Fire extinguishers are portable devices that release fire-fighting agents through a nozzle, using internal pressure. They are known for their simple structure, lightweight design, ease of use, and wide applicability, making them one of the most effective tools for combating fires. Students often encounter fire extinguishers in various locations on campus such as dormitory corridors, laboratories, classrooms, and auditoriums. The placement of these devices is determined based on the hazard level of the building, typically mounted in fire extinguisher boxes or hung 1.5 meters above the ground. In case of a fire, it's essential to remain calm and assess the situation before using the extinguisher effectively.
**First, Types and Selection of Common Fire Extinguishers**
1. **Types of Fire Extinguishers**
Fire extinguishers come in various types and can be classified in three main ways: by mobility (portable or cart-mounted), by the driving force of the agent (gas cylinder, pressure-stored, or chemical reaction type), and by the type of extinguishing agent used (foam, dry powder, halogenated hydrocarbons, carbon dioxide, acid-alkali, water, etc.).
2. **Selecting the Right Fire Extinguisher**
Choosing the correct fire extinguisher is crucial when dealing with an initial fire. The selection should depend on the type of material burning.
- **Class A Fires (Solid Materials):** Water, foam, ammonium phosphate dry powder, and halogenated extinguishers are suitable.
- **Class B Fires (Flammable Liquids and Meltable Solids):** Foam, dry powder, halogenated, and carbon dioxide extinguishers can be used.
- **Class C Fires (Gas):** Dry powder, halogenated, and carbon dioxide extinguishers are appropriate choices.
- **Class D Fires (Metal):** Graphite powder extinguishers are recommended, along with dry sand or cast iron dust.
- **Class E Fires (Electrical Equipment):** Dry powder, halogenated, and carbon dioxide extinguishers are suitable for electrical fires.
- **Special Situations (Archives, Books, Artworks):** Halon or special extinguishers must be used to avoid damage to valuable items.
**Second, Using Fire Extinguishers and Fire Hydrants**
When a fire first starts, it is the best time to use a fire extinguisher. Correct and proper usage is critical. Here’s how to use some common types:
1. **Using a Carbon Dioxide Fire Extinguisher**
These are ideal for flammable liquids, gases, and electrical equipment. Stand about 5 meters away from the fire, pull the safety pin, and hold the handle and horn. Avoid touching the horn directly to prevent frostbite. Spray from the base of the fire, and if indoors, exit quickly after use to avoid suffocation.
2. **Using a Portable 1211 Fire Extinguisher**
Suitable for early fires in sensitive areas like archives and electronics. Hold the nozzle and spray at the base of the flame. Do not use it upside down or horizontally, and avoid inhaling the fumes.
3. **Using a Cart-Mounted 1211 Fire Extinguisher**
Requires two people. One person controls the nozzle while the other opens the valve. It works similarly to the portable version but covers larger areas.
4. **Using a Dry Powder Fire Extinguisher**
Effective for flammable liquids, gases, and electrical fires. Hold the nozzle and press the handle. Aim at the base of the fire, and continue spraying until fully extinguished. For liquid fires, avoid spraying directly on the surface to prevent splashing.
Always remember to check the fire extinguisher regularly and ensure you know how to use it properly. Stay alert and act quickly in emergencies.
China Labor Insurance Network
A laboratory overhead stirrer is a device used in chemistry and biology laboratories to mix and stir liquids. It consists of a motor that drives a rotating shaft with a stirring blade or paddle attached to the end. The motor is mounted on a stand that is suspended from the ceiling, hence the name "overhead stirrer". The stirring speed can be adjusted by the user, and the device can be programmed to run for a set period of time. Overhead stirrers are commonly used in chemical synthesis, cell culture, and microbiology applications. They are particularly useful for mixing viscous liquids, suspensions, and emulsions, and for maintaining a consistent mixing speed over long periods of time.
Overhead Stirrer,Laboratory Electric Stirrer,Laboratory Digital Agitator,Laboratory Overhead Stirrer
Lachoi Scientific Instrument (Shaoxing) Co., Ltd. , https://www.lachoinst.com