[arachne] Re: Best tip of the year

Arachne at FreeLists---The Arachne Fan Club!

Steve,

In the real world gauge pressure *is* used; that is why we dove with pressure gauges. They told us how deep we had gone based upon the water pressure. But anyone who trained and was certified for SCUBA would have learned, and learned well, the concept/fact of cumulative TOTAL pressure. That is how sea level dive charts (decompression charts) are calculated; that is why the calculations for high altitude SCUBA decompression charts are far different from sea level. SCUBA is very real world, and not a bit laboratory -- honest!

Until you've been in 10' of water and had a 20' wave pass over you, popping an eardrum and hitting you with vertigo that is truly killer as the 40F water hits your inner ear, you might not be able to appreciate that aspect of actual (cumulative) pressure.

I've never seen a watch rated in "atmospheres"; they are rated in depth under water. That could well be because many people, like you, would forget that the ambient one atmosphere of pressure must be taken into consideration.

However, to answer your question: If a watch is rated at one atmosphere of pressure, that means you can go under water if you'd like but the watch can't survive.

l.d.
====

Steve wrote:


You're talking absolute pressure, which is pretty much only done in laboratories. In the real world, pressure is measured in gauge pressure.

  Just inflate your tires to observe this fact.

If a watch is rated as being water resistant to 1 atm, do you suppose they're telling you not to go underwater at all? 


Arachne at FreeLists
-- Arachne, The Web Browser/Suite for DOS and Linux --

Other related posts: