Class D, Metal Fire Extinguishers
If you work with flammable metals, you’ll need specialist metal fire extinguishers.
flammable metals – aluminium, lithium, titanium, sodium, magnesium, etc.
What do they look like?
Metal fire extinguishers are classed as dry powder fire extinguishers
, so they will have the same blue label that ABC powder extinguishers use.
Types of metal fire extinguisher
There are several types of metal fire extinguisher, so it’s important that you use the right one. The most common ones are L2 and M28 dry powder fire extinguishers.
M28 fire extinguishers:
For class D fires, especially alkali metals (e.g. sodium, potassium, magnesium and aluminium)
L2 fire extinguishers:
For all class D fires, including lithium ones
About M28 (sodium chloride) fire extinguishers
M28 fire extinguishers contain sodium chloride – which is basically salt – which has been treated with flow and moisture repellent additives. The sodium chloride will form a crust over the fire to smother it.
Generally, you’ll need 3 – 5kg of powder per kilo of metal that is burning.
To prevent molten metal from spreading, M28 fire extinguishers have a long hose and lance, along with a slow release applicator. This makes them ideal if your metal is in powder or swarf (waste) form,
This type of extinguisher is especially strong at fighting fires involving alkali metals.
About Lithium fire extinguishers
Lithium fire extinguishers are commonly sold in the form of L2 fire extinguishers. They normally contain copper powder or graphite powder.
Copper powder coats any static or moving lithium. It will also stick to a vertical surface.
Graphite powder works in much the same way, with an added benefit. Since it draws heat away from the fire, it can also be used to fight fires that burn at incredibly high temperatures, such as zirconium or titanium fires. However, unlike copper powder, granite powder will not stick to a vertical surface.