κατι επισης σημαντικο για το moonwatch
But pressure works both ways. Yet none of the normal water-resistance features allow a watch to handle excessive internal air pressure, which can occur using most any form of pressurized environment--a deep diving chamber, a spacecraft or even in a commercial jetliner.
In a deep diving chamber using a helium rich air mixture, helium--the smallest molecule--seeps past the seals, allowing the watch's internal pressure to gradually equalize to the chamber's pressure. During decompression of the chamber, the helium cannot seep out fast enough, causing the pressure in the watch to exceed that outside of it.
A watch on the outside of the astronaut's spacesuit will be exposed to little or no air pressure when he steps out for a spacewalk or on the surface of the moon.
In a commercial jetliner, you are in a pressurized cabin because the air pressure at high altitudes is very low. On rare occasions, the cabin pressure may drop suddenly, causing the pressure inside the watch to be greater than outside of it.
The end result is that due to any these several reasons, the air pressure inside the watch becomes greater than the air pressure outside the watch. The tigher seals of a highly water resistant watch can prevent these pressures from equalizing as quickly as they might change in the environment. The weakest seal for handling internal pressure is that holding the watch's crystal. When internal pressure exceeds that seal's limits, the pressure will escape by causing the crystal to pop out.
