Diatomaceous Earth (DE) is a fine, naturally occurring powder made from the fossilized remains of diatoms, which are ancient, hard-shelled microalgae. These remains form a soft, siliceous sedimentary rock that is then crushed into a lightweight powder. DE is widely used across many industries, including as a filtration aid, a mild abrasive, and a mechanical insecticide for pest control. This article examines the physical and chemical properties of DE to address its fire safety profile and determine whether it is flammable.
Chemical Composition and Non-Flammability
Diatomaceous earth is definitively classified as a non-combustible material. Flammability requires a substance to undergo a rapid chemical reaction with an oxidant, usually oxygen, to burn or ignite. DE cannot participate in this reaction because its primary component is already fully oxidized.
The material is composed of 80% to 90% amorphous silicon dioxide, also called silica. Silicon dioxide is a mineral compound where silicon is bonded to two oxygen atoms. Since this material is essentially a mineral oxide, it is chemically inert and lacks the components necessary to ignite or sustain a flame. Therefore, diatomaceous earth will not burn, explode, or contribute fuel to a fire.
Thermal Stability and Refractory Properties
Diatomaceous earth’s reaction to extreme heat is characterized by its high thermal stability. The high silica content gives it excellent heat resistance, classifying it as a refractory material. A refractory material retains its physical and chemical properties at temperatures above 1,000°C (1,832°F).
DE possesses a high melting point, typically ranging from 1,230°C to 1,710°C. This stability makes it an effective thermal insulator because its porous structure is highly efficient at trapping air and resisting heat transfer. This property is leveraged in industrial applications, such as the construction of fireproof cabinets to enhance heat absorption and insulation.
Fire Safety and Storage Implications
The non-combustible nature of diatomaceous earth simplifies its storage and handling concerning fire safety. It is safe to store near heat sources because it will not catch fire, break down, or act as an accelerant in the event of a surrounding fire.
Its stability and inert composition allow it to be used as an absorbent or filler in certain fire safety applications. Its high porosity makes it useful for cleaning up spilled liquids, including flammable materials. While DE is fireproof, it is not a primary fire extinguishing agent. The main storage concern for the powder is protecting it from moisture, as water can cause clumping and reduce its efficacy.