Reply With QuoteA complete guess, but liquids are less compressible than air so would possibly decrease the potential for a leak. Probably completely wrong.Originally Posted by Loki
Had a quick scan through this thread but am still wondering what is the purpose for liquid filling a watch?
A complete guess, but liquids are less compressible than air so would possibly decrease the potential for a leak. Probably completely wrong.
No real point, other than liking the aesthetic effect. There are, of course, commercially available oil filled watches. The concept appealed to me, but not the designs. Hence making one myself.
The original point is to totally negate the pressure difference between deep water (diving) and the inside of a watch.
The orignals (Beuchat, Bell & Ross, Sinn) all had slightly deformable cases (plunger caseback centre on my EZM2), so that as the external water pressure increased, a minimal deformation in the case shape ensured that the liquid filled watch pressed back just as hard as the water was pushing on the case. Thus all force trying to create a leak is balanced out and nullified. Only possible using an incompressible liquid that is an insulator, and a quartz movement.
As such an oil-filled watch can be very insubstantial (in terms of case and crystal thickness) and still waterproof to phenomenal depths.
This is simply not possible in an air filled watch. If you take it 10m down, the air inside wishes to half in volume if it is to balance the water pressure that wants to push past the seals or crush the whole watch. Even a deep recreational ND dive at 40m has the gas in the watch wanting to be 20% of the volume at the surface in order to balance pressure.
The watch cannot accomodate this, so instead it is sealed by force on the sealing gaskets, and using the structure of the watch itself.
So, rather than allow a balance of forces, your dive watch has to resist it an imbalance, and the caseback and crystal have to be thickened to do so.
When dive watches are tested to destruction, what usually happens is that the caseback crushes inwards and smashes into the movement.
One cool side effect of oil-filling is that with the absence of defraction index changes as you view the watch, it becomes magically visible from all angles, whether submerged or not. It really is quite odd to look at.
Of course, sealing technology is really good now, and WR ratings greater than any sat dive requirements are commonplace on quite modestly priced models. I have a Tactico Anko with a 1000m WR rating (and each one was tested) that cost £500.
Dave
Nice one thanks for the info
You’re a brave man! V cool. You must be both skilled and idle in equal parts!
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