Much more than you thinK! Gas expand about 5.4times @35k feet [nt]

Aug 13, 2009,00:43 AM
 

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Lenses (Part Three): a shattering experience

 
 By: AndrewD : August 12th, 2009-02:33
I learned first hand why the hesalite lenses used on Omega Speedmaster Pro’s are the preffered material in space. Despite being unaware of any trauma to the sapphire lens of this Zenith Prime, after carefully laying it down in the watchbox the night befor...  

Strange

 
 By: dxboon : August 12th, 2009-03:31
Andrew, Do you have any idea what could have caused such large fractures in your Zenith's sapphire crystal? Is it a function of rapid pressure/temperature changes possibly? I don't know how this could've happened, short of you knocking your watch with sig... 

Shattering Experience.

 
 By: isquires : August 12th, 2009-08:57
About 8 years ago, I checked some watches in my Luggage. They were in an unpresserized cargo hold on U.S. Air going from L.A. to Charlotte NC. The lens popped out of the case but did not shatter. It was an essentially new ETA 7560 chronograph made by Hebd... 

Interesting story, BUCKO …

 
 By: AndrewD : August 12th, 2009-16:16
… If the theory is correct it suggests that the watch is impressively water (and air) tight. Someone with more physics background than me might be able to work out how much the air inside a watch case would expand at 35000 feet, but personally I would be ... 

Too many years since Physics classes

 
 By: AndrewD : August 13th, 2009-15:11
Thanks Andrew, that’s very helpful. Does an expansion of 5.4 times imply an increased pressure of 5.4 atmospheres? And in practice the much lower external temperature (minus 40 to 60oC) must reduce this expansion considerably. I guess that even if a watch... 

Wouldn't the expanded

 
 By: BDLJ : August 13th, 2009-20:31
...air simply leak out of the case? The pressure gradient in a watchbox in your house is going to be very shallow. Plenty of time to leak out....

No alien abduction theories?

 
 By: AndrewD : August 12th, 2009-16:13
Hi Daos, I don’t recall any anomalous atmospheric conditions that night, or aliens hovering overhead. The kids were already asleep and, as I mentioned, I was not aware of any trauma to the crystal during the day. Hopefully this is a once in a watch-collec... 

I got it...

 
 By: dxboon : August 12th, 2009-22:44
...look for Gremlins, Andrew! (photo courtesy of SFWeekly)...  

"They're here."

 
 By: AndrewD : August 12th, 2009-23:47
... or Poltergeist ? As long as they wind up my watches, I don't mind....  

Yikes!

 
 By: dxboon : August 14th, 2009-00:31
That's a creepy movie! *shivering* Daos

Well...a few possibilities...

 
 By: p@p@ : August 12th, 2009-04:30
you hit glass at the right spot even a small blow can cause this... extreme temperature or pressure or frequency...could do it.... you got pissed and threw it... somebody (dear...or not) got pissed at you and tried to hit you with something and blocked it... 

All great theories, ppcollector ...

 
 By: AndrewD : August 12th, 2009-16:07
… many of which made me laugh. I do agree that the right blow to a crystal, perhaps if it was under pressure at one point in the mounting, could do this. Just interesting that it did not happen while on my wrist. I guess Daos’ experience with the windshie... 

It's hard to tell...

 
 By: BDLJ : August 12th, 2009-17:42
....from the photos, so this may be completely erroneous. But since you cannot recall whacking it on anything, it appears that the installed crystal had too much pre-load around it's perimeter (eg crystal may be marginally oversized). The appearance of th... 

Compressive and tensile stress…

 
 By: AndrewD : August 12th, 2009-21:09
… I don’t know what sort of stress that is, but I may be suffering from it! Seriously though, I think you are right. I have been walking around with a ‘time' bomb on my wrist. That’s a very helpful explanation. Andrew

Mystery...

 
 By: doubleup : August 12th, 2009-14:47
My first thought was that there was some kind of resonance factor, but sounds highly improbable. Very strange, glad all is well. Looks traumatic. Very nice watch.

I have since stopped singing in the shower. [nt]

 
 By: AndrewD : August 12th, 2009-16:18
No message body

I'll still rock in the shower...

 
 By: chaser579 : August 12th, 2009-17:44
...(as long as she likes it...whatever! =:^D). However, methinks whether it's sythentic sapphire, rock crystal (a la Marie Antoinette watch by Breguet), Hesalite or whatever, it can crack in many different ways by many different means. Watch (no pun inten... 

What about Suction?

 
 By: isquires : August 13th, 2009-14:12
I once knew a girl that could suck the chrome off a trailer hitch. Don`t know what she could do to a watch crystal...? BUCKO