Did you know? some metals heat up very quickly under a flame and can become a greater burn hazard. Others are brittle and can not take impacts and some can give off toxic fumes. These are things your should know for your own safety!

The facts about metal components

We have provided this useful information so you can select safer, impact resistant, and longer life fire twirling equipment. Please feel free to print for your own records.

Zinc.

Zinc coatings on mild steel extend the corrosion life by 20 times. However coating melting point is low at between 400-450degC and when burnt can generate Zinc Oxide fume which is toxic and an irritant, which may lead to zinc or metal fume fever. However "Metal fume fever" is a short lasting, self limiting condition with symptoms similar to influenza, and unlikely with normal use. The fuel will be giving off toxic fumes anyway. Zinc has a higher thermal conductivity than plain steel, so watch out for burns from smaller zinc coated items. These items are generally very cheap. NB: not used in our products.

Cast iron or iron ore.

Some swivel clips and connectors. Is very cheap, heavy, hard and very brittle so can break on impact. Do not use.

Copper.

Copper has a very high thermal conductivity and will heat up very fast under a flame. Watch out for burns!

Aluminium aka Aluminum.

Common used Alloy 6063. Melting point is 660degC. When melting will create a respiratory irritant. Softer metal . Aluminium has a higher thermal conductivity (4 x )than plain steel. Never use aluminium ball chain as it heats up quickly because of it small mass and breaks very easily. However it is suitable for tube core poi heads and as tube for a twirling staff if the wall thickness is sufficient.

Brass.

Safer than Zinc with a higher melting point of 940degC (twice that of Zinc) but with similar thermal conductivity to Zinc. When burnt under extreme flame can generate Zinc Oxide fume which is toxic and an irritant, which may lead to zinc or metal fume fever. However "Metal fume fever" is a short lasting, self limiting condition with symptoms similar to influenza, and unlikely with normal use. The fuel will be giving off toxic fumes anyway.

Mild steel.

The melting point of mild steel is 1515 ° C. This will rust with time unless plated or coated. Coatings will wear off with time. Hardened carbon steel is much harder than mild steel, but still brittle and with internal stresses. Case hardened carbon steel provides a tough interior while providing a hard, but more brittle exterior. With many months of heating and cooling we have seen high impact components snap so be careful where this metal is used.

Dangerous use of Mild steel key/split rings: Continuous heating and reheating of these rings with any centrifugal forces causes the ring to open up. Standard cheap low carbon key rings will weaken at 260 Deg C. within 2 minutes!

Even small stainless steel splitrings will open. Remove risk, increase product safety and product life by using stainless steel quicklinks. See Stainless steel quicklinks and parts

Nickel Plated Steel.
Nickel is tougher than iron and is harder and more durable. Nickel provides greater abrasion and corrosion resistance. Overheating will cause nickel plating to come off mild steel. However it will not melt under 1450degC. when it would then become an irritant of the eyes, nose and throat.

Type 304 Stainless steel.

Type 304 stainless steel contains iron, nickel and chromium. It is this addition of chromium and nickel that gives the steel its unique stainless,abrasion and corrosion resisting properties. Although not as hard as high carbon steel it provides high strength without brittleness. With a melting point of 1420degC, after which it will then irritate the eyes nose and throat. Stainless steel has a much lower (1/3) thermal conductivity than plain steel and will heat up under a flame much more slowly so the effect of any burns will be less. Benefits of stainless steel include: Corrosion resistance, Fire and heat resistance (retains strength), attractive appearance, strength to weight advantage, high impact resistance, and very long life.

With so many benefits stainless steel is the preferred alloy for use on fire twirling equipment.

 

See also  Your guide to ball chain cords and components , Stainless steel equipment and parts, Fire poi

References: HSE UK, Nickel institute, Fire Science and Technology, The stainless steel information center, American Iron and Steel institute, Fire research information Services