Mini O2 Tanks

Question
I was reading a previous question in which a woman asked about the Mini O2 Tanks you commonly see in movies. I do understand the need for you to be careful with the info you provide. And in her question you never really gave an answer. My interest isn't for the personal usage she wanted in the mini tanks, but rather a safety feature in my vehicle. Do they make these mini tanks for people to store in a vehicle in case, by some chance, they're in an accident/situation where they find themselves underwater?

Answer
Hi Bobby, that is an interesting question.  I don't really know know if they make them for that specific reason.  I don't have much access to accident statistics to even evaluate the likelihood of such events (as compared to other severe life-threatening accidents).  Since you brought it up however, you must feel some concern about the possibility so let us consider your request as met with a SCUBA cylinder and regulator.

A popular SCUBA cylinder company makes cylinders that hold as little as 6 or 13 cubic feet of air.  I mention these because the size would at least be reasonable to carry inside a vehicle.  That size cylinder would give you around 10 to 18 minutes of air time respectively.  You would also have to have a regulator already attached to the cylinder to be able to breath from it; and, be in a condition that you could turn on the gas, put the regulator in your mouth and breath from it.

There are numerous considerations.

1) mounting the tank in such a manner that it does not become a projectile and hurt you or passengers in the vehicle in the event of any kind of crash; yet still remain accessible after the crash
2) what about passengers in the vehicle with you; do they get any?
3) storing compressed air in a vehicle is extremely unwise as the temperatures in a parked vehicle in the sun could get hot enough expand the gas past the load limits of the cylinder resulting in an serious explosion risk.
4) filling the cylinder would likely require a SCUBA certificate from one of the agencies
5) training is recommended any time you plan to breath compressed gas underwater
6) costs compared to likelihood.  A small cylinder and regulator would set you back about $350 - $500.  You must also have the cylinder emptied and visually inspected each year by a professional (about $25, plus another air fill); and every 5 years a hydrostatic test is required (about $35, plus another visual and another air fill).  The regulator (1st and 2nd stage) also require annual inspections at around $25 to $45 per stage.
7) you may also wish to consider the likelihood of even being able to retrieve the device after this kind of accident (for instance if you were unconscious or the vehicle severely damaged).

Hopefully this helps in your decision making.  As a SCUBA professional, I would not recommend this course of action especially in light of #3 above.  Jesse