Listen Up Young & Old

I'm sorry to hear about your friend. With your experience do you have or know of a cap that doesn't leak, even a bit ? Both my bike and my wifes have a bit of fuel mixture around the cap and on the tank that we wipe off constantly to keep the paint looking good for as long as we can. It's not alot, just a bit, enough to be annoying ! I think we tried everything we could think of. Thanks in advance.

duely noted thanks for the tip

Saddletramp1200 said:

The gas tank blew and severely damaged several of his vital organs. He lived less than 24 hours. He had wraped black tape around a leaking fuel line.

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As a safety team leader at a steel service center, I understand the importance of talking about safety issues and communication, however it goes a little far when someone exaggerates an accident.

You do realize that gasoline is only flammable and not "explosive". So would you like to tell us all how a gas tank catching fire damages vital organs, unless of course it was the guys eye balls?

Me thinks you have watched one too many episodes of the A-team where Hollywood makes gasoline tanks explode as if it was loaded with Composition 4 explosives.

UVsaturated said:

As a safety team leader at a steel service center, I understand the importance of talking about safety issues and communication, however it goes a little far when someone exaggerates an accident.

You do realize that gasoline is only flammable and not "explosive". So would you like to tell us all how a gas tank catching fire damages vital organs, unless of course it was the guys eye balls?

Me thinks you have watched one too many episodes of the A-team where Hollywood makes gasoline tanks explode as if it was loaded with Composition 4 explosives.

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I know I'm certainly scared right now! Esp. since the cap on my real motorcycle won't even stay locked down, just sort of lays there with me hoping it stays put... I gotta look into replacing that thing!

UVsaturated said:

You do realize that gasoline is only flammable and not "explosive". So would you like to tell us all how a gas tank catching fire damages vital organs, unless of course it was the guys eye balls?

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Actually, if you accumulate a large quantity of gas vapor in a contained area, at a perfect 14:1 ratio with oxygen, it will indeed explode quite readily if given an ignition source.
But your point is very valid...typically gasoline is in a way too rich environment, allowing only a portion of it to burn at a time. Very little danger at all throwing a match into a bucket of gas, at least until it melts and the liquid fire then spreads everywhere!

cityevader said:

Actually, if you accumulate a large quantity of gas vapor in a contained area, at a perfect 14:1 ratio with oxygen, it will indeed explode quite readily if given an ignition source.
But your point is very valid...typically gasoline is in a way too rich environment, allowing only a portion of it to burn at a time. Very little danger at all throwing a match into a bucket of gas, at least until it melts and the liquid fire then spreads everywhere!

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I think I'm gonna try that!

Be right back....

Some of you might remember the gas embargo in the seventies. People had a habit then of carrying a spare gallon of gas in the trunk of the car. At that time I was a member of the local pd.

We had a film of a car's "spare" gallon exploding in the trunk. The way the atf boys made it blow was not with c4 at all. They sat the junk car in the parking lot of a closed plant. The put 3/4 of a gallon of gasoline into a gallon metal container/ they left it in the sun most of the day. At 3pm they used a spark igniter only to fire the fumes. It blew the trunk lid off the car. Gasoline will explode if the circumstances are just right. I have never done it thank god, but I have no doubt that a half filled gas tank will create the right inviornment for an explosion. I call your attention to the airplane the blew up off the northeast coast of the usa a couple of years ago. A spark in a gas tank filled with fumes brought it down.

I believe you are riding around with half a stick of dynamite between your legs.

deacon said:

I believe you are riding around with half a stick of dynamite between your legs.

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If it were anywhere nearly like that, farmers would have used gasoline to blow stumps out of the ground instead of dynamite.

The perfect fuel to air ratio will allow gasoline fumes to burn at its most rapid rate, however that is no where near the rate of expansion that a pressure wave off a stick of dynamite propagates.

You also have to remember that you have to have all that air inside a gas tank for it to be at just the right ratio to burn this way, which is normally not the case with a closed gas tank.

I've seen plenty of auto races where cars have caught fire, some of them in classes without fuel cells containing foam cores and they do not explode, they just burn like crazy. If there ever was a perfect environment for a gas tank to explode, it would have been all the times I've seen cars burn down to nothing on those occasions. Not once did I ever see any of them explode. Exploding fuel tanks are a movie illusion, not something that happens the way it is depicted.

Actually there is quite a bit of truth in what deacon says. One gallon of gasoline, given the proper conditions has the same explosive potential as one stick of dynamite, but... a full tank really has no chance of exploding. Although a nearly empty tank could go off like a small grenade.

Gas tanks can explode, I have seen a tank on a small dirt bike explode, fortunately no one was on or near the bike at the time it went off, but it certainly left an impression on me.

Hollywood does over do things, and the chances of an explosion are rare, like getting struck by lightning, but the chances of getting severely injured does exist if the fuel system on anything that we have to be so closely situated to has some sort of a problem. (Pour a little gas down your pants leg and light it. You might find it difficult to have it extinguished before you'd like. (Actually, please don't pour the gas down your leg.))

Saddletramp1200 is bringing up a good point here, and I've known many to just patch or ignore a fuel system problem, that's not the best course, maintain and repair your fuel system correctly, not only for safety purposes, but it will eliminate other problems as well.

My chemistry-minded approach from school has impressed me to do many calculations.

Molecular units (moles) are the standard measurment. A mole of oxygen weighs 32 grams, and a mole of gasoline weighs 114 grams. And a pound of oxygen at 1 atmosphere pressure (sea level) is about 90 gallons in volume. A pound of gasoline is about .1666gallons.

With the perfect air/fuel ratio of 14.7:1 (by WEIGHT) to have the most rapid and complete combustion (explosion) with 1 gallon of gasoline we would need 2,226 gallons of PURE oxygen. But the Earth's atmosphere is 21% oxygen, so we'd need about 10,600 gallons of typical "air" that is all around us, in order to "explode" 1 gallon of gasoline.

That is assuming that the liquid gasoline is perfectly vaporized into gaseous form along with the gaseous oxygen. There is nothing close to these proportions on the highways and byways that I'm aware of. Do you have a motorbike with an 10,600 gallon fuel tank with one gallon of vaporized gasoline in it? Do you have a car or truck or bus or airplane with that?

Of course, you can still have smaller explosions within a 1 gallon gas tank, but there would have to be .000094 gallons of gasoline to the remainder of atmospheric air to have the proper air/fuel ratio. Fortunately, inside of gas tanks there is WAAAAYYYYY more fuel than air, so it cannot possibly explode, but only burn (if left continually exposed to after after the ignition required).

There is no way I take risks with anything when dealing with petrol but I have had some close shaves - not related to bikes though so maybe a little off topic - if so I apologise...

First was with my old humber - myself, my partner and her daughter are in the car and coming off a roundabout - the engine starts to sound weird, not much, just a little off (I have a good mechanical ear...). Then all **** breaks loose and the motor starts to sound like a B-17 after a bad week. Its pitch dark and freezing so I stop, get out and pop the bonnet with the motor idling and see this little blue flickering light... I got my partner to switch off and I investigated... to find the engine had thrown out number 1 plug which was happily twinkling away sans the rest of the engine. I gingerly replaced it by touch (can you say burnt fingers...) restarted and continued on...

It was only in the morning when I checked again that I found that the plug had landed on the plastic fuel-line downstream of the fuel pump and almost incinerated the three of us. The scary thing was there was no way we could have gotten the baby out in time if it had gone up - she was securely trussed up in a child seat

The next time was at a classic car rally when a guy pulled up next to us in a mint Snipe 80 - and a miasma of neat petrol fumes - his steel fuel line to the carb had fractured and was spraying neat petrol onto the exhaust manifold... he'd been smelling petrol for 20 miles and hadnt bothered to investigate. Took four of us an hour to cobble a fix together so he could get home.

NEVER, EVER take a risk with petrol or any other inflammable chemical - I have even seen burns from someone throwing home made mead on a fire as part of a winters night celebration - the stuff practically exploded!!

As an MB aside - as regards safety the chengines and similar with a separate fuel tank are better on safety as you arent pouring petrol right next to a possible hot engine... GEBE owners beware...

Safe journey

Jemma xx

this might turn into an emotional issue. I have always heard that a full gas tank will not burn or explode but one with a few drops in it will. Unless someone explains why all those government tests I have seen were the result of hollywood C4, I'm gonna fix my fuel leaks and be careful with my gas tank.

deacon said:

this might turn into an emotional issue. I have always heard that a full gas tank will not burn or explode but one with a few drops in it will. Unless someone explains why all those government tests I have seen were the result of hollywood C4, I'm gonna fix my fuel leaks and be careful with my gas tank.

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Perfectly said.
We all agree gas is bad bad bad when uncontrolled, and absolutely more than mere common sense should be used around it.
Especially if you have an "empty" tank and are blowing it out, right next to an ignition source, as this would be the ideal time for for an explosion.

The safety points here are well taken. I'm not riding anymore until I fix my leaking cap.

A crotchful of gas is a terrible thing to lose.

A full tank of fuel lit from the filler neck will burn - if you are insane enough to try it. The reason it burns and doesnt go up and take the garage with it is because in order for petrol to burn at all it needs to vaporise at the flash point.

In a motor there are two ratios that are important - mixture and compression. the stoichiometric pressure for petrol is 14.1:1, ie a compression ratio of 14.1:1 will give you the maximum power release - however this is hard to obtain and requires high pressure injection systems so most engine designers tend to go the easy way and go for a medium high compression (around 10-11:1) and increase the rpms using such tricks as desmo valves or pneumatic valve springs (formula 1). The other method is increasing the swept displacement by boring out and fitting oversize pistons and hardware. In the case of the Rootes group 1725cc engine a compression of 9.7:1 and rebore giving 1800cc is possible which gives up to another 10hp or so

Then there is the matter of mixture. In order for any fuel to burn it needs to be mixed with the right amount of oxidant - in this case oxygen from the air. Too lean and the mixture burns hot, you get cooked plugs and if left too long valves and general overheating. Too rich and you get a cold burn which in older engines caused coking up and that blackish smoke when throttled. Both of these conditions reduce the power of the flash burn and therefore engine power.

Now, if you have a petrol tank on your MB and you leave the machine in the open in the sun you will notice that if you open the cap (if unvented) you will hear a hiss and smell fuel. What you have in that situation is both a degree of compression and a fuel air mixture... and its this that is the explosive combination.

It is a myth that only an almost empty fuel tank is the only one that will explode, it merely means that when it does go up you get the most bang for your buck as it were and it does the most damage to anything in its immediate surroundings. As long as there is petrol vapour in air there will be some sort of explosive reaction - it is merely how much fuel/air mix that controls how bad the bang will be.

If you have seen aircraft in films that are on fire for whatever reason you will notice that alot of the time at first the fire seems merely to spread and flow back - even when its location means its likely to be fuel fed - this is because the high speed airstream keeps the burn area away from where the pressurised fuel vapour is escaping - the explosion usually happens when the airstream slows enough for the burn point to enter the area containing pressurised vapour and creates a flash burn or explosion.

This is a reason why if you have a fuel leak on a MB at speed it is more likely to burn with a flame if it ignites - and why given the same situation you are more likely to get a much more unpleasant explosion when the bike is at standstill...

sorry for the essay

Jemma xx

don't be sorry.. I am accused of being verbose I need the company...

Ps throw out that fishtank line and get a proper line from the auto parts store it is a couple of bucks well spent. After a couple of days in the outside shed mine leaked like a sieve

its only leaking gas between his legs. let it go.

Jemma Hawtrey said:

A full tank of fuel lit from the filler neck will burn - if you are insane enough to try it........and why given the same situation you are more likely to get a much more unpleasant explosion when the bike is at standstill...

sorry for the essay

Jemma xx

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Very well said, no need for apology.