Lampwork Etc.

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-   -   FLASHBACK (http://www.lampworketc.com/forums/showthread.php?t=96149)

Maui Greenstone 2008-06-25 3:35pm

FLASHBACK
 
So, last night I experienced this for the first time in 6 1/2 years of lampworking. My Gtt phantom flashbacked into the oxy line, got caught at the quick connect and blew a hole in the line.....It happened when i tried to turn the outer flame on. Firstly I turned on the inner and the torch "popped" which i've never ever experienced with a gtt. Then, when i turned on the outer flame It wooshed out extremely propane rich, then suddenly sucked back into the torch. I shut the torch down and looked down cause i smelled hot rubber. I touched the line and it was too hot to touch, I reached down to touch it again and the hose exploded right in front of the connection.....We are sending in the torch to get looked at by gtt and see what caused this.

Has anyone else experience this extremely frightening phenomenon. If so what was the cause?

Alison D 2008-06-25 4:54pm

Damn, Glad all your bits and pieces are still attached. Haven't had any problems with my mini cc but you are making me nervous. I am glad you weren't hurt.

Alison

Karen Hardy 2008-06-25 7:04pm

Haven't experienced it (crossing fingers).
Hope I'm wearing diapers if I ever do.

Glad you're ok!

Maui Greenstone 2008-06-25 8:27pm

Quote:

Originally Posted by Karen Hardy (Post 1929317)
Haven't experienced it (crossing fingers).
Hope I'm wearing diapers if I ever do.

Glad you're ok!

lol.....I did have to go to the bathroom right after now to think of it:lol:

PittsGlass 2008-06-25 8:52pm

Glad no one was seriously hurt. Gotta love flash back arrestors.

theglasszone 2008-06-25 8:53pm

Good Heavens!!! I'm so glad you're OK!!! This is the reason that I don't think anyone with a oxy/prop set up should be without flashbacks - on either the oxy or the prop!!!!

I hope it turns out OK and that your torch didn't suffer some sort of irreparable damage, but I'm even happier that your face/fingers/house (or studio) didn't suffer a similar fate!

Can I ask a question (since I've just set up my new Mini CC and my lines run through a hole in the garage wall and out to the tanked oxy and tanked prop. next to the garage)....if you have a similar set up, how did the hoses hold up to the heat as the flame flashed through it? I worry that where my hoses go through the wall, if I ever had a flashback experience, my wall/insulation might catch (even if not on the walls themselves - within the space between inside and outside). I have put a foil "collar" around the lines just where they run through the wall just to help prevent any sparking of the insulation, but not sure this would be much help!

Again, I'm so glad you're OK - I sure hope you can take a second to give me some feedback on my inquiry!

Take care and be safe!
DeAnne in CA

RaymondMillbrae 2008-06-28 6:57am

Hooooo-Weeeeeeeeeee!!

Flashbacks are a pretty dangerous thing. Look what "could" have happened if it would have reached your propane tank. (CLICK HERE).

A flashback is caused by the reverse flow of gases upstream into the hoses or other equipment. This reverse flow is usually the result of:

1) improper shutdown and/or startup procedures;
2) allowing cylinder pressures to become too low; or
3) a check valve that is not working properly.

You never mentioned if you had a "check valve" or a "flashback arrestor".

If you DON'T have a flashback arrestor...get one. (And double check the latter three reasons for this phenomenon).

FYI, oxygen in itself is NOT flammable. It AIDS in the combustion of flammable/combustable materials and gasses. I may be wrong - like my wifey-poo usually tells me I am - but it sounds like you had a backfire (the initial "pop" you heard) which tells me you had a small internal flame. And coupled with the oxygen in your hose, and not enough fuel pressure, may have caused your problem.

Always check your fuel pressure when initially starting, and then recheck it after you have everything set at your working pressures. And always bleed your fuel hose after you are done.

Oh yea...and try to follow P.O.O.P..

Lesson learned - the hard way.

In Christ: Raymond

Dale M. 2008-06-28 7:50am

Quote:

Originally Posted by theglasszone (Post 1929547)
.....Can I ask a question (since I've just set up my new Mini CC and my lines run through a hole in the garage wall and out to the tanked oxy and tanked prop. next to the garage)....if you have a similar set up, how did the hoses hold up to the heat as the flame flashed through it? I worry that where my hoses go through the wall, if I ever had a flashback experience, my wall/insulation might catch (even if not on the walls themselves - within the space between inside and outside)......

DeAnne in CA

This is a total no-no..... Its against National and International fire codes and probably local codes to put hoses through a wall of any type...

Only proper way it to penetrate a wall is metallic piping exactly for the reasons you state about fire danger.

Dale

theglasszone 2008-06-28 11:19am

Raymond: Gee, thanks so much for the terrifying You Tube link!!!:x I suppose as much as it was something I totally DIDN'T WANT TO SEE, it was important that I DID SEE IT!

Dale: You too!!! I totally didn't want to hear that - but again, it was important that I DID! Now what to do? What type of "pipe" do I use to run the hoses through? Where do I find it, and how much extended from inside to outside does it need to be? Please advise.

I've had half a mind to have my local fire dept. come by and give it a look over; probably best that I wrote here and of course will modify it before I even consider this.

Also, I think I heard somewhere that you should "register" with the local FD; they should and would need to know if you have a Prop tank on the residence property in case of a fire. What do you know about this?

Thanks for your advice!

DeAnne

Judi_B 2008-06-28 12:50pm

Sure glad you're OK!! Is the Phantom a surface mix or pre-mix torch? I thought that flashback didn't happen on surface mix torches.

PittsGlass 2008-06-28 1:16pm

Quote:

Originally Posted by Judi_B (Post 1933645)
Sure glad you're OK!! Is the Phantom a surface mix or pre-mix torch? I thought that flashback didn't happen on surface mix torches.

Both incidents I have been informed of were on surface mix torches (one is quoted above and the other was a Delta). It is not as common as the internal mix, but it can happen. Be safe, use flashback arrestors.

Here is an explanation, long but informative:

While this is showing internally mixed torches, the principal is the same.

http://www.youtube.com/watch?v=q4ohVQekwuo
http://www.youtube.com/watch?v=xE5Kl...eature=related

I like that they discuss gas properties and flashback. It goes along well with Raymond's link.

theglasszone 2008-06-28 1:40pm

Thanks Pam! Do YOU have any suggestions or input regarding my questions on how to properly "pipe" the hoses through the wall hole? I really wanted to work at the torch this weekend; I'm thinking I should address this first, before I even get comfy and fire it all up again! (Of course, I have sixteen million loads of laundry and three rooms with "top to bottom" cleaning requirements to complete before I can even THINK about torching... :()

~Me

PittsGlass 2008-06-28 1:48pm

Your welcome. I would check with some of the more experienced studio "contractors" here on LE. I think I know what is correct, but am not sure enough to bet your life on it.

I need to get on the cleaning band wagon as well. Laundry, dog and me ;-)

Dale M. 2008-06-28 2:22pm

A example how you to plumb in fuel gasses into a studio may be found here.

http://www.artglassanswers.com/forum...opic.php?t=208

Dale

theglasszone 2008-06-28 2:32pm

Thanks, Dale! I had to go register at that site before I could view the graphic on the link; I hope that whatever it shows, parts-is-parts can be found at Home Depot!

While I'm on the subject of SAFETY, etc., what are the requirements for OXY? Do I want to keep my OXY TANK in a different location? Right now, it's basically beside my Prop outside of my garage back wall...maybe there should be some distance between the two for safety reasons? Can't you just come over here and help me help myself? :) Thanks for everything....

~De

theglasszone 2008-06-28 2:35pm

Drats! That's two important emails I'm waiting for - registration info. so I can view this link and Sherry's Chaos tutorial!!! Patience, patience - has anybody seen my patience? Where's that confounded patience!?!

theglasszone 2008-06-28 2:47pm

(Fingers tapping...............:x)

Dale M. 2008-06-28 3:23pm

Quote:

Originally Posted by theglasszone (Post 1933829)
(Fingers tapping...............:x)

IF you are waiting for a confirmation from AGA...You are good!

Dale

theglasszone 2008-06-28 3:34pm

OK! Thanks Dale...but does this mean that I'm running my T-Grade hose THROUGH this conduit - or is it now going to require that I cut and refit it at the entry and exit points of the conduit? That would seem to add even more spots that theoretically could leak and need constant checking. If the hose line runs though the conduit, how do the "shut off" valves work - compression?

Sorry to be such a PITA!

~De

FlameFilly 2008-06-28 6:24pm

Quote:

Originally Posted by Maui Greenstone (Post 1928877)
So, last night I experienced this for the first time in 6 1/2 years of lampworking. My Gtt phantom flashbacked into the oxy line, got caught at the quick connect and blew a hole in the line.....It happened when i tried to turn the outer flame on. Firstly I turned on the inner and the torch "popped" which i've never ever experienced with a gtt. Then, when i turned on the outer flame It wooshed out extremely propane rich, then suddenly sucked back into the torch. I shut the torch down and looked down cause i smelled hot rubber. I touched the line and it was too hot to touch, I reached down to touch it again and the hose exploded right in front of the connection.....We are sending in the torch to get looked at by gtt and see what caused this.

Has anyone else experience this extremely frightening phenomenon. If so what was the cause?

I've never worked on a torch w/an inner and outer ring so I have a couple of questions.

Does your outer flame have a separate line for oxygen and propane? Are they sourced from the same place as your inner flame is?

I don't have flash back arresters and I'm on a National 8M w/the 7 holed tip which is a surface mix tip. I also use a 5lpm concentrator which gives it a weak flame but good enough to do soft glass.

What I'm trying to understand is if you have positive pressure in your lines it shouldn't combust back into the lines. My torch pops when ever I'm lighting it for the first time of a session for some reason. I usually try to bleed the propane a little before I light but it still will pop, but after the first light it doesn't do it. I still can't figure it out.

When you mentioned the pop it worried me and whether or not my set up is safe.

Dale M. 2008-06-28 6:43pm

Quote:

Originally Posted by theglasszone (Post 1933907)
OK! Thanks Dale...but does this mean that I'm running my T-Grade hose THROUGH this conduit - or is it now going to require that I cut and refit it at the entry and exit points of the conduit? That would seem to add even more spots that theoretically could leak and need constant checking. If the hose line runs though the conduit, how do the "shut off" valves work - compression?

Sorry to be such a PITA!

~De

Simply you hose connects to shut off valve at end of metallic piping inside the studio.... A short soft copper or rubber flex line connected metallic piping to tank outside the outer walls of studio...

You do not cut any of your hoses and your hoses do not go through any conduit....

This is same concept that natural gas is brought into the home....

Dale

theglasszone 2008-06-28 9:23pm

Thanks so much, Dale! After reviewing your diagram with my hubby, and going on Home Depot's on line catalog of stuff, and I've printed out everything I think we're going to need to accomplish this. I couldn't readily find shut off valves that indicate "B" fitting - the ones that I think I'm going to get are listed as "...5/8" FIP x 3/4" Flare Straight Gas Valve, quarter turn design". I hope these will fit! Everything else, now that I'm not in "WHAT THE HELL/PANIC" mode look pretty simple, too!

I think it's definitely the RIGHT thing to do!

~DeAnne in CA~

Maui Greenstone 2008-06-28 10:15pm

So after browsing this thread. My conclusion is that maybe the pressure was too low, as I had just switched over from a national 8mm. I do have flashback arrestors (thank God) and where the lines go through the wall they are in insulated metal tubes. The line got REALLY hot. Maybe hot enough to start a fire if in the right(or wrong) place. Also for anyone without flashback arrestors......GET THEM NOW....could save serious bodily harm or life.

Thanks for the feedback. This has been exactly what I hoped for.....a very information filled thread.

John

bead crazy 2008-06-28 11:15pm

WOW when I read all th info Everyone was saying that you do not need flash back arrestors for surface mix torches. So after hearing this I will be going and getting a flashback arrestor

bgurden 2008-06-29 4:32am

i have a flashback arrestor on the propane line but not on my oxygen concentrator line. it is my understanding that we dont need one for the concentrator as it is not stored fuel. i do however keep my concentrator in the laundry room next to the garage for humidity reasons. the hose is long enough to reach my torch. ive been taught that when i start my setup to turn on the oxygen concentrator and let it run for a few minutes turn on the oxygen on the torch, turn off the oxygen on the torch, turn on the propane, light and then turn on the oxygen again.

theglasszone 2008-06-29 10:37am

OK~~~I realize we've had a few "graphic" videos and such posted - but this one is well worth watching! Although it's a "classroom" safety video, you can certainly apply some of the basic concepts to your studio space:

http://www.youtube.com/watch?v=8g_arzPICEA

:fnwl:

theglasszone 2008-06-29 10:37am

Sorry - I just couldn't help myself - GOTCHA!!!

~De

PittsGlass 2008-06-29 11:22am

Quote:

Originally Posted by theglasszone (Post 1934986)
Sorry - I just couldn't help myself - GOTCHA!!!

~De

Oh snap! you got me for sure :-) Nice way to lighten up a dry thread ;-) Happy Sunday!


Back on topic... I would not "guess order" on the shutoff valves, I would check your local welding supply and be "sure" your valves are right for oxy and prop. Just that safety cop in me:hide:

Dale M. 2008-06-29 11:25am

Quote:

Originally Posted by theglasszone (Post 1934399)
Thanks so much, Dale! After reviewing your diagram with my hubby, and going on Home Depot's on line catalog of stuff, and I've printed out everything I think we're going to need to accomplish this. I couldn't readily find shut off valves that indicate "B" fitting - the ones that I think I'm going to get are listed as "...5/8" FIP x 3/4" Flare Straight Gas Valve, quarter turn design". I hope these will fit! Everything else, now that I'm not in "WHAT THE HELL/PANIC" mode look pretty simple, too!

I think it's definitely the RIGHT thing to do!

~DeAnne in CA~

Here is what actual "B" fitting looks like...



Here is how you adapt "B" fitting to outlet side of gas shut off valve...



Your best solution for locating a "B" fitting also know as a "regulator coupler" will be a place that deals with welding supplies and fittings.

Dale

PittsGlass 2008-06-29 11:33am

Dale, I have a question as you seem very prepared and knowledgeable.

Is it true that we need special shutoff valves that differ from regular compressed air systems? I have always erred on the side of caution as propane is corrosive and oxy a smaller atom.

How about quick disconnects, same question?

Thank you for your advise in advance. You may save me some $.


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