Harris 19-6 Acetylene FAQs
Answers to common questions about the mixers, neck tubes, cutting attachments and nozzles used on a hand-held oxy-acetylene torch.
What parts make up an oxy-acetylene hand torch, and does each part have to suit acetylene?
A hand torch is built from a handle or shank with the gas valves, a mixer where the oxygen and fuel gas meet, a neck or flame tube, and a nozzle or tip at the end. Cutting attachments and heating nozzles fit onto the same shank.
Mixers, nozzles and attachments are usually made for a particular fuel gas, because the internal passages are sized for that gas. Check the marking and the maker's manual before fitting anything, and do not assume a part sold for another fuel will work on acetylene.
What is the correct way to purge, light and shut down an oxy-acetylene torch?
Before lighting, purge the hoses one at a time by opening the gas supply to each hose for a few seconds, then close the torch valve. This flushes out any flammable mixture. Work in a well-ventilated area, light the gas with a spark ignitor, and use the correct pressures and nozzle size for the job.
When you have finished, turn off all valves at the cylinders and torch, then vent the excess gas from the hoses. Do not use the equipment unless you have been trained, and follow the maker's instructions and your risk assessment.
What is the difference between a flashback arrestor and a non-return valve?
A flashback arrestor is designed to stop a flame, using an element such as fine mesh or metal foam that cools it out. Some also have a cut-off valve that operates on pressure or temperature. A non-return valve only controls the direction of flow, so oxygen cannot pass into the fuel line or the reverse. It has no flame-stopping ability.
HSE guidance is to fit flashback arrestors, or an equivalent device, at the regulators on both the oxygen and acetylene cylinders, and non-return valves on the torch. Fitting them is not a substitute for safe working practice.
How should I look after nozzles and what happens if they are damaged or blocked?
Inspect nozzles regularly and make sure they are not blocked by dirt or spatter. Poorly maintained nozzles cause turbulent gas flow, which increases the risk of flashback. Replace any nozzle that is damaged.
Do not hold the nozzle too close to the workpiece, as it can overheat and cause a flashback or backfire. Clean tips with the correct cleaning tools and take care not to enlarge or scratch the bore. If the nozzle seat or mixer is damaged and the connection leaks, replace the part or have it repaired rather than overtightening it.