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Quiz: Which has the highest pressure rating?
A common topic on watch related websites is the Water Resistance ratings of various watches.
The common element in achieving WR is the humble O-ring - whether the watch is a 30m rated dress watch, a 610m Rolex Sea Dweller (see Dr Strong's recent post) or the completely over-specified 1000m+++ watches.
In the (poor quality) photo below are 5 O-rings. Scaled against a Euro 10c coin.
The challenge is: Can you guess which has the highest pressure resistance and which has the lowest??
Bonus points for those who can identify the O-ring application.
(disclaimer: for any engineers or specialists out there...yes, there are factors beyond the mere O-ring that determine the pressure rating, but let's let it roll....)
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Quiz: Which has the highest pressure rating?
A common topic on watch related websites is the Water Resistance ratings of various watches. The common element in achieving WR is the humble O-ring - whether the watch is a 30m rated dress watch, a 610m Rolex Sea Dweller (see Dr Strong's recent post) or ...
No expert neither...
One Highest and Four lowest. My reasoning is that the more the O ring can be compressed the more it will adapt to its environment and seal properly. My model behind it is that an O ring in a watch is very slim and compressable. Regards, Yves
My uninformed guess
1 is lowest since it's big and wobbly. 3 is highest since it's thick and small.
Fascinating question ...
... I would have thought it was easy, but then I started to imagine some of the variables. Thickness, compressibility, surface area exposed to the pressure, and who knows what else a real engineer might think of. So I will guess 3, 1, 2, 4, 5. Look forwar...
O-ring design...
..is one of those things where it's so simple, yet you get into the detail you just start doubting! Let's take a crown o-ring for that 200m watch. Where do we start? Well, unless we're happy with a 15mm diameter crown, we're restricted to small <5mm OD o-...
Some Hints:
2 of the O-rings are from a watch. 2 of the O-rings are from Scuba equipment. 1 of the O-rings is from an Engine.
The Answers
First off, thanks to those who took the plunge on such a vague quiz. This was a bit of a dishonest question. As I alluded, there are a plethora of factors that contribute to the pressure resistance of an o-ringed joint. However I tried to find as diverse ...
Challenger
Thanks for the quiz and the education. A lot of fun. O-rings are forever associated in my mind with the Shuttle Challenger disaster. When o-rings fail, they can do so in spectacular and disastrous ways. Andrew
And Feynmann...
...dipping an o-ring into the glass of ice-water to demonstrate the change in o-ring response at lower temps. There's a humungous amount of info on the Challenger disaster, but as I understand it, the o-ring failure was caused by: An uneven groove depth a...
hey Ben, you could have let it run until i'd woken up as i knew all the answers
honest guv'nor i did, i knew them all dishonestly knowledgable Graham
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Sorry, G.
Thought you were being shy. I have some other ideas that I'll make sure you get the chance to guess at...