Re: OT news article

Ok so the explosion was caused by breathing apparatus not fuel vapour.

In such areas, explosions due to pressure vessels bursting or imploding are common.

Joe

Put some Mentos in a bottle of soda...

Sure. I remember watching a video of someone putting a bottle of beer in a microwave oven out in the open away from buildings and then arranging for the microwave to run on full power. I forget how many minutes it took before the microwave oven was obliterated. Not the kind of thing you expect to happen in a fuel tank.

Aircraft fuel tanks are sometimes fitted with explosion suppression systems. These have a tank of fire extinguishing fluid pressurised with nitrogen. A thin "bursting diaphragm" keeps it all in the cylinder until a fire or explosion is detected at which point a small explosive charge ruptures the diaphragm releasing the fire suppressant faster than the flame velocity in the original explosion.

I once applied for a job at a company which made such systems. I decided not to follow it up when I discovered how the vacancy had arisen.

John

There are other sorts of explosion in some high energy materials.

Most notably an entropic explosion where the molecule just literally falls apart with a rapid increase in volume. TATP is a canonical example

Perhaps by accidentally setting off the fire control system that is intended to quench flames if the fuel tank is ruptured.

If it had been a proper fuel vapour and air explosion then the wing would have been totally destroyed. Whatever happened was lethal to humans at close range but not to the airframe.

In some industrial chemical tanks with highly flammable contents they purge continuously with dry nitrogen and require workers to wear normal air sets (to minimise risk of having a detonation from residual fumes). And they use tools made of beryllium copper that do not spark.

Mix the wrong chemicals - sudden release of gas or steam.

Sudden release of pressure or vacuum (implosive).

An electrical fusing event - melting of metal conductor.

Not all 'fuels' will combust by themselves - they need to combine with something else (eg oxygen) and/or be triggered.

RL

Looking at the 787 firefighting manual, I'm not seeing any fire bottles inside the fuel tanks. The cargo and engine fire bottles are further forward (p197):

I was responsible for overseeing the production of an "explosion proof" computer used on the (military) flight line. It was disconcerting to worry that you might overlook some detail and, at some future date, someone might lose their life in a fire/explosion because of that omission!

Most distressing was the knowledge that you'd never KNOW that you'd done the job correctly!

Most explosives produce non-combustion explosions.

The interesting variant is mono-propellant rocket fuels.

My post-doc project was supposed to look at compound - Dewar benzene - which would qualify.

What the original observer hadn't been aware of was that the isomersation released enough energy to heat the molecule to about 2000K

- white heat - and the flash of light was just thermal radiation, and not in the least photochemically interesting.

It would have made a nice mono-propellant if it hadn't been exceedingly expensive to make.

Maybe the second reason it didn't go anywhere?

RL

No. It was commercially available in the very small quantities we would have used. I was thinking of picking up a very low concentration of the molecules in a stream of helium then warming them up enough to get enough isomerisations to see - with a photomultiplier as your emission detector, you can count individual photons in the visible range.

Near-infra-red photons are harder to pick up.

Overpressure, as in a steam boiler exploding.

Cheers

Phil Hobbs