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Question about VOC\'s

uglydoguglydog Posts: 256
edited 3:26PM in EggHead Forum
Most people suggest letting a new load of lump burn until the smoke is clear and all the VOC's have burned off. I agree with that, but if most of the lump is not burning during the first 20 or 30 minutes, how do the VOC's get burned off from that unburned lump? Are the VOC's driven off by the heat?

Next question: occasionally it is suggested that people add some lump part way through a low and slow cook, or if the fire goes out. How do you get rid of the VOC's in that situation? Let the new lump burn for 20-30 minutes before putting the food back on?

Thanks, Uglydog


  • uglydog wrote:
    Are the VOC's driven off by the heat?

    Yes. "Volatile" in this case means likely to vaporize at relatively low temps. So as the temperature rises, the volatile substances vaporize and dissipate, even if the lump isn't lit.

    uglydog wrote:
    Next question: occasionally it is suggested that people add some lump part way through a low and slow cook, or if the fire goes out. How do you get rid of the VOC's in that situation? Let the new lump burn for 20-30 minutes before putting the food back on?

    I've never had to add lump in the middle of a cook. The only time I can recall having read that is for really low temp cooks, like smoking cheese, where you need to add very small amounts of burning lump at a time (one or two pieces). In that case, the lump can be pre-lit in a chimney and added, lit, to the egg.

    I HAVE added more lump to an already hot egg, between one cook and the next. In that case, yes, let the new lump heat for a while, until the smoke clears again.
  • CBBQCBBQ Posts: 610
    In the rare occasion I have to add lump I always pull the meat.
  • I always wondered about his myself(first question that is), thanks for asking the ?

    I've never needed to add additional lump on any lo-slo I've done
    The lump (fuel) as it heats creates gasses, those off gasses is what is burning.

    Once the the heat, fuel and oxygen equalizes the fire gets more efficient and there is very little smoke.

    Once the burn is stable changing one element of the equalization will cause different outcomes.

    Reduce air will for a time will result in over heated lump and excess VOC's. Opening the dome results in some severity of flashback or a flare up. There can possibly be flashback out of the bottom vent.

    Adding fuel blocks air flow and reduces heat in the previous burn equalization. The smoke/VOC's surface and stay until the lump is heated and there is a correct air mixture estabilished.

    Reduce fuel (lump getting low) the lump looses heat, less off gasses and the burn ends.

    Restrict is as above in the beginning, eventually the heat in the lump subsides, off gasses cease and egg shuts down.

  • opening a bag of lump and laying it on the ground would get rid of a good many VOCs without ever burning it.

    an egg filled with charcoal, much of it lit, is constantly being vented. that will draw off many of the VOCs. the fact that the lump is in an environment that is hot will cause additional VOCs to be literally driven off (not even burnt). and then of course there's the stuff that gets simply burned.

    VOCs are gasses, and don't need to burn to be gotten rid of.

    adding new lump... well. you don't need to. but if you did, i think a couple things would be to your advantgae. adding to a hot fire, the VOCs would be driven off and burned off fairly quickly. in a low temp environment, well, they'd probably hang around more. they aren't trapped forever in the charcoal and then only "let out" when it burns. so some would be driven off by the draft. maybe not much would be driven out (made volatile) by the heat, i dunno.

    as for the smoke of new charcoal catching on fire, remember that "new" charcoal is going to light when it is touching 1200 degree lump, when the fire reaches the new lump. since that lump is already 1100-1200 i'd imagine the new stuff is joing the party and being fully combusted right away. it's not like lighting a lump of charcoal with 600 degree flame. the cooler it is burning, the more soot comes off simply because it isn't burning (combusting) fully. light a piece of lump with a match, you get sh!tty sooty smoke. light it with MAPP gas (or 1200 degree adjacent lump) and it burns clean right away.

    soot and smoke aren't the same as the VOCs we talk about.

    if you are wondering what VOCs really are, they are the gasses which readily combust. open a brand new bag and breathe deep. those are the VOCs. methane, propane, ethane are all types (i believe) of voltile compounds.
    This is probably more about how we are using the term and or possibly confusing the term VOC's. Possibly the wrong term in my explanation above.

    VOC's can be described as almost anything that can be smelled. Different VOC's may have different ignition points.

    The lump has to be heated enough to 'off gas', produce vapor that will burn.

    When there is no more fuel and no more 'off gassing' the fire goes out or can be put out by eliminating oxygen so there will be no ignition of those 'off gasses'.

    My above post was a weak attempt to explain what is experienced with regards to the egg.

  • KMO_QKMO_Q Posts: 150
    VOC's or Volatile Organic Compounds are carbon containing compounds that easily vaporize into the air. Not sure there are any issues with leaving meat on with new lump....
  • the lump doesn't burn by giving off a gas which then burns. the carbon in lump combines with oxygen blah blah blah. hahaha

    yes. the VOCs can be driven off and burnt, but unburnt lump sitting in your egg while the rest is burning has lost some of its VOCs by simply being exposed to a constant current of air (carried off up the chimney), and by having it's others driven off by being in a hot environment. when the lump burns, any remaining ones burn too.

    but the whiff you get when you open a fresh bag , the faintly petrochemical kinda smell, is the most free of many types of VOCs
  • Celtic WolfCeltic Wolf Posts: 9,773
    Rapid Oxidation or it rusts really fast and puts off lots of heat..
  • ... hummmm Not too long ago I had sort of a mentor that told me, in not so many words, to check things out before I post. That mentor was the great stike.

    Pretty sure I have this right - wood doesn't actually burn.

    Typical Pete, but you are on the wrong track with that crack.

    Rather than thinking you know everything, and making a lame attempt at poking fun, look it up.

  • Celtic WolfCeltic Wolf Posts: 9,773
    I am neither on the wrong track or poking fun.

    The burning cycle of wood is indeed rapid oxidation. Which is just simply rust.

    VOCc are NOT anything you can smell. The are ORGANIC compounds. You can smell wax burning, but it is NOT a VOC. Wood does not turn into gas. it combines with the O2 rapidly. That rapid oxidation releases a lot of energy. That energy is the flame and heat we cook with.

    VOCs are compounds in a suspended form NOT Gas. Want proof, take a hand full of flour and throw it in the air an apply the right amount of heat and O2 to it. See if it doesn't explode on you. That flour is not GAS. It is however a Volatile ORGANIC Compound when it's suspended in air.

    Before you condemn me how about getting your fact straight. Or could it be all those firefighting courses I took were wrong..
  • you aren't burning wood
  • TNmikeTNmike Posts: 643
    Rapid oxidation- isn't that the way a cutting torch (oxy/act-or other fuel) works? It doesn't cut the metal just rusts it real fast when heated and then the oxygen is applied? Mike
    all right, I guess I need to go search out some info. Might take a little time though cuz I am cooking.

    Just thought of something, I guess my egg is a gasser after all. The lump is just there producing gas so I can heat the food.

    Had to look that one up...

    "The flame is not intended to melt the metal, but to bring it to its ignition temperature.

    The torch's trigger blows extra oxygen at higher pressures down the torch's third tube out of the central jet into the workpiece, causing the metal to burn and blowing the resulting molten oxide through to the other side. The ideal kerf is a narrow gap with a sharp edge on either side of the workpiece; overheating the workpiece and thus melting through it causes a rounded edge."

  • Celtic WolfCeltic Wolf Posts: 9,773
    Technically yes. As Grub posted MOLTEN OXIDE OXIDE being RUST.. Just never really addressed as such.

    Iron Oxide = Iron Rust
    Copper Oxide = Copper Rust

    Etc, etc
  • the lump does not cook by putting off burning gas. lump is nearly pure carbon, and that carbon comes with other hydrocarbons trailing along having been formed by the low-oxygen process that creates charcoal.

    the volatile compunds do burn, but they are not what produces the intense heat of carbon burning. they are incidental. old lump has little or no VOCs left in it when you light up the next day reusing lump from the prior cook
  • that's correct. see, i can agree with pete.

    though the fistful of flour thing isn't correct. it's organic, but it's not a "volatile organic compound". VOCs in the sense we mean are hydrocarbons.
    hold on, I am trying to figure out at what point molten metal turns to rust in the torch cutting example.

  • Pete,

    Nor I think.



    Caledon, ON


  • you guys are all f*cked up tonight.

    can you please just google VOCs please? i'm amazed CW hasn't yet....

    yes, flour burns when you toss it in the air. but that's because it provides many ignition points. like coal DUST. lettermen used to throw burning bags of flour off the roof and they explode when they hit the ground, but not due to VOCs.
  • "VOCc are NOT anything you can smell."

    If that is the case, then paint fumes are not VOC's. OSHA or EPA wouldn't agree with that premise.

  • Celtic WolfCeltic Wolf Posts: 9,773
    I meant "everything".. Paint fumes are not ORGANIC unless that paint was made from a carbon based life form

    Neither OSHA or the EPA call paint fumes VOCs. Being flammable doesn't make them VOCs

    Have a nice evening, because I am done with this argument..
  • Kent,

    I've never seen you upset in all these years. Anybody ever tell you how attractive you are when you get angry?
    I'm sort of excited :laugh:



    Caledon, ON


  • FlaPoolmanFlaPoolman Posts: 11,675
    Thats not what the video showed little guy :laugh: :laugh:
    There is a lot of information from the Fire Department Research regarding VOC's and how fire works. Also, universities that have done research on behalf of the fire department.

    In the Army Training Manual TM 5-315 there is a section Characteristics, Chemistry and Physics of Fire that is interesting.

    In the link, page 2, left side, paragraph A. Vapors.
    "...In burning wood, heat causes the resinous substance in the wood to vaporize. The vapors combine with the oxygen of the air, and the flame from the kindling ignites the combustible vapor-oxygen gas. The he,at from the fire heats the wood, which in turn liberates more vapors and thus sustains the fire until the wood is consumed."

    Questions about the fire always come up. I had problems with my medium and from that point in time I have been interested the posts. A year or so ago I got to reading about wood burning.

    There are a lot of sources that follow the same explanation.

    Not trying to be an ass, but above you said something to the effect I am not burning lump. I chuckled when I read that but thinking on it more, if the physical wood is the burn and heat then why is there nothing solid when we see flame or flash backs. All that is the off gasses combining with oxygen until ignition can take place.

    It seems we use the term wood burning to explain the less noticeable components of a fire.

  • WessBWessB Posts: 6,937
    Just put some bbq sauce on them voc's and eat em up....prolly get hit by a bus first anyway... :)
    "Neither OSHA or the EPA call paint fumes VOCs. Being flammable doesn't make them VOCs "

    All I can say is I was fined $11,000 because OSHA did say paint fumes were VOC's and the contractor who installed the paint booth did not do it correctly.

    Been putting some sauce on some spares in between reading and typing.

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