# Thinking about making an oxy-hydrogen system for use in the shop.



## Kaleb (May 26, 2010)

I have been told by some people at a welding course that an oxy-acetylene system is so much better for silver soldering than my air-LPG torch which I currently use for soldering and annealing copper, but oxy-acetylene is expensive! $300 for the equipment package, and an extra $250-300 for the yearly cylinder hire, and an extra $100-150 or so in gas levy per year to boot!  I just can't afford such a system. So I thought, why not use hydrogen instead? I did some reasearch, and I found they use oxy-hydrogen for underwater welding, (It gets up to 2800 degrees celsius!) and I can easily generate both gases from water using electrolysis. Instead of pressurised cylinders, I intend to get the pressure needed in the torch by using a pair of electric pumps. The torch itself will be similar to a regular oxy-acetylene torch. I also intend to make a flame cutting torch at some point as well. I've attached a diagram of the electrolysis cell and torches I intend to make.

If the pictures look funny, just click to enlarge them.


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## tel (May 26, 2010)

An ambitious undertaking Kaleb, tho' I suspect that the cost of electricity to generate useful amounts would cost as much, or more than the cost of conventional O/A. Then there is the heat loss you will have - Oxy/Acet generates, from memory, something like 3200°C - a 400° loss.

You might be better looking at generating acetylene from calcium carbide - it must be still available as the banana growers ripen bananas with acetylene made in generators. Comes, I am led to believe, in 20kg drums.


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## Florian (May 26, 2010)

Its also possible to use propane and compressed air! 

I use an airbrush-compressor (much too small actually) and a 5 kg propane bottle to solder. If i don't need much heat, i just use propane.

When soldering boilers or when i want to heat up very quickly, i open the air valve and then i have more heat. I have even made a new jet with a bigger bore for soldering with air. 

Cheers Florian


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## shred (May 26, 2010)

Jewelers have little electrolysis Oxy-Hydrogen setups for doing metals that oxidize poorly, but for some reason they're very expensive and have very small flames.  I suspect you'll need a whole lot of H2 production to heat anything reasonably large.

Florian's setup looks interesting-- can you post some more details?


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## IronHorse (May 26, 2010)

A few years ago I got one of those portable Oxy/Ace units for work on my car. They are convenient because you own the tanks. The tanks are only 14" long, but hold a fair amount of gas. Works perfect for silver soldering with a small tip.

http://www.harborfreight.com/portab...cpc&zmam=13262200&zmas=12&zmac=112&zmap=65818

IronHorse


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## bucketboy (May 26, 2010)

I've used oxy-hydrogen for underwater welding. I would not recommend its use for anything other than that, hydrogen is very touchy stuff if not treated kindly 

Bb


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## Kaleb (May 26, 2010)

IronHorse  said:
			
		

> A few years ago I got one of those portable Oxy/Ace units for work on my car. They are convenient because you own the tanks. The tanks are only 14" long, but hold a fair amount of gas. Works perfect for silver soldering with a small tip.
> 
> http://www.harborfreight.com/portab...cpc&zmam=13262200&zmas=12&zmac=112&zmap=65818
> 
> IronHorse



That's just what I need, but I'm in Australia.


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## Florian (May 27, 2010)

shred  said:
			
		

> can you post some more details?



I can, but you will have to wait till evening (european time...) 

It is actually just a small tube which adds some additional Air to the gas and the air drawn into by the gas. But i guess it could be optimized to draw in more Air... (when using an air jet and placing it on the outside to carry on some more air. 

cheers Florian


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## bob ward (May 27, 2010)

From here, http://answers.yahoo.com/question/index?qid=20080417075209AAyR9sB, I gleaned that at 100% efficiency a 13.2kw power supply will separate water into H2 and O2 at the rate of 1000kg in 24 hours, or 700gm per minute.

A household 240v 10amp circuit provides 2.4kw, which from the above, will electrolize 130gm per minute. There are losses in the system of course, best practice is around 70% efficient, a home made system could be 50% efficient. Even so, at 50% efficiency you will be electrolizing 65gm of water per minute, which should be enough to do fair size silver solder jobs.

I imagine that the cost to build a safe electrolysis system that can absorb a 2.4kw power supply will outweigh the initial purchase cost of an OA system and a few years bottle rent. I'll leave you to work out the cost of your power consumption v buying OA gas.


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## rickharris (May 27, 2010)

[youtube=425,350]<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/-ceOL83PM24&hl=en_GB&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/-ceOL83PM24&hl=en_GB&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>[/youtube]

There are commercial systems about.


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## Lew Hartswick (May 27, 2010)

It seems about 3/4 of thetime I click on one of these things that are supposed to 
show a vid I get "an error occured try later" . Do others get this or do I have some 
problem?
  ...lew...


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## radfordc (May 27, 2010)

Did you see the ammeter on his machine reading ~20 amps! If this is at 220 v then the power demand is significant (4.4 kw).

Charlie


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## shred (May 27, 2010)

The torch might be ok, but the rest of that video is total BS. Water is not a fuel, it takes far more energy to split it than you ever get back.

I spent several years back in the 80's with a company developing hydrogen vehicles using metal hydrides for the gas storage. Fun stuff.


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## pete (May 29, 2010)

While I've never done it and I'm certainly no expert, The post about generating your own Acetylene is IMO a huge mistake. Every single artical I've ever read about home generation of Acetylene warns about how dangerous this is. 

Pete


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## tel (May 30, 2010)

With a properly designed generator it is no more dangerous than keeping bottled acetylene around the house.


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## Blogwitch (May 30, 2010)

In the UK, it was common to generate your own acetylene up until the early sixties. People couldn't afford the dry batteries that they used in their bicycle lights, so they use 'carbide lights' instead. Many home workshops had acetylene generators as well, so if properly designed and made that could be a very useful addition.

Just two main problems that I can see, getting the carbide in enough quantity to make it viable, plus the very dry storage conditions that it requires, and the main stumbling block, persuading your insurance company that you aren't going to blow up the block. 
As far as I know, there was never any real problems with the generators, but you know what H&S is like nowadays. Pretty soon you will have to have a fire engine on standby if you want to light a ciggy.

Bogs


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## tel (May 30, 2010)

I see your problem Boggy - not too many banana growers in the UK I should imagine


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## ttrikalin (May 30, 2010)

tel, banana growers?
you lost me...

just read the whole thread -- used to ripen bananas --- rang a bell from biochem ...

t


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## pete (May 30, 2010)

Tel,
I'll take you word for it but at least for me I'll buy my Acetylene in a tank.


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## tel (May 30, 2010)

As do I Pete, not from any safety concerns tho' - it's just too much foolin' around and less effective than any dubious saving potential.


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## stefang (May 30, 2010)

Strange luck, yesterday I bought a hydrogen-generator used for soldering, heating, etc..

Its a machine built back 1980 in Germany made by the company Mig-O-Mat:






Very massive unit, weights around 40kg and needs a power supply of 230V by a max. power consumtion of 1,8kVA.

Opened case, there is not much in it:




On the left, there is the transformator, it has a maximum output of around 300Apms at 5,5V, below is the step-switch to select the different windings of the transformator.
On top, in the middle, is the gas reactor, contains caustic potash solution (needs to be refuled with distilled water)...right above of it sits a pressure switch, which limits the gas pressure to 350mbar (ca. 5psi)
Below is the massive selenium rectifier..

Top of the Casing:




The hydrogen/oxygen comes in on the left side and is channeled trough a water separator, then a pressure gauge, and finaly the "booster", which contains methanole and a little amount of borax. The gas bubbles trough this liquid, which helps to make the flame a little bit softer and visible, afterwards, it goes to the torch.

The flame produced by hydrogen and oxygen is incredible hot and focused, with a 1mm long flame, i can burn a hole through 0,5mm steel...its awesome for small silver soldering work...

Its also relative safe, as there is no gas storaged, only the amount between the reactor and the torch...at work I had backfire one of those units, it was relative loud, you are scared to hell, and the hose was shredded a bit..but no "bomb".

Off course, I also have a video of it in action:

[ame]http://www.youtube.com/watch?v=3SqS0L0-W1U[/ame]

Just burning down a 1mm piano wire..

Stefan


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## tel (May 30, 2010)

Nice looking unit Stefan


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## Deanofid (May 30, 2010)

Bogstandard  said:
			
		

> In the UK, it was common to generate your own acetylene up until the early sixties.
> Bogs



In the U.S., also, as John says, and I expect in the rest of the world too, else how would everyone have acetylene before tanks were common? 

By the time I was in the trade, acetylene generators were rare, but I would see one now and then. A shop in my neighborhood still had one, but by then, unused. I've heard them referred to as an 'acetylene bell', and the ones I've seen had that basic shape. A bell reservoir under the generator that had a round tube that held the carbide mineral, with another container for water. The carbide came in tins. 

A pretty neat thing. Fire from rocks and water. Kind of cool, like the other thing we like so much.. Steam from fire and water.

Dean


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## shred (May 30, 2010)

If you know anybody that likes to crawl around in caves, those guys sometimes still use carbide lamps because they'll show a draft when a flashlight won't (and can provide heat, ignition, etc). But, with high-efficiency LEDs and Homeland Security, it's getting more and more difficult to get carbide in bulk..


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## Tin Falcon (May 30, 2010)

Did a quick Google, search calcium carbide is available in the US. Minors grade but the shipping/hazmat fees are high. There is a place that sells 10 lb lots 5 quart sized paint cans for $85($55 of that is shipping and haz mat tax)
acetylene is strange stuff the bottles you buy are filled with vermiculite and acetone. the acetylene is held in solution much like co2 in a bottle of soda water. Tat is why it is important to keep acetylene bottles vertical.The reason for the aceone is acetalene is unstable at above 15 PSI. 
Tin


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