Fire is one of the most common hazards in daily life, making fire extinguishers essential safety equipment for homes, workplaces, and public spaces. The Sodium Bicarbonate Extinguisher uses sodium bicarbonate as its primary extinguishing agent and is widely used for combating small fires, particularly those involving grease and electrical fires.
Principle of Operation
Sodium bicarbonate (NaHCO₃) is an alkaline compound that decomposes under high temperatures, producing carbon dioxide (CO₂), water vapor, and sodium carbonate. Its fire-extinguishing process includes the following steps:
Cooling Effect:
Released CO₂ rapidly diffuses and absorbs heat from the fire source, reducing the temperature.
Smothering Effect:
The inert CO₂ gas forms a layer over the burning area, cutting off the oxygen supply and disrupting one of the three elements of combustion.
Isolation Effect:
Residual sodium carbonate covers the surface of the burning material, isolating it from air and preventing re-ignition.
Applications
The sodium bicarbonate extinguisher is mainly effective for the following types of fires:
Class B Fires (Flammable Liquids): Fires involving substances like gasoline, diesel, and paint.
Class C Fires (Flammable Gases): Fires caused by natural gas, propane, or hydrogen.
Electrical Fires: Ideal for fires involving electrical equipment due to its non-conductive dry chemical agent.
Note: This extinguisher is not suitable for Class A fires (ordinary combustibles like wood or paper) due to its limited cooling and penetration effects.
Sodium Bicarbonate Quality Requirements for Fire Extinguishers
The quality of sodium bicarbonate directly impacts the effectiveness, safety, and performance of the extinguisher. Below are the key requirements:
1. Purity
High Purity:
Sodium bicarbonate for extinguishers must have a purity level of over 99% to ensure efficient CO₂ release and prevent adverse effects from impurities like corrosion or unwanted chemical reactions.
Low Impurity Content:
Excessive amounts of chlorides, sulfides, or other contaminants that may impair extinguishing effectiveness or equipment durability should be avoided.
2. Particle Size
Uniform Distribution:
Particles should be evenly sized, typically within the range of 20–75 microns. Smaller particles enhance coverage, while overly large ones may cause uneven discharge.
Anti-Caking Property:
The particle design must prevent clumping due to moisture absorption, ensuring smooth powder discharge.
3. Moisture Absorption and Resistance
Low Hygroscopicity:
Sodium bicarbonate is naturally hygroscopic. Special treatment, such as hydrophobic surface coatings, minimizes clumping in humid environments.
Moisture Resistance Modification:
Manufacturers often add agents like silicone oil to enhance water resistance further.
4. Thermal Decomposition Performance
Appropriate Decomposition Temperature:
Sodium bicarbonate should decompose efficiently at 150–200°C to release CO₂ and water vapor quickly in high-temperature fire conditions.
High Decomposition Efficiency:
The process should minimize excess solid residue to maintain effective fire coverage.
5. Non-Toxicity and Environmental Safety
Low Toxicity or Non-Toxicity:
The compound should be safe for humans and the environment, with residue causing no pollution or secondary hazards.
Compliance with Environmental Regulations:
Production and usage must adhere to relevant environmental standards to minimize potential impacts on air and soil.
6. Additional Properties
Anti-Static Performance:
Powdered sodium bicarbonate may generate static electricity during rapid discharge. Anti-static properties reduce the risk of secondary explosions.
Flowability:
The powder must exhibit excellent flowability for uniform distribution and smooth discharge from the extinguisher.
