Aqueous Vermiculite Dispersion (AVD) fire extinguishing agent is a new, revolutionary technology that has key benefits over existing solutions utilising fixed and portable delivery techniques. AVD is an aqueous dispersion of chemically exfoliated Vermiculite is applied in the form as a mist. Vermiculite is the name given to a group of hydrated laminar minerals which are Aluminium-Iron-Magnesium Silicates. Raw vermiculite consists of thin, flat flakes containing microscopic layers of water.
When Vermiculite is exfoliated either thermally or chemically, the microscopic layers of water are removed and this either causes expansion (thermally exfoliated) or creates microscopic, individual platelets that are freely suspended in water (chemically exfoliated).
Due to the reactivity between a flammable metal fire and water, AVD is applied in the form of a "mist". The Vermiculite particles within the mist are deposited on the surface of the burning fuel to create a film over the top of the fire. This film instantly dries and because the high aspect ratio platelet particles overlap and bind together, they produce a non-flammable oxygen barrier between the fire and the atmosphere.
This process offers cooling to the surface of the fire and as the AVD platelets begin to build up layer upon layer of vermiculite particles on the top of the fuel source, the fire is gradually cooled and brought under control. Unlike other Class D Extinguishing Agents where the fire has to be left for long periods of time before the fire is truly under control and completely burnt out, AVD offers rapid control of the fire.
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When Lithium-ion batteries are exposed to heat, physical/impact damage or over charging they go into thermal runaway.
The cells are sufficiently swollen releasing hot flammable gases (hydrocarbons) which can ignite.
The Hydrocarbons burn vigorously at high temperature and rapidly heat surrounding cells and materials resulting in a significant fire.
AVD is applied as a fine mist, which instantly cools the batteries and extinguishes the flames.
The AVD encapsulates the fuel source and insulates the cells preventing further thermal runaway; bringing the fire under control.