Those high pressure numbers quoted for watches may also take into account the differences between static and dynamic pressures. Even if my watches of flashlights won't be thrown into the water more than one meter deep I may try to take them out fast. I have never measured my arm velocity but I believe I should be able to exceed 5m/s. I think that alone would add more than 0.1 atm of the dynamic pressure.
I don't know how to calculate the pressure of big rain drops or imposed during the impact when the light is accidentally thrown into the water but 0.1 atm also doesn't sound really safe here. Maybe someone with a background in physics better than mine could comment on that?
That's a fair point. I don't understand the maths and physics well enough (luckily Marduke was awake in maths class :wave
but at the same time, I don't know how the tests are actually performed.
All the IP codes I've seen for hand held equipment state a depth rather than atmospheric pressure. If you look up expensive marine radios (including submersible ones) they all seem to have IPX7, IP67 and IPX8 ratings of 1m to 5m (mostly 1 - 1.5m). They're not flashlights, but if you think about it they're used in a similar way eg: carried with clips or in pockets, often hand held while in use. It's common to see IP codes for this type of equipment, and it's hard to believe if they're dropped in a metre of water instead of carefully placed in it, they'll leak. Being used on boats I Imagine they
need to be splash and rain reisitant. Some are designed to float to the surface if dropped in water.
It's possible they're pressure tested much higher than the rating suggests (unlike watches), or they may even recreate conditions of use. Without knowing this it's hard to say how meaningfull the ratings are in use, but it's a widely accepted standard for everything from flashlights, marine radios and underwater boat lights to electronic components used in deep sea equipment. You sometimes see a Japanese JIS rating instead of, or along with an IP code, but they're very similar.
It would be great to have a manufacturer explain it, and find out if IPX8 can, in some cases, involve
nothing more than a > 0.1m static pressure test for 30 minutes. I'd be surprised, but also enlightended. I have noticed that while with watches you'll see "30 ATM - but no swimming", IP ratings state "IPX8, sumbersible in water at 1.5m... " or words to that effect.
The only thing I own that I know to be IPX8 rated is the E01, and this probably surpassed it's rating in the washing machine. Anyone know what the pressure might be during a spin cycle? :huh: