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  #1  
Old 2005-12-06, 5:09pm
A.Loomis's Avatar
A.Loomis A.Loomis is offline
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Question How much OXY, how much PROPANE......

Hi all,

I am a new lampworker, and want to understand the flame better. Do you have links/resources?

Here are some of my questions that have come up as I work....

a normal working flame--do the "cones" at the mouth of the torch (Nortel minor) have well defined edges, or should I be working with slightly "fuzzy" edges for a good mix? This one bugs me every time I turn the torch on - I don't know if I have it "right" and worry about working too close to myself all the time...I try to stay out at the right sweet spot.

What happens when you turn up the OXY? The flame gets smaller/hotter, right? So, what do you use that for? How can I make the most of the concentrated flame? What should I be careful of -- like crazy color stuff that happens....or when you want the crazy color stuff like the reduction frit.

I would love to just read and read about this, and then go out and try it...

THANKS in advance for your links/advice/good ideas !!

Angela
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  #2  
Old 2005-12-06, 6:18pm
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Typically you run oxygen pressure double what your fuel pressure is, so if oxy is at 10psi, your fuel should be at about 5psi for working soft glass... For Boro you probably need to run oxygen at 3x fuel pressure so oxygen should be about 15psi and fuel at 5 psi... Of course you may find different pressures that work better for you dependging on what you are doing...But these pressures/ratios are pretty good starting points.

Cones should be well defined and about 1/4 to 3/8 long and have end 1/4 of tip of cone yellow while rest of cone is blue... This is pretty much a neutral flame setting....

Running oxy up tends to cause a oxidizing flame and the extra oxygen in flame tends to make it a cooler flame...

Dale
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  #3  
Old 2005-12-06, 8:38pm
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Whimsey Whimsey is offline
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On an oxy con, what should the reading be when mixed with the propane? I am alsdo on a minor and have often wondered this. I never really know if I have the oxygen knob on the torch turned to high or not high enough.

so buy adding more oxygen to the flame, you get a cooler flame? Which is good for what? What would the hotter (less oxy) flame be for then?
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  #4  
Old 2005-12-07, 6:40am
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And, because I'm new, and not 100% on understanding the flame, I'm getting some scum/black in my encasing. This happens sometimes, not all the time, and I keep telling myself to work FARTHER out in the flame to avoid the blackness.

What causes the black stuff in the clear? Too much propane? Working too close to the cones of the flame?

I also sometimes get reactions in some of the glass colors I'm working (esp. the greens, but also sky blue yesterday) Should I work farther out? Should I have the oxy turned up more?

BTW, I am on an oxy con.... minor burner, propane tank outside, etc etc

THANKS,
Angela
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  #5  
Old 2005-12-07, 6:51am
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Ok - with an oxygen concentrator, keep in mind that they "mostly" operate at about 8 PSI, with an oxygen concentration of about 94%. This equates to a delivery pressure of about 6 PSI "pure oxygen". Propane pressure for soft glass should be about half of that or 3 PSI.

Many regulators currently being used have a very high total delivery pressure - 60, 90, even 120 PSI top scale range. These regulators cannot accurately delivery low pressure - under 10 PSI - because it's almost impossible to set the regulator that low, and most regulators are only accurate in the middle 60% of their range.

My guess is that you still have your propane pressure too high. Black scum is an indication of a reduction flame.

Your inner cones should only be as long as the diameter of the glass rod you are using. The very tip, not 1/4 of the cone, but only the very tip of the cone should be whitish yellow.

The total length of the flame should be about as long as the span between your little finger and thumb, usually about 6 inches or so.

Do work further out in the flame, try not to be right up against the cones. The actual hottest part of the flame is about 1" beyond the tips of the cones, and I'd work further out than that.
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  #6  
Old 2005-12-08, 7:02am
VickiK VickiK is offline
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Angela, I started lampworking this past Feb. and I've had the same problem with working too close to the torch. I have to constantly tell myself to move out in the flame. Fortunately, I have gotten better with time. But I still tend to work really hot.

I could use some help as well. Right now, my problem is oxygen. It seems like I use A LOT of oxygen! I'm on a minor also. Being new, I guess it could be the fact that it takes me longer than a more experienced lampworker, am I right? I've tried to read all the threads I can on this subject and somewhere (maybe here at LE, maybe somewhere else) I seem to recall someone advising that the oxy be much higher. This could also be the problem. Does anyone know how many working hours you should get out of a tank?
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  #7  
Old 2005-12-08, 8:39am
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Quote:
Originally Posted by VickiK
. Does anyone know how many working hours you should get out of a tank?

First question is what size tank?....

The higher the oxygen pressure and the more you turn up then flame, the higher the consumption rate.... Conservation is the key, only use a enough flame to accomplish task at hand...

Dale
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  #8  
Old 2005-12-08, 8:50am
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Respectfully, Dale, I disagree. Conservation leads to bad mixture settings and poor glassworking results. A smaller cooler flame does not result in good beads.

This seems to be one of those never ending discussion points - but the thing is, it's basic chemistry. At a minimum, you need 2 PSI of oxygen for every PSI of propane you burn. You cannot get around this rule, if you try, you will end up with a reduction flame and bad glass.

Oxygen usage is part and parcel of what we do. You cannot compromise on your usage.

When I was working on smaller torches, I'd typically blow through a "K" oxygen tank in one week and a 20 pound BBQ tank of propane in 4 weeks. Other people have reported similar results. Now that I'm running a larger torch (Tiger Shark), I'm using the equivalent of a "K" oxygen tank in about 3 days, and a 20 pound BBQ tank of propane in 3 weeks.

Keep in mind that if you get an oxygen concentrator, your purity of oxygen is actually less than tanked oxygen, and you will have to work with lower propane pressures to compensate. Going to a concentrator may not always be in your best interests because of that.

Essentially, you do have to "deal" with it (no insult intended). Do what works for you. There's no way around it, oxygen is expensive, but it's just like a kiln, you have to have it.
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