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.
How does a cutting attachment work, and what size nozzle do I need?
A cutting attachment has two oxygen supplies to the nozzle. One oxygen stream is mixed with acetylene to make the preheat flames, and a separate stream, controlled by a lever, is the cutting oxygen that burns through the heated steel.
The cutting nozzle is chosen by the thickness of the material, as the diameter of the cutting oxygen hole is matched to the job. Too little cutting oxygen gives poor slag removal, and too much gives a rough finish. Keep the nozzle at the distance the maker recommends from the plate, as too close or too far disturbs the cut.
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.
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.