Laboratory Safety Knowledge

Laboratory Safety Knowledge

1. What is burning? What are the conditions for burning, fire prevention and fire extinguishing? Simply put, combustion is a violent chemical reaction that produces both light and heat. The three conditions for the combustion process are: 1) the presence of combustible substances; 2) the temperature above the ignition point is reached; 3) the presence of a sufficient amount of oxygen. The corresponding conditions for fire prevention and fire extinguishing are: 1) Remove or isolate the source of the combustible material; 2) Cool the burning material to make its temperature drop below the ignition point of the combustible material, and isolate all heat sources; 3) Isolate the source of air.

2. What are the reasons for the fire in the laboratory? 1) Direct action of an open flame; 2) Contact with hot objects; 3) Sparks caused by electrical equipment and static electricity; 4) Effects of heat released by chemical reactions; 5) Overheating of objects or sparks due to mechanical reasons; 6) Light energy Impact. For example, a round-bottomed flask filled with water, placed on a wooden workbench or with combustible materials such as paper nearby, will concentrate light and cause burning when it is directly irradiated by sunlight.

3. Why are foam fire extinguishers not suitable for extinguishing alcohol fires? Because the function of the foam fire extinguisher is to use the sprayed foam to cover the burning material, so that it is isolated from the air flow and stops burning. Alcohol itself is a demulsifier, and the foam falls on the overflowing alcohol, including the burning alcohol, the foam cannot be formed, and even if it is formed, it will be destroyed. to extinguishing the fire.

4. Why is it better to use a carbon dioxide fire extinguisher than a foam fire extinguisher for a fire in the laboratory? Because the solid carbon dioxide ejected from the carbon dioxide fire extinguisher is completely vaporized in a very short time, and no residue is left, it will neither cause water damage nor damage any instruments. For instruments with current passing through, it can also be used without Conducts electricity, ensures personal safety, and is the most effective for extinguishing minor fires. The foam fire extinguisher, due to the high injection pressure, is easy to damage the glass equipment, and the foam pollutes the fire site and soils the equipment. At the same time, it is a good conductor and cannot be used for fire caused by electricity. Therefore, when putting out fires in the laboratory, it is better to use carbon dioxide extinguishers than foam extinguishers.