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Mechanical Killswitch

I understood what the OP meant, and I've been in a runaway truck caused by vented gaseous fuel. It ain't any f'n fun at all, and certainly isn't something anybody should be assuming couldn't happen. Diesels run just fine, either forward and backwards, when there is enough volatile compounds in the ambient air. I even saw one run backwards on what it was getting out of the oil-bath air cleaner because the D/A driving it popped the clutch too quick and it backlashed, then he panicked and held the clutch in while it ran away. An ungoverned Maxidyne doesn't sound too good.

Being able to breathe has nothing to do with this, either - natural gas, propane, acetylene, and volatile fumes are all breathable AND combustible in the right mixtures, and you don't have to be in a natural gas plant or near a blown-out well or pipeline to have that condition arise.

The only way you can shut a F/A-induced runaway off is by cutting the air supply as Leo indicated, or by stalling it out if it's a standard.

All that being said, for most people, a manual guillotine setup on the intake is probably overkill unless you ARE using the vehicle in situations where a potential F/A ambient condition is possible.
 
The OP wasnt really thinking about gaseous air, just fuel from his own system, which Dragot clarified. So no mechanical switch needed.

If you are in a concentration of air great enough to runaway an engine, then I personally would not want to be breathing it. Propane or Natural gas will suffocate you by displacing the actual air you need to breath. Not somewhere you want to be very long, especially if its an enclosed area that would explode. Good thing that the canaries died before people did or stuff blew up in the mines.
 
JiFaire said:
With a good LP, it wouldn't, I don't think. It would probably stop once the fire got going really well, though...
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yea thats probrably true. Just to be clear I was asking the question in response to daves question posted right before me.
I would not want to be around if the air is combustibile enough to lite off.
(Just thinking out loud) could an exhaust brake kill the engine also? If it choked off the ability to exit any gasses then none could enter ether right?
 
Burning oil said:
yea thats probrably true. Just to be clear I was asking the question in response to daves question posted right before me.
I would not want to be around if the air is combustibile enough to lite off.
(Just thinking out loud) could an exhaust brake kill the engine also? If it choked off the ability to exit any gasses then none could enter ether right?
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Exh. brake could work if you could manually activate it. Closing off the air is pretty much instant though which I don't think the brake would be.
 
What led me to ask the question was a post on pirate4x4; the discussion was about EMP's vs. old school vehicle electrical...

http://pirate4x4.com/forum/showthread.php?p=12670768

Camarogenius said:
FYI, The 12v cummins, and the Ford/IH 7.3 IDI both had the option of a mechanical killswitch that replaces the key activated fuel cutoff solenoid. A good downhill roll, and no electrics needed.

Come to think about it, I've heard of an air starter option as well. Don't need the hill either.
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If the 7.3 IDIs mechanical killswitch had anything to do with the IP, i'd figure it could be made to work with the 6.2 as well. Both did run the DB2 Ip afterall.
 
buddy said:
If you are in a concentration of air great enough to runaway an engine, then I personally would not want to be breathing it. Propane or Natural gas will suffocate you by displacing the actual air you need to breath. Not somewhere you want to be very long, especially if its an enclosed area that would explode. Good thing that the canaries died before people did or stuff blew up in the mines.
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Uh, no.

Check your density tables, and understand that gasses are miscible. A heavy gas, in a low spot, will eventually displace enough air to create a no-oxygen situation, but by then it isn't explosive, either, because the flame front will only happen on the interface.


We had a guy walking through a compressor station a number of years ago, minding his own business, when the whole place exploded around him because the concentration finally reached flash concentration and a suppressed burner set it off.

Blew up the whole building - roof, walls, doors, all gone. Left just the frame. He got a nasty knot on his head trying to run away after the explosion - no damage from being in the middle of it. Compressors were still running fine, just suddenly open to the elements.
 
Uh well sorry for not being so accurate in my statement, but Im assuming you dont want to breathe air with less than 19% oxygen, let alone no-oxygen when the gas mixes/displaces the oxygen, whatever you want to call it.
 
Anyone need one of these cable operated emergengy shutoff valve's???
i got one for sale,complete with short intake top.
Its boxed up,ready to go.

I had it sold to a site member,but he left me hanging.
 
buddy said:
Uh well sorry for not being so accurate in my statement, but Im assuming you dont want to breathe air with less than 19% oxygen, let alone no-oxygen when the gas mixes/displaces the oxygen, whatever you want to call it.
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Buddy, all I'm saying is that you can breathe just fine in an explosive atmosphere. It isn't recommended, but it can be done.

If the volatile gas (ie methane or propane, or a mixture in a more colloidal state with volatile fumes like gasoline or kerosene) displaces all the oxygen, it won't burn. Of course, you are dead already, so a little fire isn't an issue.
 
One more situation a mechanical air shutoff device becomes handy; turbo seal or severe piston wear/damage, engine will continue to run on crankcase oil even with ignition key in off position, air shutoff is standard equipment in VW TDIs (anti shudder valve), and many Diesel engines for that matter have solenoid or cable operated air shutoffs, probability of it happening is low but if runaway happens C02 squirted in intake or rag over intake are only ways to stop the runaway if you aren't equipped with a shutdown air flapper.
 
Burning oil said:
yea thats probrably true. Just to be clear I was asking the question in response to daves question posted right before me.
I would not want to be around if the air is combustibile enough to lite off.
Click to expand...

It is a little exciting when the alarms go off. Household natural gas is 'sweet'; it does not contain the stinky hydrogen sulfide that can kill you, so we add an odorant agent called mercaptan to let you know it's there when you have a leak. In low concentrations, you can't smell natural gas mixed in the ambient air, and it won't explode, either, but if it gets into your engine, it will definitely detonate and act as a fuel source.


Burning oil said:
(Just thinking out loud) could an exhaust brake kill the engine also? If it choked off the ability to exit any gasses then none could enter ether right?
Click to expand...

Sorry Leroy, missed this in all the excitement... yes, an exhaust brake can kill an engine, but it is pretty tough to do that and in a runaway situation, it probably won't be able to hold it back. Intake is better because the volumes are so much smaller and you aren't being driven by the engine. Think about stopping an engine with your hand... once by putting it over the intake, next by holding it over the exhaust. Which works best?
 
I put propane right into my engine, so I know you can get a pretty good concentration before a runaway, and thats combined with diesel fuel. I fumigate it even at little to no boost when cruising. NG has a little more BTU, but also lets not think NG in our homes can't kill you. It will mix with the air and suffocate you, just not kill you from being toxic and limited exposure.

I experemented with my valve wide open before, and only time I actually got a little rise in speed without the pedal is when I had sustained high boost that esssentially sucked more propane out of the tank. In gear under load it barely did anything. At idle in park that concentration would have surely run the RPMs up, but it took the turbo sucking the propane out to do that. Unless you are in an eclosed garage with a gas leak I dont see this being likely. I also have lots of blowby, very oily intake. I had oil coming out around seams on bad turbo coupler seals. my old EGR intake was covered with oil gunk. It would take a serious, serious turbo seal leak to the compressor housing to get enough oil in there to cause a runaway. And look at Bill Heath who puke huge amounts of oil into his intake, it just made it run worse.
 
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http://www.wellservicingmagazine.com/diesel-engine-risks-while-operating-hazardous-environments
http://www.amot.com/Z_Dead%20Datasheets/4261.asp
http://www.mckenziecorp.com/air_intake_valve.htm
http://www.pump-zone.com/valves/valves/controlling-runaway-diesel-engines.html
http://www.myturbodiesel.com/1000q/stop-runaway-diesel-engine-how-to.htm

(I threw in the last one for Tim)

I know, you don't believe all of us who live and work with the stuff, but facts are facts... if you want to drive your diesel truck within 30 m of a wellsite up here, you need an intake cut-off installed.

FWIW, You also need to have your "H2S Alive" certification before we let you OUT of your truck, because it means you know about things like breathable atmospheres containing methane or other volatiles, because on-site, what you don't know is likely to kill somebody else.

Methane in air in concentrations that will not ignite WILL make your truck engine over-run. And no, methane will not suffocate you at low explosive concentrations. Where did you get that idea? If your house fills up with the stuff (enclosed space with infiltration greater than exchange, sure, but there's a long way to go before then, and all of it explosive. Once (if) the air is all displaced, the stuff won't even burn, much less explode.
 
I never said anything contradictory to what youre saying. I didn't say you dont need one to be in those areas. All I said was this is most likely to be an issue in an enclosed area that is hazardous to your health. Exactly as you say.

I work in confined spaces underground, have required training and know the effects of low oxygen environments and LEL. I have installed LEL sensors.

AND, if you pay attention the OP was worried about his own fueling system causing a runaway, thats why I try to explain the low likelihood of being in this situation.
 
buddy said:
I never said anything contradictory to what youre saying. I didn't say you dont need one to be in those areas. All I said was this is most likely to be an issue in an enclosed area that is hazardous to your health. Exactly as you say.

I work in confined spaces underground, have required training and know the effects of low oxygen environments and LEL. I have installed LEL sensors.

AND, if you pay attention the OP was worried about his own fueling system causing a runaway, thats why I try to explain the low likelihood of being in this situation.
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Honestly what I was more interested in, was trying to go Completely mechanical.. I.E. NO batteries or Alternator required..
 
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