Gasoline and Fire

[Admin]

Kevin Cameron (Robert Martin/)

The only places where fire can be tolerated in association with motorcycles are in the engine’s combustion chambers, in a well-tended shop stove or heater, and, with adequate precautions, in a shop welding area. The very quality that made gasoline the ideal fuel for piston internal combustion engines makes it a constant fire danger: It quickly forms an ignitable mixture with air.

Because we handle gasoline so often while refueling cars or bikes at gas stations, it seems familiar and therefore safe to us. When a technician in a lab where I was working dropped a gallon tin of acetone (also highly volatile), forming a puddle, another tech casually flicked his lit cigarette into it. Did he believe it would go out, just as if tossed into water? The fuel-air vapor that had near-instantly formed above the acetone puddle ignited with a thump, shrouding the first man in flames. Fortunately there was an extinguisher at hand and no one was injured.

I’ve seen bikes burn at races, usually because of gasoline spilled on hot exhaust pipes during a pit stop or crash. When the dry-break connectors used for track-side refueling function properly, the dump-can separates from the bike’s fuel tank with no loss of fuel. But if its O-rings haven’t been lubed lately, a valve can hang up and drop fuel. Firemen are standing by in that situation.

Three friends were on their way to the races in a van carrying two racebikes, boring through the night. The sleepy driver did not see the succession of signs announcing “Highway Ends 3 Miles” and directing traffic to a side road. The van blew through the last sign at 70-odd mph, sailed down an embankment, and came to rest in an excavation. A 5-gallon pail of race gas (what was that doing in the van?) popped open, wetting everything and everyone in the van.

No one was much hurt and all scrambled out into the warm darkness. One of them then tottered back toward the van.

“Where’re you going?” called the others.

“I need a cigarette,” was the reply. Then his mind made the connection: cigarette, match, boom.

Such events impressed me. Others might consider me a fussbudget but I have subsequently given considerable thought to avoiding fire. When I leave my shop I unplug extension cords, upon which small rodents might munch. I store fuel away from the shop. When I can’t remember for sure that the welding tank valves are closed, I go make sure. Having spaded into compost piles and seen hot steam pour out, I know that slow oxidation, properly insulated to retain the resulting heat, can ignite fire. Hence the classic warning not to allow piles of oily rags to accumulate.

Then one day I nearly burned my shop down when a dull lathe tool ignited magnesium chips. It seemed to take me forever to realize what was happening. What is that bright white thing? As the flames just reached the ceiling, the chips were consumed and the fire died. Another rule: Don’t let combustible stuff accumulate. That’s how the Apollo 1 astronauts were killed. Sweep it up and dispose of it.

Professionals are at risk too. Once I was given a tour of an engine factory late at night. The test cell door swung open and the odor of gasoline rolled out. On its stand, the test engine above an inch of fuel on the floor continued its endurance cycle. Fuel for the dynos was stored in a 500-gallon tank on the roof. That’s why the late Charles Fayette Taylor, in his two-volume The Internal Combustion Engine in Theory and Practice, discusses dyno and testing safety. He specifically mentions the danger of gravity-feeding fuel to test engines. Fuel pumps can be switched off but, as pilots say, gravity never lets up.

Whoever had set up the test had been casual about making fuel connections, and a leak had developed. Was there a hardened-up plastic line that didn’t quite seal at its connection? Was a fuel line clip left off? Whatever the reason, fuel had leaked but its vapor had not yet reached the test engine’s hot exhaust plumbing.

We closed the dyno cell door, and my guide phoned building security.

Therefore take the need for secure fuel connections seriously. When you refuel a car, any fuel that dribbles from the nozzle just runs down the paint and evaporates. On a bike, the fuel filler isn’t in a fender. It’s above the engine, under which are the exhaust pipes or hot catalytic converter. Just something to keep in mind.

Powerboat operators know that before starting an inboard gasoline engine they must first start the ventilation fan and let it run until the engine space has been cleared of any accumulated fuel vapor. Many a beautiful boat has exploded and burned to the waterline because this rule was ignored. Taylor suggests that test cells have 24-hour forced ventilation.

Leaking fuel can accumulate in drains. I once saw a heavy iron manhole cover blown 50 feet into the air by fuel vapor igniting in the sewer below. A fuel truck had overturned and gasoline had run in all directions. The city firemen, knowing their rigs were all but useless against a gasoline fire, waited for specialized equipment to arrive from Boston’s Logan Airport.

Normally a dyno cell shares a wall with the control room. In the event of a fire, how do control room personnel escape? In one installation I visited, the only access to the control room was through the test cell. Take a deep breath, open the door, and run?

If you replace fuel lines on a motorcycle, be sure that the tubing you use is compatible with fuel. Many kinds of flexible tubing harden in contact with fuel. If subsequently disturbed, such tubing lacks the flexibility to seal, and may leak. Fuel petcocks can’t be 100-percent relied upon not to leak. Fuel leaks are a serious matter.

I’ve spoken with more than one person who lost his balance while manhandling a bike onto a service stand. The bike crashed to the shop floor. Could fuel spill during such a fall? Not if no fuel is present. Wherever sparks or flame are exposed (for example, during a spark check) be sure there is nothing for them to ignite.

While it’s sensible to have a fire extinguisher in your shop, it’s better to prevent fire than to fight it once started.

Don’t let yourself become too comfortable with fuel.

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[fastbob]

Anyone remember this ? I certainly won't forget it in a hurry .  Re Non of the day , Me for setting fire to my bike 500 miles from home . Camped at Ullapool in Scotland. Woke up , packed my gear , put on riding gear , got on bike , pressed start button, nothing . I know what's wrong because it's happened before but I thought I'd fixed it . One cylinder has slowly filled with petrol overnight and hydraulic locked the engine . So off with the gear , out with the tools , tank off , left hand plug out , move the ht lead safely out of the way ( oh yeah ) , stand well back on the right hand side of the bike to avoid being drenched in petrol and hit the starter button . Whoosh ! A fountain of petrol shoots into the air BUT the right hand cylinder has fired up and suddenly the petrol that landed back on the cylinder head is on fire ignited presumably by the loose ht lead . So what did knob of the day do ? He frantically blew on it like it was a birthday cake and , amazingly ,it went out ! Thankfully only a couple of bikers across the way saw what happened so I cheerfully waved and said " That's got it going " what an idiot ! If I had stood on the other side of the bike I would have been a human torch by now . Certainly got the heart beating in the morning !

 

 

Edited December 15, 2020 by fastbob

[onesea]

10 hours ago, fastbob said:

....... One cylinder has slowly filled with petrol overnight and hydraulic locked the engine . ........

With me I believed it was salt water. either way.....  I was not so lucky.