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"I had an incident where I was about 20 minutes from flame out, then suddenly I could hear a strange noise coming from the burner. It sounded like air being forced through a pipe. I could also smell burning rubber/plastic. When I inspected the burner, I could see a flame in the venturi tube (no flames from the nozzles). The flame was shooting straight out of the orifice fitting. Gas pressure was fine. I disassmbled the burner and found no signs of any blockage. I put it back together, fired it up and no further problems. I assumed the burning smell was either the gasket below the nozzle plate, or perhaps the rubber inside the gas hose. But after things cooled down, I couldn't tell where the smell would have come from.
Has anyone ever experienced something like this with this burner?"
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Rank: Senior Member Groups: Registered
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Hello JB
I had a similar occurance but it was because the propane bottle had gotten so low and had air in it and caused a back flush when it burped a air pocket out at the end of the bottle. At first I thought maybe I didn't have the venturi plate/fitting tight enough (ie; maybe it worked loose), but that wasn't the case. I did the same thing you did, I disassembled it, checked everything and then put it back together, got a freshly filled, new popane bottle from my local propane dealer and it hasn't happened since. But for a hot second I had about a 3 inch yellowish blue flame surgin outa the venturi plate and it scared the heck outa me.
I was using Blue Rhino propane bottles from any supermarket, but have since only used bottles filled by my local propane dealer. He told me that if one doesn't get all the air out of a bottle you might see flame outs when the tank gets low and it burps an air pocket.. How accurate that really is, I do not know, but I know I have had better luck with his refills than the supermarket tanks. Seems to last longer and I get a better burn. I did ask him how on earth does air get past the valve and I was told when left on to run dry, or, the regulator gasket gets old and allows air to get in. He told me that you can see this on the grill when it goes from a blue fame to a yellow and blue flame and shortly afterwards it just snuffs out-because the tank is finally empty. |
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Rank: Senior Member Groups: Registered
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"Hi Red, Originally Posted by: RCRed  I had about a 3 inch yellowish blue flame surgin outa the venturi plate Yep, that describes it exactly. The part that bothered me was that I reassembled the burner, attached the same gas bottle, and finished my boil without any further problems. I had to fire up my electric hot plate to keep the wort at least steeping while I worked on the burner. It took me about 30 minutes to disassemble, inspect, then reassemble, then another 5 minutes to get things back to a boil so I could do my final hop addition. I don't know if the extra steeping time is going to make my beer a bit more bitter than I want since the bittering hops were already added when this occurred ... we'll see. It's interesting that you mention ""air pocket"" as some of the posts I read on the brewing forums suggested that it could have been caused by a rogue gust of wind. I was brewing outside and there was some wind ... and the problem started suddenly. I saw a picture where the problem caused the gas line to burn. It was burned at least eight inches up the line from the venturi plate. Apparently, the poor fellow didn't recognize what was happening & the flame coming directly out of the orifice was hot enough to melt the rubber in the line, then caused some gas to escape and catch fire! When he saw flames coming off his hose it was already way too late to take corrective action & he had to just shut down. I think the bottom line is that you need to watch this burner closely ... like keeping a pair of eyes on it even when making a head call or grabbing another cup of coffee (which is the prudent thing to do anyway). If it happens again, I'll be sure to post to this thread again. One final note: It seemed like the unit needed to cool down before I could restore normal operation. It took me a few minutes to discover what was actually going on. In that time perhaps things heated up in the wrong places and that prevented me from restoring normal operation ??? ... at least until things cooled back down. Regards, --JB"
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Rank: Senior Member Groups: Registered
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Heya JB, Yes, that bit about the rogue gust (We only have periods of rogue "calm" here) is interesting. I established the lab in my metal outbuilding which is air conditioned (A must in Texas). It is not drafty at all in there so wind was not a factor. It stays pretty stable temp wise (74-78f) because of the insulation of the building (It was once a t-shirt factory of sorts prior to my purchase of the ranch). That was why I pretty much accepted the propane man's explanation. It has not happened since, but I check my bottle before I start and switch to a new bottle if I even think the existing bottle is < 50% (feels lighter than a full one based on weight). I should probably invest in a measurement dial inline so I can see how many pounds any given bottle has left. It's a pain to weigh it and try to remember the tare weight of an empty propane bottle-they vary based upon manufacture any how  Good Week ahead, Sir.. RcRed |
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 Rank: Junior Member Groups: Registered
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Ok guys, here's the lowdown. It seems to me that in most every case, you guys were throttling down the flame when this event happened. I was having this type of event happen almost every time I was running my nat gas fired turkey fryer type burner. Since I had put the burner together from parts from old water heaters, I just figured that I needed to down size the orifice a little. So I soldered up the office and redrilled it. yes, solder works. I've done it numerous times.
So here is what's happening. You are throttling down the pressure, essentially, at the orifice, to the point where you are loosing gas out of the air intake. The office needs enough pressure to get sufficient velocity to cause mixing at the air intake. Reduced pressure = reduced fuel = reduced heat = reduced mixing and lose of gas before the burner. So, are you with me here?
I don't believe for a instant that boloney about air in the tank. However, you see what happens with the low pressure at the orifice. I have a whole numbered drill set and a copy of the fuel gas code. I originally set my burner up for about 25,000 BTU, and I was getting a flame at the orifice when I was slowing things down. I resized the orifice to about 18,000 BTU and now I don't get the flame inside the orifice, but it takes about an hour to get 5 gallons of wash up to a good boil. I'm trying to figure out how to make a 2 stage burner, or two burners that I can slide in and out of the same stand.
I tried this same scenario on a propane fired turkey fryer. And yes, at very low fire, the flame would ignite inside the burner. This doesn't happen at higher burn rates b/c you have sufficient velocity and mixing.
Good luck, and Cheers
G.
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