify this..
I still hope to find the Aquatimer to be the ultimate diving watch!
Regards, Thomas Wagner
.