An oxy-acetylene torch is used safely by leak-checking, lighting acetylene first with a striker, setting a neutral flame, then shutting down in order.
Learning how to use an oxy acetylene torch comes down to repeating the same disciplined sequence every time: check the rig for leaks, open cylinders slowly, light acetylene first, tune to a neutral flame, and shut down with the valves in the right order. Skip a step and you’re gambling with a flame hot enough to cut steel. This walkthrough covers the whole cycle, from the inspection before ignition to the last regulator turn at shutdown, including the pressure limits you need to respect.
Before You Light It: Leak Checks and Rig Setup
An oxy-acetylene rig only behaves when every connection is sound, which is why the inspection comes before the flame. Set both cylinders upright and secured so they can’t tip, and open each valve slowly while standing to the side of the regulator. Visually check the regulators, hoses, torch body, and tip for damage, cracked rubber, or loose fittings.
Leak-check every connection with soapy water before igniting anything. Bubbles mean a leak — tighten or replace the part and test again. Two rules matter here more than any other: never use oil or grease on oxygen equipment, and never point the torch at anything you wouldn’t want burned. Wear approved goggles or a face shield, gloves, and flame-resistant clothing, keep combustibles away, and work in a ventilated space. Closed containers such as drums or tanks are never safe to cut or weld.
How Do You Light the Torch Safely?
Lighting the torch follows one fixed order: acetylene first, oxygen second, with a spark striker as the only source of ignition. Matches and cigarette lighters are out — your hand has no business being near the tip when the flame catches. A striker’s spark lights the gas from a safe distance.
- Purge the lines first. Crack the acetylene valve at the torch briefly until you smell gas, then close it.
- Open the acetylene valve at the torch a small amount and light it with the striker. A steady acetylene flame should burn at the tip, smoky but stable.
- Slowly open the oxygen valve and watch the flame sharpen. The goal is a neutral flame: a sharp inner cone with no trailing smoke.
If the flame smokes, reduce the acetylene until it clears; then raise oxygen to define the cone. Set regulators according to the tip manufacturer’s pressure chart — as a starting reference, handouts commonly suggest about 10 psi of acetylene (never above 15 psig in free state) and 25–35 psi of oxygen.
| Flame Type | What It Looks Like | What It’s For |
|---|---|---|
| Neutral | Sharp inner cone, clean blue, no smoke | Welding, brazing, most heating tasks |
| Carburizing (rich) | Feathered, smoky, longer inner cone | Heating; can add carbon if used for welding |
| Oxidizing (lean) | Short, harsh, hissing cone | Cutting; too aggressive for most welding |
Oxy-Acetylene Cutting and Shutdown: The Order That Matters
A clean cut depends on preheat, and a safe shutdown depends on valve order. Support the workpiece with space beneath the cut so molten slag can fall away, then hold the preheat flame near the edge until the metal glows cherry red. Depress the cutting oxygen lever and move steadily along the line — the oxygen jet does the cutting, not the flame itself.
Shut both cylinder valves, then bleed the lines by opening the torch valves until both gauges read zero. Finally, back out the regulator adjusting screws until they turn freely. That zero reading is your cue the hoses are clear.
Never “starve” the tip down to a tiny flame, and know that check valves are not fire stops. UC Santa Barbara’s oxy-acetylene safe work procedure spells out the same inspection, lighting, and shutdown order in full.
If you’re outfitting your own shop instead of borrowing a rig, our tested roundup of acetylene oxygen torches covers the sets worth the money and the features that make setup easier.
FAQs
What PSI Should an Acetylene Regulator Be Set To?
Never set free-state acetylene above 15 psig, the widely cited maximum. Handouts commonly suggest about 10 psi, and typical rigs run 5–7 psi of acetylene with oxygen in the 25–35 psi range. Those are starting points only — the tip manufacturer’s pressure chart is the final authority for your specific torch.
Why Do You Light Acetylene First?
Lighting acetylene first keeps the oxygen side closed until a controlled flame exists at the tip. With oxygen already flowing, the mixture can ignite unpredictably. The striker lights a small, manageable acetylene flame, then oxygen is added gradually to shape it. Shutdown follows the reverse logic: acetylene closes first at the torch.
Can You Use a Lighter to Light an Oxy-Acetylene Torch?
No. Safety handouts are specific: use a spark striker or flint lighter only. Matches and cigarette lighters put your hand near the tip as the flame catches, and a torch that pops or flashes back can burn the fingers holding the ignition source. A striker sparks from a safe distance.
References & Sources
- UC Santa Barbara Environmental Health & Safety. “Safe Work Procedure: Oxy-Acetylene Torch.” Covers inspection, lighting, operation, and shutdown sequence.
- University of Wisconsin–Milwaukee. “Oxy-Acetylene Safety.” Details acetylene pressure limits, flashback response, and required PPE.
- University of Arkansas Division of Agriculture. “Cutting Torch Lesson Plan.” Explains neutral flame adjustment and cutting technique.