Most fire extinguishers contain dry chemical powder or foam. The most common agent is sodium bicarbonate, or regular baking soda. Other compounds are available, such as potassium carbonate, but not all of them have the same performance. Sodium bicarbonate starts decomposing when temperatures reach 158 degrees Fahrenheit. The carbon dioxide it releases along with the water acts as insulation to contain the fire and prevent it from spreading.
The dry chemical extinguisher, known as a CO2-based extinguisher, is used to put out large-scale fires. This chemical is non-toxic, inexpensive, and easy to clean up. Some models use a cylinder of copper that has an internal CO2-cartridge. An operator turns a wheel valve on the top to puncture the cartridge. The DuGas extinguisher was the first to be used for large-scale fires, but it remained a specialty type until the 1950s.
Fires are usually categorized into three classes. Class A fires are organic solids, while Class B fires are flammable liquids such as petrol. Classes C and D fires are characterized by flammable gases and metals. Classes E and F are electrical equipment and cooking oil and fat. All of them can become Class A if the power supply is interrupted or the fire starts in a confined area.
If you have a Class K fire extinguisher, you should use it in a commercial setting. These units typically contain two-and-a-half gallons of fire-fighting agent. They are compatible with duct and hood fixed extinguishing systems. The fire extinguisher should be aimed at the base of the fire and discharged through the nozzle. Remember to follow the directions on the container label to prevent any re-ignition of the fire.
There are two types of fire extinguishers: water-based and dry chemical systems. Water-based extinguishers are most effective in class A fires because it cools down the burning substance. Water-based extinguishers use air under pressure to direct water onto the fire. Some contain wetting agents to improve their efficacy. For most uses, the water-based extinguisher is the best choice.
The National Fire Protection Association (NFPA) has recently voted to eliminate the 30-day inspection requirement for fire extinguishers. However, it does not mean that you should not check your fire extinguisher. It is important to regularly test it. It is essential to check it at least once a year to make sure it is still working properly and that it is not damaged. A basic inspection of all extinguishers is required every year. You can use a specialized fire safety company to recharge a fire extinguisher.
Dry chemical fire extinguishers are not suitable for use indoors or in strong air currents. Because the chemicals in them dissipate so quickly, they will not completely extinguish a fire. Additionally, dry chemical fire extinguishers reduce oxygen levels in the area of the fire, which is crucial for extinguishment. As such, dry chemical extinguishers should only be used in enclosed areas.