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  #1  
Old 2006-08-16, 1:30pm
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Default Proper pressures for a Piranha

So I finally got to (briefly) light up my Piranha. I say briefly, because hubby isn't finished with ventilation yet (why is that ALWAYS the last thing to get done - sheesh!) and I didn't want to gas myself to death.

Anyway, I noticed that it was a tad "hissy" at what I thought should be proper O2 and propane pressure, going by the doco. I searched through the Torch section and didn't really see anything that says - "these pressures work really well".

I'm running on O2 TANK and propane. I started at 10 (o2) and 5 - I figured "more is better... right?" and that's at the "top end" of the range. When I couldn't get it to stop hissing, I turned it down to 8 and 4, but could only stop the hissing with a slightly reducing flame, not a neutral flame. At that point, I knew I was inhaling more gases than was healthy, so I quit.

How low should I turn it down? Am I doing something else wrong, that it should really work right at those pressures?

Thanks
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  #2  
Old 2006-08-16, 2:41pm
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What do your candles look like? Are they even or uneven? Is the center candle much, much longer than the rest? Are you adding more oxygen to "clean it up" (get the yellow tips off any/some of the candles)?

PS I forgot to mention this, but it really should work right at those pressures. I'm not so sure that it is something you're doing "wrong," though.

Last edited by kbinkster; 2006-08-18 at 10:56am.
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Old 2006-08-19, 12:10am
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Does your flame look anything like the flame from the Betta in this thread?
http://www.lampworketc.com/forums/sh...ad.php?t=31081
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Old 2006-08-19, 12:38am
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Hey, when you say "hissiing" what does it sound like? My pirahna makes a sort of a humming hiss. I took it to Frantz and hooked it up to their gas to see if it was my quick connects or something and all of their torches made the same noise. Neither my Minor or my DH's Cheetah make the noise here.

Needless to say I was confused by this.
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Old 2006-08-19, 9:36am
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Kevan, I was just thinking about your humming Piranha - no kidding! Have you (Kevan) tried changing the pressures to see if the pitch of the hum changes?

It is possible that there is a burr (from machining) somewhere in the torch that is creating that hum. It could also be in a valve.

I don't think that it presents any danger.

So, when you say all the torches at Frantz, which ones did you see/hear? Because, that is odd.
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Old 2006-08-21, 8:29am
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OK. I finally got to work on the torch for a longer stretch this weekend (longer = more than 10 minutes before gassing myself senseless!) as the ventilation is now done!

The 5 candles on the outside are a nice blue. The center candle is taller and more yellow - not nearly as yellow, bushy, or tall as the one you pointed out kbinkster. It's closest to flamedancer's candles in this picture, but more yellow on the center candle.
http://www.lampworketc.com/forums/sh...+center+candle

I started out running my propane at 4, and my oxygen at 8, but it was "hissing" a lot - fairly noisy, so I backed the oxygen pressure down to 6 and got less hiss and noise. I don't really know how to describe the hissing, other than - hissing. If I crank up the oxygen (at the torch) the noise gets louder, and if I dial it down, the noise gets less. So I'm sure it's something to do with the oxygen pressure.

Which is complicated by the fact that the oxygen regulator that my husband picked out for me is a nice one, but it doesn't "do" low pressures on the gauge really well. The first line on the gauge is 5psi, and the first number that's listed on the gauge is 30, so it's kinda tough to really tell what it's set at. He thinks we can just change the gauge, I think we need a different regulator.
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  #7  
Old 2006-08-21, 11:16am
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The thing is, you should be able to run the oxygen pressure at 20 psi and not have any problems.

What I suspect is going on is that you are dumping more oxygen on than should be necessary for a neutral flame. You said:
Quote:
"When I couldn't get it to stop hissing, I turned it down to 8 and 4, but could only stop the hissing with a slightly reducing flame, not a neutral flame."
It sounds like you cannot get a nice bathing flame without going into reduction. This could be caused by that center candle being out of whack. It sounds like when you add oxygen to get a more neutral flame, you are pushing the oxygen harder to clean it up, getting a tighter, more aggressive flame and that is what is causing the hissing. Keep in mind, no torch is going to be absolutely silent. But, Bethlehem says, "On Bethlehem burners, loud noise does not indicate more heat. The soft, intense blue flame will bathe your work in heat..." So, even by their standards, the torch should not be hissing at the settings necessary for a neutral flame.

When your flame is set up to where it hisses and then you back it down to where it doesn't hiss, what do the candles look like? Are the outer five pretty even and neutral looking (or at least closer to neutral than the center)?

I suspect that your center candle is too uneven to get a nice neutral flame without adding excessive oxygen.

Of course, this is all just my guess based on what I've read.

You might want to call Bethlehem about this. If it is a brand new torch right out of the box (or if it has been thoroughly cleaned), and your center candle is significantly longer than the rest and is more yellow tipped than the rest, you may have a "bad bud" (defective torch).

About pressures...
It is the valves that control the amount of oxygen that gets to the torch jets. The more you open the valves, the more oxygen (flow and pressure) gets to the torch jets. The more pressure you have, the more oxygen you have available to feed the torch, and the more you turn the knobs, the more there is delivered. When the pressure is set high (like 20 psi), and you crack open the valve say a 1/4 turn, you are not getting that full pressure (20 psi) to the torch jets. When the pressure is set low (like 10 psi), you crack open the valve say a 1/4 turn, you are not getting that full pressure (10 psi) to the torch jets, either. You would have to turn that valve more than 1/4 turn to get the same amount of oxygen as you did before with the pressure set higher. The pressure you set at the regulator limits the amount of oxygen you have available to you. It does not mean that no matter how far you turn the valve, that is the pressure going to your torch jets.

So, running high or low pressures should not have anything to do with the torch itself hissing. It has to do with how much oxygen you are allowing to get to the torch jets through the valves. Even at a lower pressure, when you open your valve to let more oxygen in, it still hisses - you just have to open the valve a little more to get the hiss than you did when the pressure was set higher. And by the sound of things, you are having to add more oxygen than normal to get a neutral flame.
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Old 2006-08-21, 1:30pm
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Quote:
Originally Posted by bclogan

Which is complicated by the fact that the oxygen regulator that my husband picked out for me is a nice one, but it doesn't "do" low pressures on the gauge really well. The first line on the gauge is 5psi, and the first number that's listed on the gauge is 30, so it's kinda tough to really tell what it's set at. He thinks we can just change the gauge, I think we need a different regulator.
You know BC... I think your the one of the few persons that recognized the size of the regulator might be problematic.

I just wonder if some, perhaps many, of the tanked oxy-torch relatable problems we hear about, might simply be due to a oh-my-gosh big regulator that simply cannot properly control the oxy pressures we generally work at.

I've read that good quality regulators have a pressure guage installed that indicates the best psi range to use it - not directly indicates mind you, but just in a sorta off-hand way, i.e., that the middle 50% of the gage range is what the regulator is really good at controlling (droop and drop-wise).

For example: a regulator with a 0-30 psig gage would indicate the regulator is really good at controlling 7.5 to 22.5 psig; and a 0-60 psig gage regulator would be good for 15 to 45 psig.

Can anyone confirm this with real-life experience or welder education? (versus only what I've read from manufacturer materials).

Might help out on BC's next regulator purchase. (Oh... and mine too )

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  #9  
Old 2006-08-21, 2:29pm
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When I got my Pirahna back in Feb I had really difficult time getting a feel for it.

I figured out I was really overloading it. I run my oxycon full tilt and the propane at 2. I was used to my minor and running it at 4 or 5 and it was just too much pressure for the Pirahna. I do think I could get a hotter flame if I added a second Oxycon, but no more hissing and popping.

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  #10  
Old 2006-08-21, 2:36pm
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The regulator did not cause the center candle of her torch to be longer than the rest. The regulator did not cause the center candle to be yellower than the rest.

Pressure from the regulator is not the problem here.

The needle valves control the flow of gas and oxygen to the torch.

Think of it this way...

All of the larger two-staged torches Bethlehem makes have the Piranha as the centerfire, right? The Barracuda, the Tiger Shark, The PM2D and the Great White. They all have the same centerfire and it is the same as the Piranha. Well, all of those larger torches require higher pressures to supply them with oxygen, typically 10-20 psi. So, when you are working on one of these big torches and then decide to just use the centerfire for something, do you run over to your tanks and adjust your pressures? No, you just keep on working. Why? Because the needle valves control what gets to the torch jets. The centerfire of those big torches (even when set at 20 psi) will perform just as nicely as the stand-alone Piranha (even if set at 10 psi). The only difference is that the valves will be more sensitive at the higher pressure - meaning you won't have to turn the valve as far to get the same adjustment.
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Old 2006-08-21, 3:26pm
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Quote:
Originally Posted by kbinkster
The regulator did not cause the center candle of her torch to be longer than the rest. The regulator did not cause the center candle to be yellower than the rest.

Pressure from the regulator is not the problem here.

The needle valves control the flow of gas and oxygen to the torch.

Think of it this way...

All of the larger two-staged torches Bethlehem makes have the Piranha as the centerfire, right? The Barracuda, the Tiger Shark, The PM2D and the Great White. They all have the same centerfire and it is the same as the Piranha. Well, all of those larger torches require higher pressures to supply them with oxygen, typically 10-20 psi. So, when you are working on one of these big torches and then decide to just use the centerfire for something, do you run over to your tanks and adjust your pressures? No, you just keep on working. Why? Because the needle valves control what gets to the torch jets. The centerfire of those big torches (even when set at 20 psi) will perform just as nicely as the stand-alone Piranha (even if set at 10 psi). The only difference is that the valves will be more sensitive at the higher pressure - meaning you won't have to turn the valve as far to get the same adjustment.

I'm not saying the regulator is causing the problem she reported. I'm saying she recognized that the size of a regulator can have an effect... that the size may not be optimum for the purpose.

For me to be certain of my assertion, I asked for some feedback relative to regulator size versus good control.

Perhaps you are seeing the heart of the problem while I'm only seeing the periphery. I was looking at hissing. And if the regulator is soo big that a setting of say 10 is really like 20-40 psi (not saying for certain it is - just for argument sake) then perhaps the regulator could be contributing to the hissing? I don't get hiss at a true 10 psig. I do get hiss at true 20 psig, but I have never had to operate the Cuda that high. 10 pisg with lots of flow works really good for me.

As far as valves-pressure-flow, that's way too techincal, and takes way to much typing. I type way too slow to keep up (see how long it took me to post this?). I do agree the valves influence both. And are much more sensitive if the pressure is "up there".

But we could discuss tank flow and psig. Gobs of oxygen flows through the oxy reg at 10 psi. Gobs more than the Cuda could use. So all that's really controlled by uping the reg pressure is just pressure, because all the gobs of oxy are already available - just open the torch valve and let'em flow. But if the torch, or due to hose length, it needs more pressure to push'em through, then add more pressure. Do you agree?

Me
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  #12  
Old 2006-08-21, 5:06pm
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The only way I could see hissing being attributed to the pressure set at the regulator being too high is if there is a leak in the oxygen valve and oxygen is hissing through.

Where is the hissing coming from? If it is coming from between the valve needle and valve seat, then perhaps there is a leak there and higher pressure would create more of a hissing sound than lower pressure.

If the hissing is coming from where the flame comes out of the torch, then my earlier suspicion that she was compensating for a reduction flame (caused by a wonky candle) is probably right.

Or, in rare instances, there could be a large burr (left over from machining parts) in the valve body or a port that is causing the noise and it (the sound) can be carried up through the torch to the front, making a hum, whistle, or a hissing sound. It's a harmonic vibration thing that originates from one place and is tranferred to another. But, again, given the other clues in her post, I don't think that this is the cause of the hissing.

Back to pressures...

If the valves of a torch were marked like the dial on an infinite controller, with numbers ranging from 0-10, for instance, and say you have the valve set on "4" while your regulator pressure was set at 10 psi, you would have a certain flame and would probably not be getting a hiss out of it (and let's just say that you would have to turn it up to "6" to get a hiss). Now, if you were to leave the valve set to the same number, "4", but adjust the pressure at the regulator to 20 psi, then you will have a different flame and might be getting a hiss. You would be controlling the amount of oxygen getting to the torch jets (thereby controlling your flame) by adjusting the regulator pressure. Side note: This is what guys do with their Herbert Arnolds that have pre-set valves (HAs have very complex valves that are preset by the factory with one valve that the user can adjust to control the torch). They cannot change the settings of the pre-set valves on the torch (to change the flame characteristics pre-set by the factory), so they change the pressure at the regulator (in-line regulators make this easier).

Now, say your torch is still set at that 20 psi and you turn the dial down to "3" and you get that certain flame again (that you once had at "4" when the regulator pressure was set at 10 psi) and the hissing goes away. You have just controlled the amount of oxygen getting to the torch jets (thereby controlling your flame) by adjusting the needle valve setting.

So, the flame that once took turning the valve knob from 0-4 at 10 psi, now only takes turning the valve knob from 0-3 when you are running 20 psi. You can still get the same flame, but at the higher pressure, you do not have to turn the valve as far to get it. The valve control is more responsive at the higher pressure.

And to take the example further, with that torch set at 10 psi, you might turn the valve to "8" and reach a plateau where you cannot get a larger flame. And when you have the same torch set at 20 psi, you might get that same flame (that "8" would have given at 10 psi) at "6" and then be able to go on and achieve a larger flame at "8" and an even larger one at "10."

I still believe that the hissing in Barbara's case is due to the addition of oxygen needed to "clean up" a reduction flame caused by a center candle that is longer and more fuel-rich than the rest. At the lower pressure, she still got the hissing when she turned the valve up.
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Old 2006-08-21, 5:43pm
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Here are some pictures to illustrate my point (I apologize for the blurr - I didn't use a tripod and the torch is hand held). The photos on the left are all of the same flame at different regulator settings (5/2, 50/20. and 30/15). This required the valves on the torch to be set at different positions. I did not get any hissing for that small flame at the 50/20 setting . The one photo on the right shows the maximum flame at 50/20.
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Old 2006-08-26, 2:36pm
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I finally took my Piranha out of the box and set it up today. I bought it way back when Generations was having their close out sale. My candles are WAY uneven. Short on the left side, longer on the right side, but still WAY short, and the flame is really itty bitty...hot hot hot, but really itty bitty. Shouldn't the candles be even? and as far a neutral flame goes, with all of the candles even, I can't get it, the center one is always a bit longer, regardless.

I tried running the cleaning wire down it, and it did get "caught" a couple of times, but this was for naught. Should I run it and hope it evens out? or just hook the minor back up and send the Piranha back for repair? Does it need repair? or does it just need a new owner?
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Old 2006-08-26, 10:33pm
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There's definitely something wrong with it. This is a right out of the box problem - how could you have possibly done anything to it? There should be no obstructions to hang that wire up. I would send it in to Bethlehem.
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