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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2013-01-24, 5:50pm
Talonst Talonst is offline
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Default Experimenting with Compressed Air

For the past few months I've been working on using compressed air through my torch - turns out to be easier than you would expect to set up and worth the effort. The picture below shows a Mega Minor running compressed air with propane a 4 psi, O2 at 15 psi, and compressed air at 20 psi

Why, you ask, would I want to do this?
- It provides another range of flames and chemistries with the torch you already have. This translates into new capabilities and benefits including less boiling and scumming of clears (or crayon colors in boro), greater stringer control and a more even and adjustable heat - particularly useful in murrini-making, florals, encasing, and on larger surface mix torches in hollow work where the qualities of this type of flame provide a more uniform heat that makes blowing easier
- Turns out it saves O2 as well. I'm seeing perhaps 20-30% additional time on a K tank of O2 running a small torch and working soft glass. Your torch, oxygen source and working habits are all variables so your performance may be different
- Can be used on any surface mix torch without modification of the torch
- I suspect this would also work well with concentrators - but I haven't tried that yet

Still interested? - Keep reading . . .

Back in June of last year I took a week long class at Corning on soft glass montage with Andrea Gutgesell. Toward the end of that class I had the opportunity to work on Andre's Thüringen model torch which uses compressed air - it was amazing to me how controllable the heat was. From that point on I started wondering how I could modify my own torch to achieve some of the same benefits. After some searching I found Jason Howard's article in Glassline - Advanced Torch Paradigms (Volume 25, number 1, pg. 48 ). In this article he discusses the benefits of using compressed air and the way in which he does it. The article is worth the read and you can find the text of it over on talkglass or if you subscribe to Glassline you can download the article from the back issue section on their website

For the smaller torches I run I thought that using independently regulated gases at the bench the way Jason describes was more than I wanted to tackle. What I was looking for was most of the benefit but with a simpler setup appropriate for my needs.

(Continued in the next post)
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Last edited by Talonst; 2013-01-24 at 6:45pm.
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  #2  
Old 2013-01-24, 6:12pm
Talonst Talonst is offline
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Default Experimenting with Compressed Air - Test Rig

This picture shows my test rig. This has been replaced by a new build which I'll show later but because of it's layout it's easy to see what's going on. There are also a couple of issues I'll point out along the way

Before continuing, some warnings.
- If this looks alien to you - don't do it. You should be familiar with your torch and have plenty of experience with it before you get into this type of thing.
- Introducing air into your torch creates another set of variables and flame types so there is a learning curve
- The compressed air is introduced into your gas line NOT THE O2 line. Compressed air can contain compressor oils and other foreign matter that won't play nice with oxygen. Remember O2 and petroleum (gas, oil, plastics, rubber) = YOU having a VERY bad day
- All of the air connections use teflon tape for sealing or you can solder them. All the gas fittings DO NOT use teflon tape. Gas fittings seal when the male threaded part bottoms out on the back of the hose nipple or fitting. If a gas fitting leaks when tightened it's bad - dispose of it - don't use tape or sealing compounds
- This probably isn't sanctioned by the torch manufacturers
- Only you are responsible for taking on this project and it's results

So now we can move on, starting on the left is the compressed air quick connect and then an in-line regulator. After the regulator is a ball valve and then a transition section from the 1/4" air fittings to the b fittings on the propane y-connector. Air comes in from the left, propane from the bottom and the resulting mix exits to the right out to the propane port on the torch. All inlets and outlets use quick connects

One thing I did wrong with this was the section of clear hose - that needs to be T-grade welding hose since it can come in contact with the propane gas.

I also discovered that the in-line regulator I used (this one is from Lowes) is really just a needle valve and so the pressure reading fluctuates as you adjust the gas valve on your torch. This makes it hard to know how much air you're running through. I also decided that I should have a water/oil trap to catch any contaminants in the air so as not to clog up the ports on the torch over time. These observations led to the next build

(See next post)
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Old 2013-01-24, 6:20pm
Talonst Talonst is offline
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Default Experimenting with Compressed Air - Rig V2

This is the current build. The piping is a bit more complicated but it's really the same as the previous version but I've added a proper air regulator with an inline water/oil trap and have corrected the hose issue. It's also mounted on a backing plate that I can clamp to the bench.

You can see in this picture the air hose (coiled yellow hose) and the propane hose coming in on the left with the hose going to the torch exiting to the right.

If you've been lamping a while you may have a lot of parts kicking around for this project. There's probably $150 worth of parts and fittings to this rig. You'll also need a small pancake-type compressor with a couple of gallon holding tank - the type typically used with nailers or small spray guns

In the next post I'll talk about the startup sequence . . .
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Old 2013-01-24, 6:41pm
Talonst Talonst is offline
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Default Experimenting with Compressed Air - Startup

Typically when you start a premix torch you adjust the propane flame to be about a hand length with the flame attached to the face of the torch and then you add oxygen to get it neutral. The startup with air is similar but more propane is needed to offset the air and the oxygen is used initially to stabilize the flame.

I start with the air valves on the air rig closed and the propane valve at the y connector fitting open. The first picture shows the starting propane flame - about 12". What I'm looking for is a flame that's not attached to the face as in the second picture. At this point add oxygen until the bottom inch to inch and a half glows a nice bright blue and the flame is stable an attached to the face of the torch.

Now the air is introduced. Back on the air rig open the ball valve and then very slightly open the needle valve on the y-connector. Too much air too fast and the flame will go out. It takes a little practice to figure out how much air to add. There's a delay from the time that you turn on the air until you see it's effect in the flame - The delay is related to the length of the hose from the end of the y-connector to the torch connection - a shorter hose will reduce the delay.

I add as much air as I can without blowing out the flame and then fine tune by adjusting the propane and oxygen for neutral. This is the baseline flame. From here add oxygen for more heat or reduce it for a cooler or reducing flame, or add more propane and O2 for a larger hotter flame.

If you're running an over and under (torch with a premix rider) or a torch like a Carlisle that has a premix center you won't use the air with the premix - just shut it off and run the premix with O2 and propane only.

I currently have a set it-and-forget it approach with this small torch when using soft glass. If you have a torch that's capable of a very tight, small flame you probably would turn the air off for that. I'm also loving using the air with larger surface mix torches for making boro marbles and working with crayon colors where it's great for setting up linework on tubes and blowing. For large boro gathers where more heat is required I shut the air off and run the torch normally

I hope you all try this out - it will be interesting to see what other people's experiences are.
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Last edited by Talonst; 2013-01-24 at 8:41pm.
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  #5  
Old 2013-01-24, 7:07pm
dusty dusty is offline
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This looks awesome, thank you for posting.
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  #6  
Old 2013-01-25, 7:16am
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Only concern I see is the yellow poly line that feeds the compressed air... Friend of mine had a line like that explode into hundreds of tiny pieces, unfortunately he was in neat proximity of line and he took the hit and had hundreds of small bruises all over his body and arms and legs....After seeing the damages, I no longer trust these type of lines.... What caused line to explode we do not know, and it really does not matter, they are not to be trusted after seeing the results....

Dale
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  #7  
Old 2013-01-25, 7:43am
Talonst Talonst is offline
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Good point Dale. I can see how the plastic might become brittle over time from repeated flexing. At the moment I'm using it as a temporary hook up until I can extend my hard plumbed lines to my glass bench. Since this is all relatively new I wasn't sure whether this type of setup would provide enough benefits to justify a permanent line.

Thanks for your comments - I appreciate the feedback.

Last edited by Talonst; 2013-01-25 at 7:46am.
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  #8  
Old 2013-01-25, 1:10pm
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cheng076 cheng076 is offline
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Herbert Arnold torches have had air injection for a long long time. I read the mentioned articles and was tempted to try it but haven't gotten around to it yet. Very interesting post and good job setting it up.
PJH
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Old 2013-01-30, 3:26am
GlassAlias GlassAlias is offline
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Maybe I missed it but what psi do you end up with for the compressed air after your done getting your flame just right?
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Old 2013-01-30, 3:28am
GlassAlias GlassAlias is offline
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@ Dale - Was your friends poly line braided? I can see how a non braided line might explode but if it was braided it should have just kind of popped at the weakest spot.
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Old 2013-01-30, 5:21am
fsankar fsankar is offline
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Do you get enough heat to do Boro? Nice pics. Thanks for sharing. Since it works I can now justify buying a compressor instead of the oxy conc.
Franklin

Last edited by fsankar; 2013-01-30 at 5:24am.
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Old 2013-01-30, 6:15am
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Quote:
Originally Posted by fsankar View Post
Do you get enough heat to do Boro? Nice pics. Thanks for sharing. Since it works I can now justify buying a compressor instead of the oxy conc.
Franklin
The compressor won't make your torch run hotter. It basically make the flame less harsh and more versatile. If your current setup is lacking oxy, you still need that oxy con, or tank.
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Old 2013-01-30, 6:53am
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Coming from the neon background, forced air and gas torches are nothing new. I made my first beads in a 7 point crossfire. A 7 point crossfire is also what I learned my soft glass blown work on. Back in the day when I was doing production work, I would bleed a little oxy into my lines to make my flame hotter and speed my melt times. I used forced air, not compressed air. I needed a high volume at a low pressure, not high pressure at a ,low volume like compressors. A compressor could not keep up with what I needed and keep a steady pressure. For my neon shop I used a spa blower, or a whole house vacuum motor, run backwards with a holding tank and a relief valve. That way I wasnt putting a lot of back pressure on my motor. I replaced my brushes in the whole house vacuum motor every 4 months or so. thats running 10 hours a day or more( this will run a 3 man neon shop). For a small home system for a single torch set up, I used a kirby run backwards, and a holding tank set up and relief valve. The holding tank actually was not to hold a volume of air in reserve, it was to reduce the flutter in the air flow direct from the source. I had a "dog house" outside of my work space to reduce the noise in the shop and protect it all from the weather. My relief valve was home made with basic PVC pipe fittings and large washers were used as weights to adjust the pressure. I used one of those red tanks you get at home depot to store compressed air in,my husband uses one to fill car tires and beach toys, blow off something etc etc, they are not expensive.
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Old 2013-01-30, 9:03am
Talonst Talonst is offline
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To Glass Alias - There's really no easy way to know what the actual pressure is at the torch since there are two valves (1 at the y connector and the other on the torch) between the regulator and the torch face. I'm guessing it's around 10-15 psi. What is important though is that the pressure is set such that it's no too high that it blows out the flame or requires so much propane and oxy that you end up with really long candles. The startup sequence I show is to establish the typical small torch flame with 3/8" candles - but there are other things that you can do with compressed air - like create larger bushy flames that you would use for 104 tubing

Check out this video link to see the Thüringen torch in action:
http://www.youtube.com/watch?v=sCq-xhwICF8

To fsankar - The air cools the flame as shawnette mentioned so I tend to use it for crayon colors if I don't want to encase them or when I'm setting up color for an implosion marble to keep the color from boiling and spoiling the clear - also nice for putting color on tubing or working thin walled tubing to slow down the heat and provide a bit more control. Otherwise I run the torch normally without the air for most everything else in boro.

I had an opportunity to take a class with Shane Fero last summer and saw how he used the crossfires for his work - I think he was using one of the japanese style air pumps to run them. He uses a Carlisle to apply the frit and do the basic shaping of his birds and the uses the crossfire for the details like the beak, eyes, and feet

Just to clarify compressed air is not a replacement for oxygen - So you'll still need an oxygen source. The upside is that while using the compressed air your oxygen use will tend to be somewhat lower.
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Old 2013-01-30, 1:09pm
fsankar fsankar is offline
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Thanks Shawnette and talonst.
I guess there is no free lunch.
When I saw the experiment above. I was thinking about making a well insulated mini gloryhole for the air driven torch. But I am afraid that it may burn out the tip of my torch. Maybe make a mini gas train like the hotglass people use and use a pipe for the nozzle. Suspect I wont get it hot enough for Boro.
Franklin
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Old 2013-01-31, 12:03am
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There is a great article about this in Glassline. It is great for making a GTT with an aggressive flame softer for working with tubing and crayon colors without damaging the torch.
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Old 2013-01-31, 8:14am
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Quote:
Originally Posted by GlassAlias View Post
@ Dale - Was your friends poly line braided? I can see how a non braided line might explode but if it was braided it should have just kind of popped at the weakest spot.
Was one of those plain coiled, stretchy poly lines (non braided probably Chinese in origin)....

Dale
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Old 2013-01-31, 9:19pm
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I use crossfires and oxy air propane about 10 percent ox is added to the mix by a venturi mixer body. The ox gives more of an oxidizing fire as opposed to reduction. The crossfires heat the glass from both sides making things much quicker to work with. 1 psi ox to 10 psi of air. The atmosphere only has about 23% ox. Needless to say this cuts down on the ox cost big time. This is a soft glass set up. Borosillicates and Quartz glasses require oxigen and no air. Some high temp glasses may also need hydrogen to even melt them.
One of my favorite torches was made in the 1930's and handed down. I was made in the 1940's
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Old 2018-12-30, 1:26am
MickeyTT91 MickeyTT91 is offline
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Default Compressed air

Something I found that works quite well, instead of using an air compressor which can potentially introduce oil to the flame/oxygen, using an Svn breathing machine that asthmatics use to do breathing treatments. It doesn't use oil, and it has it's own filter that collects dust,water, or oil . It pushes an adequate amount of air pressure which you can T directly to an oxygen concentrator, it makes it virtually identical to the amount of uhmph you get from using tanked o2. Plus, they're quite cheap, especially in comparison to the cost of an air compressor. If you T it directly to the oxy hose, just put the concentrator on the bottom of the T with the Svn nebulizer adjacent. Light as normal, slightly rich on propane, if you use a T with a dial, open the whole T while lit, the flame will dial back slightly, then flick on the nebulizer and adjust as needed.. hope someone gets use of this, I have
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