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Sudden ignition of VOC's?

mlamb01mlamb01 Posts: 210
edited January 2016 in EggHead Forum
I've had my egg for about a year and a half, and only within the last month I've had 2 instances of where my egg exploded while waiting for it to come up to temp.  Here's what I mean...  I light the lump(royal oak), starter goes out, I close the dome and leave both vents open.  Then I wait for the temp to get about 50 degrees higher than where I want it, and then I will put the daisy wheel on.

So I close the dome, white smoke is coming out of the top, and I am hanging out around the egg waiting for the temp to come up.  I'm standing about two feet from the egg, looking at the temp, and I hear a thump and see what looks like an 18" flame come out of the top and bottom vents at the same time!  It was followed by the sound of rushing air.  The fire that came out of the top was cone shaped, and reminded me of how a blowtorch looked.  The fire coming out of the bottom had a similar look.  Luckily it was cold and I had pants on, but I still felt the heat from it on my legs.  Whole thing lasted maybe 1/2 second tops, but scared the crap out of me.  Makes the backdraft you get from forgetting to burp the egg seem insignificant.  This was not caused by opening the lid, or closing the vents off.  Daisy wheel was off, the bottom vent was wide open, and lid/dome was closed.

After this happens, the smoke coming out of the top vent is suddenly clear.  It instantly clears up.  I'm suspect that some volatile gasses are building up in the egg, even with the top off, and when the temp reaches around 300 or so, those gases suddenly and violently ignite.

I use royal oak 99% of the time, and never experienced this until just recently, within the last month, when it has happened twice.  The first time I heard it and felt some heat from it, but I had my back turned to the egg and I was maybe 6 ft from it.  By the time I turned around to look I did not see anything, but I did notice my smoke had suddenly cleared up.

This happen to anyone else?  I'm wondering if I may have a defective bag of lump.  Flames coming out of the top doesn't bother me too much, but when they come out the bottom vent like that I get worried.  If you are standing close enough to open the lid, your legs would be hairless and possibly burned.

Comments

  • It's funny you brought this up...I actually had the same thing happen to me over my last cook (in which I didn't use my Stoker).  I was using the BGE Lump at the time.  Will need to follow this thread to see what others have to say.
    North Pittsburgh, PA
    1 LGE
  • LegumeLegume Posts: 11,456
    Yikes.  My first reaction was "cool!" but it actually sounds scary.  No idea here, glad you're not burned.  Makes me think back to the cooking in the garage thread from yesterday.
    I do not have any broken or spare parts for any size egg.
  • stlcharcoalstlcharcoal Posts: 4,376
    After this happens, what is the dome temp?  Does the charcoal have flames or is it red hot yet?  When you put the daisy wheel on, do you also close the draft door?

    It sounds more like an oxygen issue than "gases".  You have a oxygen hungry fire going then you put the cap on it restricting the exhaust.  Temp continues to rise, exhaust gases are snuffing the fire, then they clear out the top after a few seconds and the O2 hits the heat......BOOM!  The only place it has to go is out the bottom vent since the top is restricted.

    It could be some combo of the dreaded VOC's, but while they do have "volatile" in the name, they are not explosive nor that "volatile".  They off gas and burn a little, but they don't produce this kind of reaction.  This just sounds like you got a fuel/air mixture in a funk and that's the reaction.

    Always limit your intake before your exhaust, and problem solved.
  • Sea2SkiSea2Ski Posts: 4,070
    I was thinking exactly what @stlcharcoal  stated. When you have that much unreleased energy, and not enough oxygen, this will happen. It has happened to me several times. A few days, the egg puffed as you described like a steam locomotive for 3-5 puffs.  Once I started restricting the intake before the exhaust, I was good.  Just remember to burp the egg if you are going to open the lid for some reason, the backdraft can be very large in this scenario.  
    --------------------------------------------------
    Burning lump in Downingtown, PA or diesel in Cape May, NJ.
    ....just look for the smoke!
    Large and MiniMax
    --------------------------------------------------

    Caliking said:   Meat in bung is my favorite. 
  • fishlessmanfishlessman Posts: 27,359
    when ive had the fire shoot out the lower vent it was with lump with alot of lump dust mixed in. the whole egg starts rumbling, then the fire shoots out. its different than a flashback
    fukahwee maine

    you can lead a fish to water but you can not make him drink it
  • mlamb01mlamb01 Posts: 210
    edited January 2016
    When this occurred I was still in the warmup stage, the daisy wheel was off, and the bottom vent was wide open.  Only restriction is that the dome is closed.  I don't know what the coals looked like inside, the dome was closed and no way am I going to lean over and look down the hole in the dome after this just happened.

    Temp was not unusually high after this flash/explosion, probably around 300 or so.  This happens very quickly and afterwards you are like, "what just happened?"

    I get the puffing out of the bottom vent on a regular basis, usually with a little flame too.  This happens after I reach my temp, and I put the daisy wheel on.  I'm expecting it to happen.  I know its going to happen so I stand clear.

    Here's a time table...

    1) I light the egg by placing a weber starter cube thru the bottom vent.
    2) About 7 to 10 minutes later, after the cube is almost gone, I close the dome.
    3) About 5 minutes later, the explosion happens.  Dome temp around 300.
    4) Another 5 minutes later, dome temp is around 400, and I put the daisy wheel on.
    5) Another 5 minutes later, the temp dropped back to 350 and stabilized, and I start cooking.
  • listen to stlcharcoal, and what fishless says is a twist on it too.

    sometimes it is because you have starved the fire after igniting a big bed of coals.  before the fire dies down, it's almost like it is lying in wait.  pissed off at you for shutting down its supply of oxygen.

    when you open the dome, you inject a pantload of oxygen, and the fire jumps out to greet it and remind you to pay attention


    as fishless says too, a variation of this is when you have a lot of dust, like grain in a silo.  the fire is limited by the lack of oxygen when the vents are narrowed, and so it sort of just chugs along.  this is how an egg maintains temp during a regular cook.  if the fire isn't a large bed of angry coals that you have just choked down, but is instead just a regular stable fire, opening the dome is usually no big deal.

    but if you have a bottom of the bag, lots of dust, those bits of dust can also ignite in an explosive sort of way, when the lid is opened.  the oxyegn doesn't ignite because of a large bed of coals, but instead because you have all this microscopic dust mixed into the air.  like a silo explosion.

    looks just like a flashback

    when you choked a fire, the fire will continue to lok for air for a while, until the coals die down/  sometimes the flame will shoot out the bottom vent
    [social media disclaimer: irony and sarcasm may be used in some or all of user's posts; emoticon usage is intended to indicate moderately jocular social interaction; the comments toward users, their usernames, and the real people (living or dead) that they refer to are not intended to be adversarial in nature; those replying to this user are entering into a tacit agreement that they are real-life or social-media acquaintances and/or have agreed to or tacitly agreed to perpetrate occasional good-natured ribbing between and among themselves and others]

  • SmokeyPittSmokeyPitt Posts: 10,472
    edited January 2016
    mlamb01 said:
    When this occurred I was still in the warmup stage, the daisy wheel was off, and the bottom vent was wide open.  Only restriction is that the dome is closed.  I don't know what the coals looked like inside, the dome was closed and no way am I going to lean over and look down the hole in the dome after this just happened.

    Temp was not unusually high after this flash/explosion, probably around 300 or so.  This happens very quickly and afterwards you are like, "what just happened?"

    I get the puffing out of the bottom vent on a regular basis, usually with a little flame too.  This happens after I reach my temp, and I put the daisy wheel on.  I'm expecting it to happen.  I know its going to happen so I stand clear.

    Here's a time table...

    1) I light the egg by placing a weber starter cube thru the bottom vent.
    2) About 7 to 10 minutes later, after the cube is almost gone, I close the dome.
    3) About 5 minutes later, the explosion happens.  Dome temp around 300.
    4) Another 5 minutes later, dome temp is around 400, and I put the daisy wheel on.
    5) Another 5 minutes later, the temp dropped back to 350 and stabilized, and I start cooking.
    I wonder if lighting from the bottom might be setting you up for this condition.  If you are putting the starter cube under the fire box then all the lump on top of your fire might be preventing blocking the way for the fire to exhaust out the top.  Perhaps the sudden flame up was when the exhaust finally "pushed through" the lump and there was a sudden inrush of oxygen. 

    Maybe try lighting from the top?  I like to dig out a little hole in the lump and then lay some pieces over the starter cube.  


    Which came first the chicken or the egg?  I egged the chicken and then I ate his leg. 

  • ChubbsChubbs Posts: 6,928
    edited January 2016
    Didn't read all of the lengthy responses above so forgive me if already covered.

    First, start closing vents down before your desired temp and then fine  (edit) tune. 

    Second, you really don't need the daisy wheel unless you are going low and slow. 

    Third, you are choking the fire when you get it hot then try to bring down quickly. Thus the boom and flame. 

    Finally, try a different lump. I realize RO is economical, but you can find much better lump for around same cost. 
    Columbia, SC --- LBGE 2011 -- MINI BGE 2013
  • Carolina QCarolina Q Posts: 14,760
    Why are you bringing the temp up 50° BEYOND target? I've never heard of anyone intentionally doing that. Bring it up to 50° BELOW target and then start closing down the vents so that you don't go over. 

    I rarely use the daisy. I control the heat with the bottom vent only. Top is wide open. If a lo n slo cook, I add the daisy, otherwise, no.

    I hate it when I go to the kitchen for food and all I find are ingredients!                                                                                                                                                                                                                           

    Michael 
    Central Connecticut 

  • @carolinaQ for a while there seemed to be a new-user mantra (perpetuated by dealers?) of "getting a good fire going" and then lowering to temp. 

    a good way to make an unstable fire, and waste fuel actually.
    heck.  i just light the thing and set vents now. 
    [social media disclaimer: irony and sarcasm may be used in some or all of user's posts; emoticon usage is intended to indicate moderately jocular social interaction; the comments toward users, their usernames, and the real people (living or dead) that they refer to are not intended to be adversarial in nature; those replying to this user are entering into a tacit agreement that they are real-life or social-media acquaintances and/or have agreed to or tacitly agreed to perpetrate occasional good-natured ribbing between and among themselves and others]

  • mlamb01mlamb01 Posts: 210
    @Carolina Q - I generally cook somewhere between 300 and 400 degrees dome temp, and I have found that if I want to cook at 350, I can put the daisy wheel cap on when the temp hits 400, and the temp will drop back to 350 and be stable within 3 to 5 minutes.  I know I do choke the fire back when I do this, and I do get some puffing and maybe some flame out the bottom when I put the daisy on, but I in my experience I get stable at my target temp more quickly this way than if I start closing the vents 50 degrees before my target temp.  Also seems to clear the smoke quicker this way as well.

    I only do this when I cook at hotter temps...  If I am doing a low and slow at 250, I start restricting the air at 200 and slowly approach 250. 
  • Carolina QCarolina Q Posts: 14,760
    @carolinaQ for a while there seemed to be a new-user mantra (perpetuated by dealers?) of "getting a good fire going" and then lowering to temp. 

    a good way to make an unstable fire, and waste fuel actually.
    heck.  i just light the thing and set vents now. 
    Never heard that, but then, I haven't been to a dealer since I bought my egg about 6 years ago. =)

    I seem to have gravitated to 400° raised direct for almost all cooks. Makes it even easier to "just light the thing and set vents now". Not likely to come outside and find a 900° fire either!

    I hate it when I go to the kitchen for food and all I find are ingredients!                                                                                                                                                                                                                           

    Michael 
    Central Connecticut 

  • stlcharcoalstlcharcoal Posts: 4,376
    @carolinaQ for a while there seemed to be a new-user mantra (perpetuated by dealers?) of "getting a good fire going" and then lowering to temp. 

    a good way to make an unstable fire, and waste fuel actually.
    heck.  i just light the thing and set vents now. 

    Man why didn't I think of that????  Haha.

    @mlamb01 .......Shoot for 50F under is a better tactic if you want a constant temp.  But if you're going to grill, it's not bad to get the heat up and then snuff it a bit--reason is, it helps get the fire spread across the entire firebox.
  • tfhansontfhanson Posts: 219
    Reading a lot of interesting and different things in this thread.  To address the OP statement.  Sounds like to me, could be the lighting it from below issue.  Could just be a matter of the "fire" settling.  This problem could just be a collapsing of your fire. especially if you are stacking New lump on top of used lump. 

    Second, am I reading this right?  You are lighting your fire with a closed dome?  That's interesting to me.  I use a looflighter, so I am lighting from top, but I leave the dome open for 10 minutes to get the fire going.
    Johns Creek, GA - LBGE and a some stuff
  • mlamb01mlamb01 Posts: 210
    @tfhanson - No, I light with the dome open.  Once the starter cube burns out, I close the dome, leaving all vents fully open.  Step #2 in my timeline.

    @stlcharcoal - I had the same thought about using the higher temp to spread the fire, and get a bigger effective cooking area.  I find it very easy to choke the temp back down to 350 to 400 if the egg was only at 450 for a minute.
  • Ragtop99Ragtop99 Posts: 1,570
    mlamb01 said:
    @Carolina Q - I generally cook somewhere between 300 and 400 degrees dome temp, and I have found that if I want to cook at 350, I can put the daisy wheel cap on when the temp hits 400, and the temp will drop back to 350 and be stable within 3 to 5 minutes.  I know I do choke the fire back when I do this, and I do get some puffing and maybe some flame out the bottom when I put the daisy on, but I in my experience I get stable at my target temp more quickly this way than if I start closing the vents 50 degrees before my target temp.  Also seems to clear the smoke quicker this way as well.

    I only do this when I cook at hotter temps...  If I am doing a low and slow at 250, I start restricting the air at 200 and slowly approach 250. 
    I've done it this way too when doing things at medium heat like a chicken.  If temp overshoots and it is caught before it too long, the air temp might be 400, but ceramics can be much cooler and reducing the fire will cause the temps to fall back to 350 or less within a couple minutes.  Adding the food also causes the temp to drop even more. 

    From a flashback standpoint this a bit riskier because the fire was bigger and there are more coals that were very hot than if I had caught the temps on the way up.  Opening the lid will allow air to reach more still hot coals which can trigger the flash.   I open and close the lid slowly, and when I put the DW on, I put it on slowly to reduce air flow disruptions.

    Cooking on an XL and Medium in Bethesda, MD.
  • I have had this happen as well. My theory is this. You light the top with your choice of methods and the fire begins to burn. you have an air flow problem through the charcoal forcing the oxygen to travel from the bottom vent around the outside of the firebox to the top side of the charcoal. The fire always works its way down to the bottom of the fire box and when it does, there is a sudden free flow of air straight up the middle of the pile of burning charcoal causing it to flare up. It does this with more pressure than is able to escape through the top vent and ends up exiting through the next best route at the same time which is the bottom vent. This could disturb the pile of coal somewhat causing it to collapse on itself setting up the flare out condition to occur again until the coal is actually loose enough to burn normally. IMHOFWIW

    1 large BGE, 2 small BGE, 3 Plate setters, 1 large cast iron grid, 1 pizza stone, 1 Stoker II Wifi, 1 BBQ Guru Digi-Q II, 1 Amaze N pellet smoker and 1 empty wallet.      Seaforth, On. Ca.

  • WhoozherWhoozher Posts: 2
    edited May 2018
    WARNING:
    I will NOT open my dome without a elbow fire cooking mitt again. I know sometimes I have to “burp” the egg to let the fire settle down but the other night I did that and then opened all the way and a huge fireball followed my hand all the way up! Lucky it only singed the hair on my arm but it was dangerously close to be a serious burn incident.
    Another word of CAUTION...do NOT wear plastic food service gloves while putting chicken etc. on cooking surface. If you have them on and the above described fireball happens it will melt to your skin.
    im probably a dunder head but if this word of CAUTION prevents anyone from serious injury ...... sharing this will be worth it.

    PS..... I LOVE MY BGE!!

  • JohnInCarolinaJohnInCarolina Posts: 19,944
    Whoozher said:
    WARNING:
    I will NOT open my dome without a elbow fire cooking mitt again. I know sometimes I have to “burp” the egg to let the fire settle down but the other night I did that and then opened all the way and a huge fireball followed my hand all the way up! Lucky it only singed the hair on my arm but it was dangerously close to be a serious burn incident.
    Another word of CAUTION...do NOT wear plastic food service gloves while putting chicken etc. on cooking surface. If you have them on and the above described fireball happens it will melt to your skin.
    im probably a dunder head but if this word of CAUTION prevents anyone from serious injury ...... sharing this will be worth it.

    PS..... I LOVE MY BGE!!

    Welcome to the forum!  
    "A generation of the unteachable is hanging upon us like a necklace of corpses." - George Orwell 

    "I've made a note never to piss you two off." - Stike

    The other ahole

    Living large in the 919
  • JohnEggGioJohnEggGio Posts: 1,424
    edited May 2018
    I would guess this comes from lighting from below  - burst occurs once fire has burned through the blanket of charcoal above - which had been choking the flame.
    Maryland, 1 LBGE
  • XC242XC242 Posts: 1,208
    You say you close your dome as soon as 7 minutes after lighting the starter cube. I’ve never closed up sooner than 15 - 20 minutes after lightning (using any method). I think you just need to wait longer before closing the lid. Doing it this way I’ve never had a problem even maintaining low and slow temps. Give it a try next time and see how it works for you. 
    LBGE (still waitin' for my free T-Shirt), DIgiQ DX2 (In Blue, cause it's the fastest), Heavy Duty Kick Ash Basket, Mc Farland, WI. :glasses:  B)
    If it wasn't for my BGE I'd have no use for my backyard...
  • goldrushgoldrush Posts: 1
    You have to wait for the smoke to turn clear then you put the daisy wheel on and adjust your vents.
  • SkySawSkySaw Posts: 656
    Were you at the bottom of your bag of lump? The small pieces and dust restrict airflow in the BGE, which causes the problem you describe. 
  • jeffwitjeffwit Posts: 1,348
    Whoozher said:
    WARNING:
    I will NOT open my dome without a elbow fire cooking mitt again. I know sometimes I have to “burp” the egg to let the fire settle down but the other night I did that and then opened all the way and a huge fireball followed my hand all the way up! Lucky it only singed the hair on my arm but it was dangerously close to be a serious burn incident.
    Another word of CAUTION...do NOT wear plastic food service gloves while putting chicken etc. on cooking surface. If you have them on and the above described fireball happens it will melt to your skin.
    im probably a dunder head but if this word of CAUTION prevents anyone from serious injury ...... sharing this will be worth it.

    PS..... I LOVE MY BGE!!

    Welcome to the forum!  
    @JohnInCarolina, your use of sarcasm is pure gold. I bow to your mastery of the art.  ;)
    Jefferson, GA
    XL BGE, MM, Things to flip meat over and stuff
    Wife, 3 kids, 5 dogs, 4 cats, 12 chickens, 2 goats, 2 pigs. 
    “Honey, we bought a farm.”
  • JohnInCarolinaJohnInCarolina Posts: 19,944
    @jeffwit - thanks!  Not everyone around here appreciates my caustic wit.
    "A generation of the unteachable is hanging upon us like a necklace of corpses." - George Orwell 

    "I've made a note never to piss you two off." - Stike

    The other ahole

    Living large in the 919
  • WhoozherWhoozher Posts: 2
    @jeffwit - thanks!  Not everyone around here appreciates my caustic wit.
    You got to have “caustic wit” before anyone would appreciate it. You dig?
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