Foam extinguisher is suitable for fighting general Class B fires, such as oil and grease fires, but it can't fight live equipment.

Dry powder fire extinguisher is suitable for extinguishing the initial fire of oil, combustible gas and electrical equipment.

When in use, first open the safety pin, hold the spray pipe with one hand, aim at the fire source, and pull the pull ring with the other hand to extinguish the fire source.

Liquid carbon dioxide fire extinguisher has the characteristics of no moisture, no electricity, no damage to substances, no stains and so on, which is very suitable for extinguishing fires in electrical appliances, precision instruments, libraries, archives and other places. But it can't be used to put out fires of metals such as potassium, sodium and magnesium, because these metals will react with carbon dioxide and increase the fire.

When using a carbon dioxide fire extinguisher, you must put your hand on the wooden handle behind the spray pipe before starting it.

Electrical equipment fires can be put out with sodium ammonium phosphate dry powder and carbon tetrachloride, and with carbon dioxide fire extinguishers, but carbon dioxide fire extinguishers with metal horn nozzles are not allowed. Foam extinguisher cannot be used to put out fires of electrical equipment.

(1) chemistry laboratory: foam extinguisher, dry powder fire extinguishers, carbon dioxide fire extinguishers and carbon tetrachloride fire extinguishers are all required, because the fire factors in the chemistry laboratory are complicated, and some common substances catch fire, such as paper and flammable organic substances. At this time, foam extinguisher or dry powder fire extinguisher can be used to put out the fire, and sometimes the electrical equipment is on fire (there are quite a few types of electrical equipment in the chemistry laboratory, such as vacuum pump, centrifuge, electric furnace, acid meter, etc.). At this time, only carbon dioxide or carbon tetrachloride fire extinguishers can be used, but foam extinguisher and foam extinguisher are prone to electric shock. Carbon dioxide and carbon tetrachloride fire extinguishers produce gas, which is isolated from the air and can put out electrical fires. If it is a very sophisticated or expensive instrument, you should use a carbon dioxide fire extinguisher, because it will not leave traces and will not damage the equipment. Carbon tetrachloride fire extinguisher can emit heavy carbon tetrachloride inert steam, which can isolate the air and can be used to extinguish electrical fires, but it is not suitable for extinguishing fires at high temperature, because carbon tetrachloride will react with oxygen in the air at high temperature to generate highly toxic phosgene (COCl2). Of course, it should be noted that if the fire is caused by active metals such as sodium and magnesium, it can only be put out with sand, because carbon dioxide can also support the combustion of these metals like oxygen, so it will not put out the fire, but will strengthen the fire. Foam, dry powder and carbon dioxide fire extinguishers all contain carbon dioxide; Carbon tetrachloride fire extinguishers are also unsafe, because these metals burn at high temperatures and carbon tetrachloride will produce phosgene.

(2) Physics laboratory: Generally, carbon dioxide fire extinguishers and carbon tetrachloride fire extinguishers are more suitable, because in physics laboratory, the trigger factor of fire is mostly electrical short circuit, so these two kinds of fire extinguishers are suitable for extinguishing electrical fires, and they should be pressed in physics laboratory. Moreover, the instruments in the physics laboratory are more precise or expensive, so it is more appropriate to use a clean fire extinguisher without leaving traces, so the carbon dioxide fire extinguisher is the first choice.

(3) Computer room: mainly carbon dioxide fire extinguishers, carbon tetrachloride fire extinguishers can also be considered, but carbon dioxide fire extinguishers are still the first choice, because the factors of computer room fires are mainly electrical related factors such as short circuit of electrical appliances, and computers are expensive electrical appliances, so using carbon dioxide fire extinguishers can not only effectively control the fire, but also prevent computers of valuables from being damaged, and also prevent electric shock (if water or foam extinguisher is used, it will get an electric shock). Carbon tetrachloride is a toxic organic substance, so it is not recommended to use it, so personally, carbon dioxide fire extinguishers are better than carbon tetrachloride fire extinguishers.