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

[Kaleb]

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.

 

[tel]

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.

 

[Florian]

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

 

[shred]

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?

 

[IronHorse]

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

 

[bucketboy]

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

 

[Kaleb]

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.

 

[Florian]

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

 

[bob ward]

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.

 

[rickharris]

[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.

 

[Lew Hartswick]

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...

 

[radfordc]

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

 

[shred]

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.

 

[pete]

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

 

[tel]

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

 

[Blogwitch]

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

 

[tel]

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

 

[ttrikalin]

tel, banana growers?
you lost me...

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

t

 

[pete]

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

 

[tel]

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.