ChatterBank0 min ago
A question for divers
Here we see people snorkelling down to a "Bubble Room" which is maybe at 20 meters' depth. What will be the air pressure inside the bubble? Is there any risk of the bends when they come (quickly) back to the surface after having spent time inside?.
Answers
Pressure = density * gravity * depth
sea water is approx 1025KG per meter cubed
Gravity is close as makes no real difference to 10m/ s2
Depth is 20meters
so at 20m P = (1025 * 10 * 20)
P = 20500 Pascals (which is just above 3 times atmospheric pressure once you've added the 1 atmosphere of pressure that is always present even on the surface)
The...
sea water is approx 1025KG per meter cubed
P = 20500 Pascals (which is just above 3 times atmospheric pressure once you've added the 1 atmosphere of pressure that is always present even on the surface)
08:30 Sun 29th Aug 2010
Pressure = density * gravity * depth
sea water is approx 1025KG per meter cubed
Gravity is close as makes no real difference to 10m/s2
Depth is 20meters
so at 20m P = (1025 * 10 * 20)
P = 20500 Pascals (which is just above 3 times atmospheric pressure once you've added the 1 atmosphere of pressure that is always present even on the surface)
The easiest way to figure out if there is a risk from the bends is to use a dive table. which shows that you can stay at that depth for about an hour and then come straight up without problems, anything over that you would need to make decompression stops on your way to the surface. for example if you stayed down for 200minutes you would need to stop at 20feet for 1 minute and then 10feet for 70 minutes!!
sea water is approx 1025KG per meter cubed
Gravity is close as makes no real difference to 10m/s2
Depth is 20meters
so at 20m P = (1025 * 10 * 20)
P = 20500 Pascals (which is just above 3 times atmospheric pressure once you've added the 1 atmosphere of pressure that is always present even on the surface)
The easiest way to figure out if there is a risk from the bends is to use a dive table. which shows that you can stay at that depth for about an hour and then come straight up without problems, anything over that you would need to make decompression stops on your way to the surface. for example if you stayed down for 200minutes you would need to stop at 20feet for 1 minute and then 10feet for 70 minutes!!
Well done, Chuck.
The only practical risk on the way to the surface is having a lungful of air at 20m ambient pressure, which will expand as you ascend, and could cause a simple pressure trauma if you held your breath. You'd need to breathe out constantly as you went up, to let the expanding air vent off. Breathing out underwater feels unnatural.
The only practical risk on the way to the surface is having a lungful of air at 20m ambient pressure, which will expand as you ascend, and could cause a simple pressure trauma if you held your breath. You'd need to breathe out constantly as you went up, to let the expanding air vent off. Breathing out underwater feels unnatural.
That's quite true for a snorkel dive, I don't think there are too many people that can hold their breath for 70+ minutes at 10feet under water to decompress :) (never mind the staying under for 200 min :))
I never found it a problem breathing out when surfacing, I don't really see why people have a problem with it, to me it always seemed to be the only thing you can do!
I really should get the gear out again, I used to love going on diving holidays down off the Cornish coast.
I never found it a problem breathing out when surfacing, I don't really see why people have a problem with it, to me it always seemed to be the only thing you can do!
I really should get the gear out again, I used to love going on diving holidays down off the Cornish coast.