Question 1

How do I safely set the pressure on an air/acetylene torch for jewelry work?

Accepted Answer

I use the regulator to keep the hose pressure under 15 PSI—going above that is dangerous because acetylene can combust on its own at higher pressures. In practice, I usually set it around 10 PSI. If I overshoot, I bleed gas out at the torch valve to actually bring the gauge down, then dial it back in.

Question 2

Why is it dangerous to run acetylene above 15 PSI?

Accepted Answer

Acetylene is very flammable, and above about 15 PSI it can combust without an ignition source, which means explosion risk. That’s why I point out the red zone on the gauge and emphasize keeping the needle out of it. The regulator is there specifically to keep the hose pressure in the safe range.

Question 3

When should I stop using an acetylene tank and request a refill?

Accepted Answer

When the tank pressure gets down to around 25 PSI (below that 50 mark on our gauge), I stop and tell a facilitator or staff member. The acetylene is dissolved in acetone in the tank, and when it gets low, acetone can start coming into the hoses. That can damage hoses and won’t burn well (and it won’t smell good either).

Question 4

How do I light a Smith Handi-Heet air/acetylene torch with a sparker?

Accepted Answer

I crack the torch valve just a teensy bit—about a sixteenth of a turn—so only a little gas is flowing. Then I strike the sparker in front of the tip to ignite it, and adjust the valve to get the flame size I want. To make the sparker work well, I squeeze the handle and pull down so the flint drags and throws real sparks.

Question 5

What tip size should I use for jewelry soldering vs melting metal?

Accepted Answer

I pick the tip based on the flame size I need: smaller tips give a smaller, more pinpoint flame, and larger tips give a bigger flame for melting larger amounts of metal. In the video I show a size 0 tip, and mention there’s an even smaller 00 and larger tips up to size 2. The tip size is stamped right on the side, so I always check the marking.

Question 6

Do I need special shaded glasses for an air/acetylene torch?

Accepted Answer

I still wear eye protection like I do anywhere in the metal shop, but for this air/acetylene setup I don’t need shaded lenses the way you would with oxy/acetylene. It’s not that blindingly bright. If you want extra protection, you can always choose to wear shaded glasses anyway.

Question 7

What’s the correct shutdown procedure for an air/acetylene jewelry torch?

Accepted Answer

First I close the tank valve fully—clockwise until it stops—because it’s expensive, explosive gas and I don’t want leaks. Then I bleed the lines by opening the torch valve until the regulator gauge drops to zero, and close the torch valve again. Last, I back the regulator screw out until it’s loose (so I’m not compressing the spring), then remove the tip, coil the hose, and put everything back.

Question 8

Why do I need ventilation when using an air/acetylene torch at a jewelry bench?

Accepted Answer

Even in normal use, the torch can create gases you don’t want to be breathing, so I turn on the vacuum and position the vacuum arm right where I’m working. I also avoid heating anything with coatings because those can burn off and make nasty fumes. Good capture at the bench makes the whole process safer and more comfortable.

Using the Smith Handi-Heet Air/Acetylene Torch for Jewelry

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