Rapid Ref : H2142 Mfr Ref : 1401255

Harris Shank 432 MX (Heavy Duty)
1401255 H2142

Name: Harris Shank 432 MX (Heavy Duty)
SKU: H2142
Price: 164.02 GBP

£164.02 EX VAT

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Harris 43-2 Acetylene FAQs

Answers to common questions about the nozzles, mixers, heating heads and cutting attachments used with a modular oxy-acetylene torch.

What pressure should I run acetylene at?

For most welding and cutting jobs the HSE says acetylene pressure should not exceed 0.62 bar (9 psi), unless the equipment has been specifically designed for a higher pressure. Decomposition of acetylene can be triggered more easily and proceed more rapidly if the gas in the hoses is above the pressure recommended by the supplier, so do not simply wind the regulator up to get more heat.

The right working setting for a particular nozzle or mixer is on the manufacturer's chart or data plate. Use only a regulator, hoses and torch parts made for acetylene and marked to the correct standards, and follow your own risk assessment.

Do I need flashback arrestors and non-return valves, and what is the difference?

A non-return (check) valve fitted on the torch stops gas back-feeding into the hoses, but the HSE notes it will not stop a flashback once one has occurred. A flashback arrestor is a different device that stops a flame travelling back towards the cylinder.

HSE guidance is to fit arrestors on the regulators of both the acetylene and oxygen cylinders and, for long hoses, on the torch end as well. Inspect these devices regularly and replace damaged ones. They are not a substitute for safe working practice, so keep to the manufacturer's replacement and testing advice.

How do I purge and light an oxy-acetylene torch safely?

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 of gases in the hose. Work in a well-ventilated area and light the gas with a spark igniter, not a butane lighter or a match held close to your hand.

Use the correct gas pressures and nozzle size for the job. The order in which to close the torch valves at shut-down differs between published instructions, so follow the sequence in your torch manufacturer's manual. Only use the equipment if you have been trained.

How do I choose the right cutting nozzle?

The cutting oxygen bore is chosen by the thickness of material, so larger bores are used on heavier plate. Nozzles are made as one-piece or two-piece designs, and the choice depends on the fuel gas, whether the torch is hand or machine operated, and the maker's design. Standard nozzles have a central oxygen bore surrounded by preheat ports.

Always match the nozzle to the fuel gas and to the torch or cutting attachment it was made for. The maker's chart gives the recommended gas pressures for each size, so check it rather than guessing from a similar tip.

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