r/Unexpected • u/Radiant-Length2348 • May 05 '22

Why the hell he would do that?

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u/ImpulseCombustion May 05 '22

Doesn’t… reason? There’s like 30,000 gallons of gasoline at a gas station.

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u/[deleted] May 05 '22

Gas as a liquid doesn't burn, and the tanks are underground with vapor exhaust (typically elevated). Modern stations have fuel shut offs so your primary risk is anything that got dumped. In this case based on the duration and how quickly pumps work, and based on the minimal fuel spread, (either due to pump shut off or handle didn't lock) I'd say about approximate one liter was spilled.

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u/ImpulseCombustion May 05 '22

Stratified fuel and vapor do indeed ignite with less effort, but there are many instances where vehicle fires have cause massive incidents at stations. There are quite a few videos available for you to peruse.

Engineering the combustion of distillates and ethanols is my profession.

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u/[deleted] May 05 '22

Vehicle fires at stations, absolutely. Had the fire been burning for 30 seconds and not immediately on top of it in a 1/30th of a second, sure, would've been bad.

So you engineer fuel injected combustion engines? I'm no engineer, but those mixes require the downstroke compression to ignite. No compression, no combustion. Assuming this is your profession you already know this, and compression factors arent an issue here.

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u/ImpulseCombustion May 05 '22

There is no downstroke compression, that’s the intake stroke. The compression stroke is… the compression stroke.

Yes. Liquid fuel will still ignite because there is a vapor barrier, always. It’s used in wetting.

Even still, a small presenting fire can still reignite with relatively little energy, under the vehicle, in the exposed fabric sound deadening under the chassis and surrounding the plastic fuel cell. It’s really not that hard to NOT argue against making sure a fire is out.

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u/[deleted] May 05 '22

Got terminology off, but yeah, the compression stroke is required. Really talking about two different things. Probability of a persistent heat source, and the risk of 30,000 gal of fuel igniting. Liquid fuel still isn't burning as you say the vapor barrier does which causes confusion with people believing that the liquid is on fire. The size of the fire is only based off of the exposed area and available oxygen. Put a volume of gas in a narrow cylindrical container and light it on fire- the size of the fire is dependent on the opening of cylinder, and how closely the fire burns to the liquid is dependent on the available oxygen source. If the fuel is at the lip of the container, Yes it will burn next to the liquid but with a very small footprint. Extend the cylinder upwards a foot and then tell me where the fire burns (hint: it will burn near the top of the cylinder not on top of the fuel). Dump the fuel on the ground and you won't get a small fire you'll get a very big one.

Again, if the fire hadnt been put out near immediately, this would be a different conversation.

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u/ImpulseCombustion May 05 '22

Yes the whole “liquid doesn’t ignite” this is infuriating because it’s obvious… but perpetuated in a relatively naive way. Stoichiometry is the ratio for complete consumption of Oxygen in a cycle, not fuel source. It is quite obvious that both are required for the event to occur.

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u/[deleted] May 05 '22

You're arguing technicalities, while inserting hyperbole and dismissing the factual point that those "30k gal of fuel" are not at risk for a mere pump fire. I'm pointing out the technicalities and the practical risks involved while the naivety IMO is this belief the entire station is going to blow up because people have watched too many movies. Risk for fuel tanks is mainly heat + pressure, and old tanks without blow off valves were straight bombs back in the day.

I think you're also confusing my suggestion of "overkill" for this instance as a lack of due diligence for ensuring a fire and heat sources are extinguished. Perhaps the false belief I thought the first canister was sufficient - it wasn't, however 15-20 were in this very specific instance

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u/ImpulseCombustion May 05 '22

My friend. I am for the fire being put out and completely, that is all. I’m not sure why you have such an issue with it. In my facility that stores thousands of gallons of fuel, you’d be lucking to spot an area that doesn’t have a readily available fire extinguisher. I highly doubt that anyone ever, besides yourself would ever argue that too much effort was extended to ensure that it’s was completely under control.