The non-wiki article.
http://www.bp.com/content/dam/bp-cou...icle-tanks.pdf
The non-wiki article.
http://www.bp.com/content/dam/bp-cou...icle-tanks.pdf
we may just go where no ones been
That's actually a very good article for the lay person. Cmon phil up your game.Not that I can see him posting something from BP.
Don't you look at my accountant.
He's the only one I've got.
Fuck
My bread is stale.
Nunquam Non Paratus
That BP article touched on the basics. Fuel either goes stale, or loses it's light ends - this is two different processes.
Fuel left in a tank and exposed to air will oxidise, this will cause the molecules to join together and form gums and varnishes. But this is a process which happens slowly. Using something like an additised petrol (and the premium fuels are more likely to contain an additive) should clean carburettors, injectors and the back of inlet valves of deposits and give easier starting and smoother running.
Loss of the petrol's light ends is another matter, this can happen quickly. Petrol contains a range of hydrocarbon molecules from butane (C4H10) through and beyond molecules around C10, and including aromatics (fairly volatile). The more volatile molecules contribute to the petrol's starting characteristics, they evaporate easily and ignite. Winter petrol will have higher volatility (measured as Reid Vapour Pressure) than summer petrol, so something bought in winter and put into the tank in summer may give noticeable differences in starting. These more volatile compounds, the light ends, evaporate naturally, so the petrol loses it's ability to evaporate on starting. A petrol which is missing it's light ends is called "topped". Once started and the engine warmed up there is less problem with a topped petrol, the heavier ends evaporate anyway and the engine appears more powerful.
Apparently petrol stations are fitted with means to reduce this happening in tank by means of providing pressure with a tall curved vent, but I've yet to espy one.
Don't you look at my accountant.
He's the only one I've got.
Think their prob all straight these days with relief valve installed. In the right lighting conditions you can still see the vapours pouring out the top.
Back in my younger days when I was a Petroleum Dispensary Technician aka attendant I think the tanks typically lost 2% by volume due to evaporation, can't remember if it was daily or weekly...
Every great cause begins as a movement, becomes a business, and eventually degenerates into a racket - Eric Hoffer
Depends really how important performance is to you
You're kinda overthinking the subject. A tall vent stack combined with the fact that concentrated fuel vapour is still heavier than air means that the only time you get significant amounts of vapour coming out is during a delivery via road tanker. Temperature fluctuations play a very minor part, and let's face it, most servos get at least one delivery a week...so stale fuel at a servo is more or less a non event.
And no I'm not especially qualified, having spent only 15 or so years as a Petroleum Products Transportation Technician, so I'll admit to being almost entirely clueless on the subject![]()
And yet I'm still picking Phil as my go to engineer on the subject
Don't you look at my accountant.
He's the only one I've got.
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