So I understand chemical bombs (as opposed to nuclear bombs) contain their own oxidizers for combustion. If this is always the case (which I believe it is, but I’m not certain), would the amount of oxygen in the surrounding air make a difference regarding the size or speed of the explosion? I’ve been wondering this since seeing an episode of Grey’s Anatomy (my cousin recommended I watch it) where a homemade bomb was embedded in some guy’s chest and they had to remove it. They moved the guy out of the operating room he was in because it had oxygen lines running under it, and they said it could cause the bomb to blow up the entire hospital instead of just a room. Obviously tv shows often mess up things like this, but I wanted to make sure. Ambient oxygen content would have no effect on a bomb’s explosion, right? I’ll contest that it could worsen fires caused by the explosion, but the initial explosion would be the same, right?
Just a guess here, but if the oxygen lines are under pressure and begin to rupture, then you could get an explosion due to the quick release and expansion of the gas, not really from the bomb itself.
That might be true, but I couldn’t imagine the entire hospital blowing up due to that.
I’m not a chemist nor even an explosives specialist but I think the show was exaggerating. In order for oxygen to cause combustion it has to have something to oxidize. Things like oil and stuff like that are quite hazardous around oxygen. In places where oxygen equipment is used the standard procedure is to limit the amount of combustibles if possible. In addition, in order for an explosion to be really bad the combustion must be confined in order to build up a high pressure. This increases the rate of combustion and when the pressure is released suddenly, as when the bomb case finally ruptures, creates a high pressure shock wave that does the damage.
In an oxygen atmosphere a bomb might very well cause a big fire but I question the story about a big explosion other than the oxygen tanks themselves rupturing asRaftPeople said.
Not necessarily. See the Mythbusters shark week episode; they shoot through a scuba tank; it does not explode. (Yes, I know that O2 tanks are not scuba tanks, but I am willing to bet on them not exploding.) However, in that same episode, an explosives expert for the FBI attaches some explosive to a tank, and mentions that the tank will act to potentiate the explosive. The only thing that I can think of is that, although the high explosive will contain oxidizing agents (it does not have to be oxygen itself), the presence of a high concentration of readily available O2 will serve to speed up the reaction. It could also be that the O2 is in a form that is much more “active” in air, as opposed to the form it is in in the HE.
Do I think the entire hospital would blow up? Of course not. But the O2 would add extra oomph to the explosion.
Exactly right. In solid and liquid explosives, the reaction is over far too fast for the ambient oxygen to be involved. Gas, aerosol and dust explosions are a different matter.
On the other hand, if there was a compressed oxygen cylinder nearby, it would probably be wise not to have a bomb going off near it!
As a matter of interest, not all explosives are “oxygen balanced”. TNT is oxygen poor, and will leave a cloud of uncombusted soot after exploding. I’ve read that this cloud can cause a secondary dust explosion if TNT is used in an enclosed space e.g. in a mine, but I have no cite.
And extra oomph to the subsequent fire. Such a fire is fairly likely after an explosion, and the extra oxygen from the burst piping, would certainly feed the fire for a while.
Thermobaric weapons use oxygen from the surrounding air instead of an oxidiser in the bomb itself.
Indeed, but they still have to mix with the air to create the explosive cloud; the fuel-air mix constitutes the “body” of the explosive. When detonated, the oxygen in the air “outside” the mixed cloud doesn’t contribute to the immediate explosion, any more than the air outside a condensed explosive does. The air outside the cloud would play a role in the secondary effects, and a thermobaric bomb in an oxygen atmosphere would be rather feisty! Not that you’d have a homemade thermobaric bomb embedded in someone’s chest anyway. True fuel-air detonations are actually rather difficult to create in the open with liquid fuels, and rather too easy to create in enclosed spaces with fine flammable solids. Sugar mills face some significant explosive hazards.
as stated above, the explosion itsself would not benefit in any appreciable way from marginally enriched atmospheric oxygen levels; the explosion itsself is simply too fast in its combustion. However if the explosion ruptured the O2 supply lines coming form the house oxygen supply you could very possibly have a runaway oxygen supported fire that would burn damn near anything nearby. And I do mean anything; even steel. Typically hospitals have large liquid O2 tanks outside, and they vaporize the LOX and pipe it throughout the hospital. I do not know the details on emergency shutoffs for the house O2 systems, but there are provisions for isolating sections of piping at the very least for ease of maintenance, let alone for emergency purposes.
Agree with krisolov. All sorts of things that don’t normally burn will burn gangbusters in an elevated oxygen environment.
As do flour mills and grain elevators.
Interesting. I knew it was possible for certain dusts and vapors to explode in air, but I didn’t know they had made a bomb that uses that effect. While that probably couldn’t explain the tv show, it does partly answer my question.
So chemical bombs other than thermobaric bombs could explode in a complete vacuum, right, assuming it didn’t have a burning fuse? Now that I think about it, they can explode under water, so I suppose they could in a vacuum.
A survival test my Dad had at work (multiple choice on a paper, it was the bank after all, not the Royal Marines 
) asked what you could bring along on a Moon walk to help. A pair of guns was thrown into a list from which you could only take a few items. The guns were useful for propelling you along the Moon’s surface, you pointed them down at an angle and fired, the recoil propelling you along to save your energy. I’m sure working out a gun powerful enough to do this is for another thread
Speaking of the Moon, the OP did make me think of the unfortunate fate of the astronauts of Apollo 1 a horribly grizzly death 
Actually that just sparked my memory, either in that episode or on some other show about diving, they talked about and showed the results of O2 tanks rupturing and exploding.
In one case there was a weakness in the metal, and if I remember correctly the person lost his leg, arm, hand or foot (something).
The myth busting they did was more related to a gun making it explode, which it didn’t, but they did not test anything that caused a larger rupture in the cylinder.
So yes, oxygen under pressure without anything flammable can indeed cause a significant explosion under the right circumstances.
Divers normally use compressed air, not O2. I would expect that the rupture of a tank of compressed gas at 2000 psi, no matter what gas, is going to cause serious damage.
I’ve seen pictures of old-style steel SCUBA tanks where water condensation had caused corrosion and dangerous weakening of the bottom of the tank.
Oxygen tanks (and all other compressed gas cylinders) are periodically hydrostatically tested every 5 or 10 years to insure the metal has not fatigued to the point where they are unsafe to refill. Very rarely these cylinders will fail catastrophically. When they do, they tend to split/open up, rather than shatter. I am pretty sure the steel used in theor manufacture is specifically selected for this purpose. This was evidenced in the Mythbusters episode where they were trying to detonate a scuba tank. It took explosives to open one up, and even then there was little fragmentation from its catastrophic failure.
That’s good to know. If I ever got stranded on the moon, I’d hate to have to carry my own 30 pounds around. I probably couldn’t walk 50 feet before getting exhausted.
Thanks for the answers guys. I knew that show had made a faux pas; I just needed someone to agree with me.
I beg to differ. I remember specifically that the FBI explosives expert was present, and used the facilities and opportunity to show an IED. In doing so, he mentioned that the compressed air tank potentiated the explosion. Although, to be fair, I could not in all honesty say that the effect was from the presence of a higher concentration of oxygen or simply from the tank being under pressure.
The idea of “bringing your own oxidizer along” is the reason that solid-fuel rockets work in space. If the rocket motor casing ruptures or gets a hole somewhere other than the nozzle, it will explode plenty. There are a few minor differences in how it would burn, but your average Joe on the street would have a hard time differentiating between a rocket motor and a bomb going off in a vacuum.