What air pressure can the human body survive?

[fawk3s]

so on low pressures you can breath 100% oxygen without any damage?
then how much do airplanes use in their tanks, you know, those for the passengers in case of an accident?

 

[DaveC426913]

so on low pressures you can breath 100% oxygen without any damage?

This is what they planned to do with the early Apollo missions. But they found it to be a http://en.wikipedia.org/wiki/Apollo_1#Incident"...

 

[mgb_phys]

so on low pressures you can breath 100% oxygen without any damage? then how much do airplanes use in their tanks, you know, those for the passengers in case of an accident?

You can breath pure oxygen at 0.21 atmospheres and receive the same oxygen as normal air. This is what the Mercury and Gemini spacecraft used.
This has the big advantage that in space the pressure on the hull is only 0.2atm (3psi instead of 15psi) it also saves weight and removes the risk of decompression sickness if you have to escape at altitude. 0.2 atm of pure O2 is not a fire risk.

The fire on Apollo 1 was caused by an amazingly dumb mistake in a test. The craft was designed to operate at 0.2atm pure oxygen in space, to test the doors on the ground they needed the inside to be 0.2atm higher pressure than outside. They did this by filling it with 1.2atm of pure oxygen which is an incredible fire risk - rather than keeping 0.2 atm of oxygen and adding 1atm of nitrogen/helium/or just about anything else.

Large commercial aircraft carry 100% oxygen but their cabin operates at around 0.75atm air pressure. Smaller aircraft often use 80% oxygen cylinders because with 100% O2 you have to be very careful about the type of grease, rubber, plastic etc used - 80% O2 is much safer.

 

[DaveC426913]

The fire on Apollo 1 was caused by an amazingly dumb mistake in a test. The craft was designed to operate at 0.2atm pure oxygen in space, to test the doors on the ground they needed the inside to be 0.2atm higher pressure than outside. They did this by filling it with 1.2atm of pure oxygen...

Yes. I never knew this until I read that Wiki article just now. The story I've always known was a simplification of the facts - no mention that it was a test, and no mention that they overpressured it.

 

[DaveC426913]

Let me fix it first.

Since your PM box is full, I cannot be discreet and am forced publicly bug you to send me your novel.

 

[xxChrisxx]

Yes. I never knew this until I read that Wiki article just now. The story I've always known was a simplification of the facts - no mention that it was a test, and no mention that they overpressured it.

Whats more shocking is that the saftey feature of an inwards opening hatch suggested/demanded by Grissom is what killed* the crew.

EDIT: *Contributed to killing them, no one aspect of the accident was directly responsible but the combination was fatal.