Fire extinguishers are portable devices that discharge fire-fighting agents through a nozzle, using internal pressure. They are known for their simple structure, lightweight design, ease of operation, and wide range of applications. As one of the most effective tools for fighting fires, they are commonly found in various locations on campus such as dormitory corridors, laboratories, classrooms, and auditoriums. The placement of fire extinguishers is determined based on the hazard level of the building. Typically, they are stored in fire extinguisher cabinets or mounted on walls at a height of about 1.5 meters from the ground. In case of a fire, it is important to remain calm, assess the situation, and use the fire extinguisher effectively.
**First, Types and Selection of Common Fire Extinguishers**
1. **Types of Fire Extinguishers**
There are several types of fire extinguishers, which can be classified in three main ways:
- By mobility: Portable and wheeled (cart-type) extinguishers.
- By power source: Gas cylinder type, pressure storage type, and chemical reaction type.
- By the agent used: Foam, dry powder, halogenated hydrocarbons, carbon dioxide, acid and alkali, and water-based extinguishers.
2. **Selecting the Right Fire Extinguisher**
When dealing with an initial fire, it's essential to choose the appropriate extinguisher based on the type of material burning.
- For solid material fires (Class A): Water, foam, ammonium phosphate dry powder, and halogenated extinguishers are suitable.
- For liquid and melting solid fires (Class B): Foam, dry powder, halogenated, and carbon dioxide extinguishers can be used. Note that chemical foam is only suitable for non-polar solvents.
- For gas fires (Class C): Dry powder, halogenated, and carbon dioxide extinguishers are effective.
- For metal fires (Class D): Graphite powder or dry sand may be used. Specialized dry powder extinguishers are not typically available on campuses.
- For electrical fires (Class E): Dry powder, halogenated, and carbon dioxide extinguishers are recommended. These include fires involving appliances, electronics, and energized wiring.
- For fires involving archives, books, or valuable items: Halogenated or special extinguishers should be used to avoid damaging irreplaceable materials.
**Second, How to Use Fire Extinguishers and Fire Hydrants**
When a fire starts, it is the best time to act quickly and use a fire extinguisher properly. Here are some common methods for using different types:
1. **Using a Carbon Dioxide Fire Extinguisher**
This type is ideal for flammable liquids, gases, and small fires in sensitive areas like instruments, archives, and low-voltage equipment. Stand about 5 meters away from the fire, pull the safety pin, and hold the horn with one hand while pressing the valve with the other. Do not touch the horn directly to avoid frostbite. When spraying, aim from near to far and avoid directly hitting the surface of flammable liquids to prevent splashing.
2. **Using a Portable 1211 Fire Extinguisher**
This is suitable for fires in archives, electronics, and cultural relics but not for metal fires. Hold the extinguisher close to the fire, remove the safety pin, and spray from the base of the flames. Avoid using it upside down or horizontally. If used indoors, ensure proper ventilation to avoid inhalation risks.
3. **Using a Cart-Type 1211 Fire Extinguisher**
Similar to the portable version, two people usually operate this type. One person directs the hose while the other opens the valve.
4. **Using a Dry Powder Fire Extinguisher**
These are effective against flammable liquids, gases, and electrical fires. Carry the extinguisher to the fire site, remove the safety pin, and press the handle to release the powder. Aim at the base of the fire and sweep side to side until fully extinguished.
In all cases, always stay calm, assess the situation, and act quickly. Fire extinguishers are powerful tools, but their effectiveness depends on correct usage and understanding of the fire type.
China Labor Insurance Network
Analytical Balance
An analytical balance is a highly precise laboratory instrument used to measure the mass or weight of samples with high accuracy and precision. It is commonly used in analytical chemistry, pharmaceuticals, and other scientific fields where precise measurements are required. Analytical balances typically have a readability of 0.1 milligrams (0.0001 grams) or less and are designed to minimize external factors that may affect the measurement, such as air currents and temperature fluctuations. They often use a draft shield to protect the sample from external influences and have a built-in calibration system to ensure accurate readings. Analytical balances can be operated manually or electronically, and some models are equipped with advanced features such as automatic calibration, data storage, and connectivity to a computer or other devices.
Analytical Balance,Analytical Scales,Laboratory Analytical Scale,Laboratory Analytical Balance
Lachoi Scientific Instrument (Shaoxing) Co., Ltd. , https://www.lachoinst.com