How much oxygen is there...

SideWinder · 27 Dec 2010 at 02:04

Inspiration = That James Bond film where James has that tiny thing on his mouth that means he can be under water for a while.

In a standard scuba diving tank, how much oxygen is there? How much could Bond's hold in theory?

Yes i can't sleep.

Greenlizard0 · 27 Dec 2010 at 02:10

I think there was a thread (possibly here?) a while back where they theorised about 'drowning' somebody in a very oxygen rich solution. Therefore the diver could be underwater for longer, dive deeper and because nitrogen respiration didn't occur there was less chance of getting the bends.

Zefan · 27 Dec 2010 at 02:21

It's not Oxygen, it's just compressed air so roughly 20% Oxygen, 80% Nitrogen.

The actual amount of air stored in the tank depends on the size, roughly 12-15L, and how much it's pressurised. Also, the depth at which you'll be diving - the deeper you go, the more air you use.

Same principle applies for Bond's gadget!

Sinny · 27 Dec 2010 at 02:22

As above, just compressed air.

Horrible, I hated it when I went Scuba diving, leaves your mouth dry.

Energize · 27 Dec 2010 at 03:08

Just compressed air? That seems incredibly inefficient, the nitrogen could be reused continuously and CO2 removed providing a much larger capacity.

EniGmA1981 · 27 Dec 2010 at 06:50

oxygenated water is what you want, like on the Abyss... funky pink liquid that lets you dive down about 3 miles lol

Didn't look comfortable breathing it in though

DampCat · 27 Dec 2010 at 06:56

Energize said:
Just compressed air? That seems incredibly inefficient, the nitrogen could be reused continuously and CO2 removed providing a much larger capacity.

These exist, they're called Rebreathers. They're closed loop systems (ie, you wont see any bubbles flowing up from a diver using one... although they still add them in in movies) and have hoses attached directly to full-face masks. These are the ones that allow you to talk as there's nothing in your mouth.

They're not really necessary for recreational diving, as a tank of compressed air will last you the best part of an hour, plus a regular tank's displacement/weight is instrumental to buoyancy, so reducing the size of it would only require you to have heavier weight belts/larger BCD. Rebreathers are used for tech diving, rescue diving and commerical diving, though. Or even recreational diving in dry suits, such as ice diving etc.

DampCat · 27 Dec 2010 at 07:06

The tiny thing that sits in his mouth might be enough for half a lungful of air :/

You can get a Pony, though, which are used in emergencies. They're the size of a tiny fire extinguisher (like those desk sized ones, you know?) and are usually enough to resurface, or at the very least get to your buddy's Octopus (secondary regulator, usually yellow).

I dunno. I'm kinda guessing at the half a lungful thing.

Cosimo · 27 Dec 2010 at 07:59

Milkybk said:
I always thought there was more oxygen in them than normal air..

For normal dives: compressed air - 78% nitrogen, 22% oxygen

Long and repeat dives: Nitros - oxygen increased to 32% or 36%

Deep see diving: Trimix - 10% oxygen, 70% helium, 20% nitrogen

Efour · 27 Dec 2010 at 08:05

I watched a documentary about deep sea divers working on a pipeline or Platform, 3/4s o fit was like watching a Disney cartoon because of all the ludicrous high pitched voices caused by their mix, quite funny especially the dinner time scene, a Skinhead bruiser of a guy with a Glaswegian accent talking like Mickey mouse :O

tigerstyle · 27 Dec 2010 at 08:35

SideWinder said:
Inspiration = That James Bond film where James has that tiny thing on his mouth (

liar, you mean baywatch really don't you?

Fuzz · 27 Dec 2010 at 08:58

Energize said:
Just compressed air? That seems incredibly inefficient, the nitrogen could be reused continuously and CO2 removed providing a much larger capacity.

That's called a rebreather.

Fuzz · 27 Dec 2010 at 09:00

DampCat said:
These exist, they're called Rebreathers. They're closed loop systems (ie, you wont see any bubbles flowing up from a diver using one... although they still add them in in movies) and have hoses attached directly to full-face masks. These are the ones that allow you to talk as there's nothing in your mouth.

They're not really necessary for recreational diving, as a tank of compressed air will last you the best part of an hour, plus a regular tank's displacement/weight is instrumental to buoyancy, so reducing the size of it would only require you to have heavier weight belts/larger BCD. Rebreathers are used for tech diving, rescue diving and commerical diving, though. Or even recreational diving in dry suits, such as ice diving etc.

Rebreathers don't specifically have full face masks, you can have one on open circuit diving equipment as well. Certainly a good idea in cold water environments as it keeps your face warm

Zip · 27 Dec 2010 at 09:03

EniGmA1981 said:
oxygenated water is what you want, like on the Abyss... funky pink liquid that lets you dive down about 3 miles lol

Didn't look comfortable breathing it in though

Ive always wondered if that is a really a real way of diving or just made up :confused:

Fuzz · 27 Dec 2010 at 09:14

Oxygen itself starts to become toxic the deeper you go. There's a whole host of other issues you have to think about too.
I'm going to have to get the books out if I am going to go into it to any depth as I've forgotten most of it.

Basically the recommended safe limit of ingested oxygen is 1.6ppo (partial pressure oxygen) about eight times the normal pressure
or you'll pass out. Passing out under water is bad M'kay.

Fuzz · 27 Dec 2010 at 09:16

Zip said:
Ive always wondered if that is a really a real way of diving or just made up

Made up. The human body doesn't have the ability to respirate a liquid

Baz · 27 Dec 2010 at 09:18

Milkybk said:
I always thought there was more oxygen in them than normal air..

There can be as said with Nitrox, issue then becomes that the partial pressure of oxygen increases and can become dangerous below certain depths.. EAN32 is somewhere around 36-38meters.

Pure oxygen would kill you at about 5-6 meters :eek:

Nitrox is used to prevent the build up of Nitrogen in the body tissues, which gives you a greater safety margin for repeat dives from DCI.

Baz · 27 Dec 2010 at 09:20

Scubascorpion said:
Oxygen itself starts to become toxic the deeper you go. There's a whole host of other issues you have to think about too.
I'm going to have to get the books out if I am going to go into it to any depth as I've forgotten most of it.
Basically the recommended safe limit of ingested oxygen is 1.6ppo (partial pressure oxygen)
or you'll pass out. Passing out under water is bad M'kay.

Or just convulse and die very quickly... The Nitrox course is quite scary

semi-pro waster · 27 Dec 2010 at 09:26

Scubascorpion said:
Made up. The human body doesn't have the ability to respirate a liquid

I'm not sure that experiments have ever been done on humans to test this though, there are certainly some that have been tested on other mammals such as mice and they can breathe in liquids for a time but will usually die of pulmonary or respiratory problems relatively shortly afterwards (assuming they survive the initial dunking). So at the moment it looks unlikely you could utilise liquid breathing, at least for diving, but who knows what future advances may bring.