How many fire extinguishing systems are there on board? By the way, how it works.

Engine room, commonly known as "engine room", is located at the stern of the ship. During navigation, berthing, manufacturing, maintenance and disassembly, fires will occur in the engine room for various reasons. Engine room is the center of the ship's main mechanical equipment and the "heart" of the ship. It has the characteristics of large enclosed space, complex structure, many combustibles, large fuel reserves, strong thermal conductivity and high fire incidence. Based on the characteristics of ship engine room fire, there are mainly the following aspects: 1, the fire point is hidden, and it is difficult to find the engine room located at the lowest stern of the ship. Generally speaking, most engine rooms are below the waterline. Due to the limitation of ship design, the engine room of large ships generally has no ventilation opening directly to the outside except the fan. The fire caused by the kindling left by workers after work is not easy to be found by people outside the computer room at the beginning, thus delaying the time of fire fighting. 2. After the fire, the engine room spread rapidly. It is the centralized control center of ship power and power. There are many mechanical equipment in the engine room working under high temperature and high pressure. In addition to the main, auxiliary and other mechanical equipment fuel, there are many lubricants. Flammable liquid adheres to the shell of mechanical equipment and the ground, and the oil vapor in the air is very thick. After the fire broke out, the fire would quickly spread to the surrounding upper part along mechanical equipment, cables, oil pipelines and the ground. After a general fire, it may spread to the whole engine room in a short time. If the fire continues to develop, it may spread to adjacent cabins through three forms of heat transfer (heat conduction, radiation and convection), causing adjacent cargo (oil, passenger) cabins and crew living and working places to burn. 3. The engine room is complicated in structure and difficult to extinguish fire. Due to the limitation of the hull, the structure in the engine room is more complicated. The stairs entering the engine room turn many and steep, the iron plate covered with oil slides on the ground, all kinds of equipment are scattered and crowded, and the pipes are criss-crossed. After the fire, smoke gathered and the temperature rose rapidly. There is a lot of smoke in the whole cabin, which is difficult to spread out, making people unable to open their eyes and lose their way quickly. In addition, the temperature in the engine room is high and the radiation heat is strong. It is difficult for fire fighters to go deep into the interior for fire detection, rescue, internal attack and melee fire fighting. 4. There are many explosives, which are easy to explode. There are many explosives such as oil tanks, gas cylinders and high-pressure containers in the engine room. These objects are prone to physical expansion and explosion at high temperature or after burning, which leads to the expansion of fire and even serious consequences of shipwreck and death. 3, gas fire extinguishing system 1)CO2 gas fire extinguishing It uses the inert gas characteristics of CO2 to reduce the oxygen content around the combustion by absorbing heat, so that the combustion can cool down and suffocate, thus achieving the purpose of fire extinguishing. At the same time, because the molecular weight of CO2 is larger than that of air, it is easy to sink, which isolates air from combustion products and stops the combustion reaction. CO2 is cheap and easy to obtain and prepare, but it is easy to suffocate firefighters. 2) Halon Substitute Fire Fighting Due to the entry into force of 1987 Montreal Protocol on Substances that Deplete the Ozone Layer, the traditional halon fire extinguishing agent with superior fire fighting performance has been banned, but it has promoted the birth of a number of halon substitutes such as heptafluoropropane and EBM aerosol. This technology can achieve the purpose of fire extinguishing through strong endothermic decomposition reaction and inhibition of combustion reaction chain, and can be used to extinguish the initial fire of combustible solids, liquids and gases. The disadvantage is that hydrogen fluoride, the product of heptafluoropropane fire extinguishing, will corrode the equipment in the engine room of the ship and do some harm to the human body. Although aerosol is cheap, it does not have good electrical insulation, and the deposition of fire extinguishing agent is harmful to electronic precision instruments. 4. Dry powder (ultra-fine dry powder) fire extinguishing system Dry powder extinguishing agent is a kind of dry and easy-flowing fine powder used for fire extinguishing, which consists of inorganic salts with fire extinguishing effect and a small amount of additives, and is dried, crushed and mixed into fine solid powder. In addition to the special dry powder chemical fire extinguishing agent for fighting metal fires, dry powder fire extinguishing agents are generally divided into BC dry powder fire extinguishing agent and ABC dry powder fire extinguishing agent. Such as sodium bicarbonate dry powder, modified sodium salt dry powder, potassium salt dry powder, ammonium dihydrogen phosphate dry powder, diammonium hydrogen phosphate dry powder, phosphoric acid dry powder and amino dry powder fire extinguishing agent. Dry powder fire extinguishing agent mainly extinguishes the fire through physical and chemical actions when the powder mist sprayed by pressurized gas contacts and mixes with the flame: firstly, the volatile decomposition products of inorganic salts in dry powder chemically inhibit and catalyze the free radicals or active groups generated by fuel during combustion, so that the chain reaction of combustion is interrupted to extinguish the fire; Second, the powder of dry powder falls outside the surface of combustible substances, and chemical reaction occurs under the action of high temperature, forming a glassy coating, thus isolating oxygen and suffocating and extinguishing fire. In addition, there are some oxygen dilution and cooling effects. Ultrafine dry powder is a upstart in the dry powder family. It took six years for the researchers of Wuhan Green Fire Fighting Equipment Co., Ltd. and cost tens of millions to develop successfully. It is the only new fire extinguishing agent that has passed the national type test in China at present, and its fire extinguishing efficiency is 6- 10 times that of ordinary dry powder. It is an environmentally-friendly product with the highest fire extinguishing efficiency, the fastest fire extinguishing speed and the lowest fire extinguishing concentration among the fire extinguishing agents recognized at home and abroad. Ultrafine dry powder is also an aerosol, which is a cold aerosol produced by inert gas driving dry powder particles to be released into space. The ultra-fine dry powder automatic fire extinguishing device takes nitrogen as the power to drive the ultra-fine dry powder extinguishing agent in the fire extinguishing device to extinguish the fire. It is started silently, similar to gas fire extinguishing, and the nitrogen pressure is 1.2MPA, which is safe and reliable, without any damage to the protected object. In addition to environmental protection, the filled superfine dry powder fire extinguishing agent also has the characteristics of the highest fire extinguishing efficiency, the fastest fire extinguishing speed, the lowest fire extinguishing concentration and the widest fire extinguishing range, which fully meets the highest requirements of today's fire protection. Hanging, cabinet and wall-mounted fire alarm systems can be connected to form an automatic fire extinguishing system. Its fire extinguishing system without pipe network (hanging type, cabinet type and wall-mounted type) is simple to install and low in cost, and can extinguish fires in large spaces; There are three startup modes for total flooding fire extinguishing or local protection fire extinguishing, namely, electric control startup, constant temperature startup and hot startup, which can be flexibly used according to the site environment, can be used to extinguish Class A, B, C and live equipment fires, and has a wide application range, especially suitable for ship engine room fire extinguishing. No pipe network is represented by hanging type, which is convenient to install, without drilling holes through walls, and multiple devices can be started simultaneously by electric control and hot start; Cabinet fire extinguishing device has high degree of automation, safety and reliability, and great fire extinguishing power. Electronic control start: it can interface with the alarm controller commonly used in the market, and it can be set that the alarm host will alarm only when it receives the independent signal of the detector; When the upper computer receives two independent signals, it gives an alarm and delays for 30 seconds, and then sends a 24-volt power supply to the fire extinguishing device to start the fire extinguishing device, and can realize various functions such as starting in different zones, feeding back and releasing signals, and linking with other devices. Temperature control start-up: the suspended fire extinguishing device is equipped with a constant temperature nozzle, the temperature sensing element can be selected between 57 degrees and 14 1 degree, and the ambient temperature can be selected between -40 degrees and +55 degrees. When there are no more than 8 in a protected area, you can choose to start at constant temperature. Hot start: when there are more than eight fire extinguishing devices in a protected area, hot start can also be used; In other words, multiple fire extinguishing devices in the protected area are connected together by hot wires, which can realize simultaneous start-up.