Questions about torch gas and oxygen psi?
 

Hello,

This question could be applied to any glass torch out there but, I’m going to use the Bethlehem Barracuda as an example because it is the torch I got setup right now.

The recommended GAS is 3-5 psi and the OXYGEN is 10-20 psi.

So my question is if I have my Barracuda torch setup to one of the following settings below, what would the difference or advantage between the settings be?

How does this affect how the torch works or is used?

GAS – 3 psi
OXYGEN – 10 psi

Or

GAS – 5 psi
OXYGEN – 15-20 psi

Robert

Well, Robert, I see no one has attempted to answer your question, so I guess I will jump in here with my opinion/assumption. The only difference in 3/10 vs. 5/15 would be the ultimate output of the torch, were you to use it full open. Since most of us do not normally operate our torches full open, I doubt you would see much difference.

Pam is right because it is the needle valves that control the flow. A higher pressure will make your valve control more touchy. And a difference of just a couple of pounds would be hardly noticeable.

These Barracuda torch settings are recommended and were posted on bethlehems website.

GAS – 3 psi
OXYGEN – 10 psi

Or

GAS – 5 psi
OXYGEN – 20 psi

So the only difference between the low end of the settings (gas-3 / oxygen- 10) and the high end of the settings (gas-5 / oxygen-20) is that more volume of output used with the torches needle valves full open?

Also with higher pressure settings would make the needle valves touchier because more volume would be going through the valve with even the smallest turn?


Then the only other question I would have is why would anyone want to setup there Barracuda with Bethlehem’s recommended torch setting at the high end of their psi when there would be no difference except touchier control valves and more volume used if you have your torch full open?

Robert,
You would use the higher pressure settings so you could get more heat out of your torch--for example, I often use the higher pressure settings when I work boro. If you were making boro marbles, pendants, or anything sizeable it takes much less time when you have more gas pressure/fuel available.
If you're working soft glass, you would definitely use the lower of the recommended pressures.
Anita
www.fireflybeads.com

It is always best to have your regulators set on the highest pressure recommended, regardless of the glass you are using. That way you will have the gas (fuel/oxygen) there when you need it. Your needle valves control the flow. If you have your pressures set high, you can always control the flow through your valves and have as little or as much fuel or oxygen go to your torch as you need.

Here is an example of why you should not set up on the low end:

Say you are making a marble. You set out to make it one size, but it starts getting bigger than you anticipated. You need more heat. Now, if you are already set to the maximum pressures, you just turn up the heat by using your needle valves. But, if you were set up on the low end, you will have to go change the settings on your regulators to allow more fuel and oxygen to get to your torch.

There are many reasons why you would need higher pressures:

• long of lines
• multiple torches in line
• flashback arrestors in place
• elbos in a hard-lined set-up
• restrictions (e.g., hose connections, nipples, etc.) along the line

So, what I am trying to say is that you can never use less. You might as well start off with the highest recommended pressures given by the manufacturer.

The only torch I know of where you really need to change the regulator settings to get certain effects/colors out of glass is the Herbert Arnold. It has a single control knob and in order to finesse the torch, you adjust the pressures with in-line regulators (you could adjust them at the tank, but lots of guys put additional in-line regulators right at the torch so they don't have to run back and forth).

You do not need to run different pressures for different types of glass because you control the mixture and the amount of fuel and oxygen with your needle valves. Running low pressures for working soft glass is not only unnecessary, in the case with some torches, it will carbon them up pretty quickly. It is better to run them at the highest pressures you have available to you (within the manufacturers recommendation - do not exceed their valve tolerances) and to control the flow with your needle valves.

Oh, and when you set your pressures at the regulators, make sure that you go back and adjust them while your torch is running. If you just set your pressures, and then go to the torch and start working, the pressure will actually drop lower than what you set. So, you need to set your pressures, go light the torch, and while the torch is running, go back to the regulators and adjust them to the proper setting.

You can use the low end setting and get a more gentle flame. Fuel is not not rushing out due to high pressure pushing it. Anytime you up the pressure, it's got more push and will move more gas through the torch, regarless of needle settings. It all depends on your working style. Some soft glass artists like a softer flame. For boro, I like a fast flame. I want the push and maximum heat. This is exactly why I like the Beths for a cross over torch. It can do both very well. ;)

"Anytime you up the pressure, it's got more push and will move more gas through the torch, regarless of needle settings."

When you increase the pressure at the regulator, you increase the amount of gas available to your torch. Your needle valves are what regulate how much gas actually gets to the torch from the lines. I'll use oxygen pressure (from a tank) as an example - it works the same for fuel, as well. The numbers are just for demonstration purposes. Say you have 20 psi coming out of the oxygen tank and through the line (this is what Bethlehem recommends for the high end pressure), once it hits a closed valve, it stops and no oxygen is getting through the torch. If you crack open the valve (say 1/16 of a turn for example), you are only getting so much of the oxygen through to the torch. If you open the valve all the way, you are getting all of the recommended oxygen to the torch and can get everything out of that torch. When you have higher pressure in the line, you turn the valve in smaller increments to increase or decrease the amount of oxygen coming into the torch. Your control is touchier, but you have a broader range. You can go from completely closed getting no oxygen to completely open getting as much oxygen as the manufacturer recommends - the full 20 psi - and everything in between.

Now, say you set the pressure to 10 psi. When the needle valve is closed, there is no oxygen getting to your torch. When it is cracked open (say that 1/16 of a turn used as an example), there is some oxygen getting through to the torch, but only 1/2 as much as if you were running 20 psi. If you were to open the valve all the way, you would only get as much oxygen as the regulator alllows, and in this example that would be 10 psi, or half of what the manufacturer says you need to get everything out of that torch. You will have to turn your valve in larger increments to increase or decrease the amount of oxygen coming to the torch. Basically, you would have to turn the valve 1/8 of a turn at a regulator setting of 10 psi to get as much oxygen as turning it 1/16 of a turn at a regulator setting of 20 psi. Your control is less touchy, but you have a narrower range. You can go from completely closed getting no oxygen to completely open getting only half the oxygen as the manufacturer recommends at 10 psi and everything in between, but nothing more.

Some people like touchy controls. Some people don't. Some people like them for some applications, but not for others. This is where personal preferrance comes in. But, the fact remains that the needle valves do control how much of the gas from the lines gets through the torch. The regulator pressure only dictates the upper limit.

PS There are days that I switch from working soft glass to working boro. I work with my pressure set to the highest recommended setting when I'm on a tank. I just turn my valve knobs up more to push more oxygen and propane through my torch. I don't ever get up to change the regulator settings.

Thanks for everyone’s reply.

I have another question. Do you think something is wrong with my new regulator? I bought a new gas regulator for my propane tank because my old one only had 1 gauge on it that allowed me to set the output psi.

I bought a new regulator that has 2 gauges on it one to set the output psi and one that tells me how much propane is left in the tank.

Well to day while on the Barracuda I noticed that after setting my propane to 3 psi the gauge needle with go up and down depending on how I adjust the torch flame.

For example, with a neutral flame my regulator gauge reads 3 psi. When I change my flame to a micro pin point flame the regulator reads 5 psi, and when I change the flame to a reducing flame the regulator gauge reads almost 0 psi.

Is this normal? I thought it might be the Barracuda so I connected my GTT and the regulator goes up and down in psi with how much I open and close the gas valve.

Thanks again,

Robert

It is normal for the gauge to do this because you are relieving pressure in the line when you open the propane valve. The higher the pressure setting, the less noticable the swing will be.

A better regulator will a hold more stable pressure. Work with it and see what settings work best. Getting new equipment is always an adjustment. I've seen studios operating on pancake regulators... it's all in what you can afford and get used to. :D

The pressure settings on the regulator do dictate the rate at which the fuel flows through the torch. Of course you can adjust the amount of fuel with the needle valve, but at higher pressures, the gas is moving faster. That is how you get a driving flame. If you want a soft flame, the pressure on the low end is best. This elliminates the woosh or high pressure push through the needle valve and allows a softer flame. ;)

No way. The regulator I bought was the best you can get, I upgraded from a cheap regulator. Now it is not a 2 stage regulator but it is a solid 1 stage regulator.

I just thought that when you set your gas regulator at X psi it is supposed to always stay at that psi regardless if you have your torch is closed, half open, or wide open.

I see where you are coming from with your reasoning, but it just doesn't work that way.

I'll try to explain it with an analogy.

Say you have a water spigot at your house. The water pressure is regulated and set to 40 psi. When you turn open the spigot a little, you get a trickle of water.

The water company comes along and increases the water pressure to 80 psi. When you go to crack open the spigot, you do not have to turn it very much for the trickle of water to start coming out. That trickle of water is still just dribbling out the same as it was before. The water is not shooting out of it any faster than it was at the lower pressure.

Next, the water company comes along and turns the water pressure down to 20 psi. You have to open the spigot more than normal to get the trickle of water. The trickle is still trickling. It isn't moving in slow motion or anything. You just had to turn the valve more to get it to come out like it did before. Now, if you open the spigot valve all the way, you might feel frustrated because there just isn't enough water coming out. The low water pressure limited how much water could get to the spigot.

The valves on a torch work the same way. The valves control the gas that goes to the torch. Once the gas reaches the needle valves, they take over.

So, if you want a soft flame, just keep the regulators set where they are and use the valves turned on a little bit (the valves will be very responsive when using higher pressures). Unless, of course, you like to turn your valves further before seeing a response in the flame. Then, by all means, set the regulators to a lower pressure.

This may be helpful...

http://www.arrowsprings.com/html/tips___tricks.html

Open this up and look at the bottom of page 3 (of 14), particularly the last two paragraphs (well one of them is just two sentences long).

The Arrow Springs guide is a wealth of information.

PS

I found the same thing here in the last two paragraphs of the page:
http://www.arrowsprings.com/html/con...egulators.html
So, you don't have to download the pdf file unless you want to. Here is what it says about pressure settings:

Just try to explain that to those guys who have to be "ragin" their torches with the oxy turned up to 60. Never did understand that. Lack of education in basic physics, who were Venturi and Bernouli anyway?

-Don-

Kimberly, Thanks again for giving such succinct answers to these questions. I've always known that pressure regulators fluctuate while using them, unless they are two-stage, but never really understood specifically why. I knew vaguely, but now it makes more sense.

Yeah, who were those guys? :lol:

Don, are you going to AGI again this year? I think I remember you saying you were. It will be great seeing you again. I've still got to book my flight. Nothing like procrastination... :D

Google Venturi Effect and then check out the Bernouli effect.

It's more than I want to discuss as it applies to torches, before coffee. :D

The water at the higher pressure is coming out faster. There is an increase in velocity through the reduction point. This is increased by the amount of pressure behind the reduction point. The only reason water will run out as slow as the first trickle in your annalogy, is because it's hitting metal before it comes out. If it didn't hit metal and slow down, it would squirt very far and fast... much farther and faster than the 40 PSI line. This is the way a pressure washer works. Sorry Kimberly, but pressure in the line has everything to do with how fast the gas moves out of your torch face. It creates the woosh sound you hear at higher pressures. To say it doesn't make a difference, by comparing it to a sink experiment is just plain silly. Read some stuff on Physics and stop playing with the hose. ;)

Thanks Kim your answers make sense.

So in theory you could set both your gas and oxygen psi to the same at 20 psi. Then your control over you different flame characteristics is controlled buy your torches valves and how much gas or oxygen is let through by opening or closeting your torch valves.

Yeah, set both to 20 PSI and let me know how adjusting them at the torch valves works out for you. :lol:

Yes. The only thing that will happen is that your valves will be touchier and you won't have to open them as much to make the change. Now, this assumes that you do not have sloppy valves.

If your valves are sloppy, you won't have the control to finesse the torch at higher pressures.

Just quoting for prosperity... want to make sure this statement hangs around. :D

You are right that the valves will become touchy... but it's not the only thing happening. ;)

A torch and its valves makes up a system of twists and turns, restrictions and openings. It is not just a straight shot through from the lines to the face. The valves, themselves are more than simple restrictions.

O.K., then, what is a regulator, anyway? It is nothing more than a complicated valve. Oxygen in a freshly filled tank is at about 2000 psi. According to your reasoning, once the oxygen passes through the valve (the regulator) to the line, the amount of oxygen will be less than if the tank valve were wide open, but it would be coming out much faster at 2000+ psi. If the pressure going through the torch has everything to do with the pressure in the lines (the pressure set by the regulator), then the pressure going through the lines has everything to do with the initial pressure set (the pressure in the tank). Fortunately, it does not work that way.

What "woosh" sound are you talking about, btw?

Actually, I have read stuff on Physics in my day. I am not a physicist, but I did take two years honors physics in High School and I took a little physics in college, as well (I have a minor in Astronomy, it required a few science classes). But a person does not need a science background to understand any of this.

Are you planning to profit from my quote? Or, did you mean to say "posterity?"

I meant posterity. :D I doubt anybody could profit from your quote...

A simple valve is not the same as a regulator... if it was, by your reasoning... we wouldn't need a "regulator" at all. Just a simple innexpensive valve. Hey, there is already on on the tank... skip the regulator, put a few twists in your hose and let me know how that works out for you. :lol:

I never said a regulator was a simple valve. I said that it was a complicated valve.

What's up with the insults? You've said that my analogy was silly. You implied that I knew nothing about physics when you told me to read some stuff on physics. Now, you are saying that no one could profit from my quote, implying that it is worthless. Well, all knowledge has value - even if it is just the knowledge that something can be done.

I have been kind and respectful (to you and everyone else) in my responses to this subject. I have tried to explain things so that they could be understood. Even though you are not yet grasping what I have explained, you don't see me calling you any names or implying anything about your intelligence.

I grasp what you have said... I am just saying it's too simple of an explanation... and it's not taking more complex properties of gas through a valve into account. I don't think you are grasping what I am saying. It's got everything to do with how increased velocity due to pressure effects the flow of a gas. I told you to read more on Physics in the hopes that you could understand where I am coming from more completely. You are right, knowledge is valuable, but only if it's correct. I think if you look into this a little further than you have, you'll see that there is more here than your simple explanation covers. The pressures you run a torch at are very important. There is certainly a range and every person will find a setting that works best for them and their style... but to say you can adjust everything at the torch and to set it at the highest point in the range is wrong. It's not that simple. ;)

Think of it this way...

If you have a high line pressure, the needle valve can adjust the amount of gas going through it. What it does is let a smaller amount of gas pass with a higher velocity. This fast moving gas goes into the Manifold. This highly excited gas is going to move through the torch differently than a slower moving gas. It creates eddies and can create a vortex. This chain reaction does follow the flow through the torch and has an effect of how the torch opperates. All of this can be harnessed by torch design and used to bennefit us. A slower moving gas through the torch can produce a softer gentler flame. Sure, the valve needs to be open further to get the same volume... but the excited state of the gas is different. It's less intense. All torches have an operating range based on these properties... the lower range does have advantages... and that's all I'm trying to get across. ;)

So what your saying is if I have a garden hose and water running through it at 20 psi the water stream will look like a limp urine stream.

If I put my finger over the hose opening it will still be pushing the same volume at the same psi through a smaller opening and the urine stream will shoot out further and harder?

Kind of, but not really... you are getting my point a bit.

The volume is changed by putting your finger over it and restricting the flow... the pressure in the hose determines how fast the water goes through that restriction. The higher the pressure, the faster the water moves through the same sized space. This increase in pressure is directly connected to the increse in velocity. Thus making the water shoot further. Now, if you fill a bucket with that hose, you can see the vortex and eddie effects I'm talking about. The bucket represents the manifold inside the torch. You can fill a bucket gently with less pressure and a bigger openeing just as fast as you can fill it with higher pressure and a smaller opening. The volume doesn't change, but the way the water reacts when it enters the bucket space is totally different. One is excited and the other is relaxed. It's night and day inside a torch manifold as well.

Now you've got me explaining this with a hose, a bucket and water... damn, I can't beleive you got me to play with the hose idea! :lol: Thanks Robert. :lol:

You know you love it.

So how would these different psi settings affect the flame?

Would you only get a harder driving flame or would the flame be hotter?

The flame is going to be it's hotest when a balance is acheived. When the right amount of both fuels mix efficiently. The flame characteristics are different at every setting. When one thing changes, everything changes. There is a specific setting on every torch that will produce the most heat. Adjusting pressures and valves will give you an endless variety of flame characteristics (reducing, neutral, oxydized, soft, driving... etc). The sweet spot is different for every torch and what works best is not always the hottest... and what creates the hottest flame on one torch certainly won't be right for another. I am just now finding the real sweet spot on my Cuda. It's so hot I can't believe it. It's totally diffent than a super hot GTT flame. It sounds different and it looks different. Play with it and find what works. The specs by the manufacturer are guide lines and a great starting point. Your guages may not be calibrated to the same specs as theirs... It's all fun and if it was super simple, it wouldn't be half as interesting. :D

A picture is worth a thousand words. Here are some photos of a soft flame at three different pressure settings and one picture showing a big flame on higher tank pressures - what limits the upper end.

The torch in the photos is a GTT Lynx (handtorch). The diameter of the face is 3/8". I have labeled the regulator pressure settings on each photo.



As you can see, you can get a very similar flame, regardless of the regulator pressure settings. The needle valves control the gas going into the torch.

Can you demonstrate that with a bench torch... say the lynx, the Phanton and a Mirage? The valves are so far from the ports on that hand torch, that it definitely calms the turbulence created by the valves choking the fuel. Remember that distance play an important part as well. ;)

Kim, that rocks! Hard to argue with those pictures.

Whose arm is in the picture?

Hey is GTT making any new torch models? If so I’d suggest the Delta Mag Jr, Lynx > Phantom > Mirage.

Then a super duper Lynx, @ stage Lynx with 1 port center fire.

Just showered... I'm squeaky clean... congrats Kim on finding one little flame on a long arse torch to demonstrate your point. Can you show us how the larger soft flames can be produced with high pressures as well? I know there are glass workers that use a larger soft flame for soft glass. I'd like to see one that isn't a little short thing. My point never was that a soft flame wasn't possible at all with high pressure... My point is that high pressure can adversly effect the ability of a torch to make a soft flame... size matters here. The turbulence in the gas is increased with volume. Make a medium and large sized soft flame with your torch on high pressure. :D The bennefits of backing down the regs has a range as well. Not all flames can be made with one setting and that is my point in it's entirety. :D

Oh, for crying out loud. This happens to be the torch running on a tank right now, so this is the torch that got photographed. You can get the exact same flame out of a Lynx bench burner - or the centerfires of a Phantom, Mirage, Delta Elite, Delta Mag, Cobra, or Python, for that matter. If the flame on the hand torch were different than the flame on a bench burner, then they would have to call it by another name, now, wouldn't they?

You should be able to get a similar flame on any of the surface mix torches out there at various tank pressures, provided the valves are decent. I would not try the 50 psi oxygen/20 psi propane flame on the Bethlehem Barracuda only because they say not to use pressures higher than 25 psi with their valves.

Are you saying that you cannot control the flame on your Barracuda at higher tank pressures? If this is the case, then it sounds like there could be a problem here with the Bethlehem valves. From what you are saying, the valves seem like they are not able to control the flow precisely enough at the higher tank pressures. Otherwise, you would definitely be able to dial in a similar flame to the one I photographed at a higher tank pressure or a lower tank pressure.

The flame I photographed at 50 psi oxygen/20 psi propane (from a GTT Lynx hand torch) sounded exactly the same as the flame at 5 psi oxygen/2 psi propane. There was no whooshing sound. You mentioned hearing a whooshing sound from your Barracuda when you run higher pressures. Is this an inherent problem with all Bethlehem torches? Or, maybe there is something going on with your valves, like a burr(s) in the valve orifices, causing the excessive noise you are experiencing at higher pressures.

I'm not attacking Bethlehem here. It just happens to be the torch you are using and getting these "symptoms" from. It sounds like your valves are not "precision" enough to control the flow of gas and oxygen at higher pressures, in my opinion.

As far as the other stuff...

You are looking at a manifold as if it were a bucket. Buckets are big empty chambers. Manifolds are not. Manifolds are a series of channels that direct the fuel and oxgen to their proper ports.

Sure, when you restrict an opening so far, it forces that gas to go through harder. But, there is a point where it no longer makes it go faster, it actually makes it slow down.

What ever works for you Kimberly. I would have no problem working a Cuda at higher pressures. They don't suggest it because of bad valves... they understand physics and the increased pressure if out of the range for useful flame characteristics... :D

That is Willy's arm in the picture.

Once you know how to control the flames, the Mirage can imitate the Phantom flame. So, I don't think they will be making the Delta Mag, Jr.

GTT has made single port torches. Al Janelle has one and calls it his "cheater torch." He uses it in addition to his regular torch.

Try getting the needle flame on your centerfire by running the red and blue valves only. You can get a tiny flame that is small as the smallest tip on a Smith Jewelers' torch.

Well, their operating instructions clearly state:

"DO NOT EXCEED 25 lbs. pressure on any feed. Excess pressure may cause gas or oxygen to leak through the valves and increase the chance of leakage through the hose connections."

That is why I said that I would not run the Barracuda at 50 psi oxygen and 20 psi propane.

I guess they like having information on their site and what company doesn't cover their butts when it comes to liability? I can't wait for the new quad mix torches... those are gonna be sweet. Even more control over combustion and efficiency. :D

Hey Kim,

I'm seaching google right now, but do you happen to have a picture of the "cheater torch"?

I'm looking at some of Al Janelle is his work is amazing.

So if I wanted GTT could make a Cheater torch for me? It's just not something they are going to ever go into production with.

That might be cool but like microsoft windows, I'm sick of new versions coming out every 2 years.

Is Bethlehem at least going to offer 4 stud options?

If I was judge keeping score I have it 2 to 1 in favor of kbinkster.

Oh, so "Turning the precision needle valves easily changes flame settings" is really there to "cover their butts?

Of course the needle valve changes the flame settings... duh... and no, I never said that statement was made to limit liability. Are we having the same conversation? :-s

It was in response to:
See, this is why I prefer using quotes and addressing issues one-by-one.;)

That was right after you questioned the reliability of their valves... nothing was said on my part about "everything" on their site being part of limiting liability. Sheesh. This has become tired and since we aren't going to stay on point... I'll retire from the conversation. Maybe you should call Henry Grimmet and tell him he should change his lecture on how gas pressures determine how a torch operates... as a matter of fact, there are several people you should contact and show them the light of your wisdom. A whole crap load of experts have obviously got it all wrong. :lol:

I was wondering if you got that notion about changing pressures from Henry.

Henry has been warned about this, and he said that he stopped putting that out. So, he's still saying this, huh. Thanks for the info.

The reason he started putting that out was because his colors are sensitive to reduction. When he first used a GTT torch to work the colors, he said that it was just perfect for them. Then, people started accusing GA of having some sort of deal with GTT to try and monopolize the glass industry since the GTTs were the only toches that could run GA colors. So, to make his colors work well for other torches, he came out with his theory. The standard torches out there will go into a reduction flame rather easily when trying to get a big flame. The valves are not "precision" enough to fine tune the flame at higher pressures. So, in order to better control the valves, and make them more forgiving, you need to lower the pressure at the tanks. Higher pressure will make the valves touchier/more responsive. Lower pressure will make the valve less touchy/less responsive, allowing a greater margin of error. Those torches need that forgiveness when running the big flame, because the big flame is what can slip into reduction easily, not a little flame.

This does not apply to GTTs, as their valves are very precise and they (the GTT torches) just operate differently - and it does not apply to other torches when running a regular flame for soft glass, because you do not need that big flame like you do with boro.

There are applications where you would benefit from having more or less responsive valves. But, the fact remains that the needle valves control the gas that goes through the torch.

EDIT:
"A whole crap load of experts have obviously got it all wrong."
Arrow Springs didn't get it wrong.