torch question

[George]

I get different recommendations from different people on which torch to use to melt silver.  One recommendation was an air/acetylene torch while a welder said that propane is hot enough to melt silver.  And yet another person(Old Home employee) said that map gas was 3 times hotter than propane and would do the job.  The fear I have of air/acetylene is that I heard it can explode and it has to be handled just right.  Whereas the propane torch and Mapp gas torch are easy to use and seem safe.  I appreciate any recommendations.

[Metalman]

Okay – where to start.  
Any and all torch equipment is hazardous.  
In varying sizes and configurations, you have a flammable gas under pressure in a metal tank. With some equipment you also have pressurized air or oxygen in tanks as well. All of these have the potential to explode if handled improperly. Sooooooooo…………..

Read the instructions thoroughly before you use it. If you need additional information – speak with your supplier and or the manufacturer.

In my town, I can buy any of the equipment available online from my welding supplier. I get personalized service and training if I need it. I can also go back with questions when needed.  Another source of help would be any local metalsmiths who teach.

Now that we have the provisos over with – some discussion of torches.
There are 2 basic types:
1] Single gas torches
These would be fueled by propane, butane, methylacetylene propadiene (MAPP®) or acetylene. Most of the torches have open holes in the torch head that feed and mix air into the gas so that it will burn. For small jewelry work, these will work to get started. Frequently these torches do not have a lot of variety in the flame sizes so are not as flexible in use. For casting, the acetylene-based torches are often used although the acetylene gas tends to be a dirty gas, which can be a concern.
As a note, I have heard that the MAPP® gas does burn hotter than the propane.

2] Dual gas torches
These torches use the same gases, with the addition of natural gas, in combination with air or oxygen under pressure. The lower end would be propane or natural gas used with compressed air. The compressed air can come for a compressor or tank – certain amounts of filtering are necessary so that water or oils in the line don’t damage the regulators. Usually these have a large and bushy flames used for annealing large hollowware projects. The next step uses oxygen under pressure. This requires additional regulators and significantly increases the temperature range. You can also get a larger variation of tips and sizes of flame to use for different applications.  

At this point you also get into a choice of tank sizes, regulators, various brands of torches and a real need to be clear about the uses you want the torch for. Small and or disposable is not always the best choice when making these decisions. For initial hobbyist set up, the single gas torches will suffice until your work and interest clarifies and you are ready for further expenses.
Final reminder: Torches are REAL equipment, like tablesaws and bodygrinders. Used properly, you can make and do great things- used improperly, mayhem, maiming and disaster can follow

Great assessment of gases!  

The main qualification of which type of tank and torch to use depends on what kind of work you are doing.  For fabrication techniques in silver, as well as many in gold, an air acetylene torch is necessary.  Oxy/propane, MAPP, and oxy/acetylene are too pinpoint hot as Metalman said.  They are commonly used by commercial jewelers or other people, who do repair work, and are excellent for soldering a tiny replacement prong back onto a ring without removing the diamond.  Melting small amounts of metal or fabricating jewelry from scratch with those types of torches can be like trying to light an entire room with a laser pointer when a plain light bulb would work much better.  It's not how hot the torch gets but the heating situation it creates that's important.

Air/acetylene torches don't put out the sooty mess the way oxy/acetylene torches do.  They are also usually legal and safe to have inside, whereas the propane tanks that are used for grills are not safe to have in an enclosed area even a garage.  (They have warning labels about not keeping them in enclosed areas and will send fire marshals reeling!)  Propane is heavier than air, making it pool and accumulate in the lowest spot of a room, while acetylene is lighter than air and dissipates rapidly.  If propane is necessary, the tiny camping tanks are supposedly ok.  The larger tanks should be kept outside with a line run through the wall for the torch.  

Always keep your tanks chained up securely to a wall or sturdy bench even when they are empty.  The biggest risk is breaking the stem and creating a rocket.  Transport tanks upright, and make sure they can't tip suddenly.  (If you can't transport upright, acetylene tanks should be stood up asap and remain closed for a couple of hours.)

Also, be aware that most tanks have a lead burnout valve on the stem to release the gas and prevent explosion in case of a building fire.  NEVER hold or store your torch near the valve.  

Hope this helps!

[Metalman]

Thanks to Our unknown guest.
Great Information