1. burning speed
Oil fires, in the early stages of combustion speed is slow, with the depth of combustion increases, the burning speed is also gradually accelerated until it reaches its maximum value. Thereafter, the burning speed in the whole combustion process, will be stabilized.
The burning speed of the oil, and the initial temperature of the liquid, the tank diameter, the height of the liquid in the tank, the water content in the liquid, the nature of the oil and other factors. The higher the initial temperature, the faster the oil combustion rate; low level in the tank than the high level when the combustion rate is fast; water-containing oil than the water-containing oil combustion rate is slow.
2. High flame temperature, strong radiant heat
Oil in the event of combustion will release a large amount of heat, so that the temperature around the fire, resulting in the spread of fire and expansion, so that it is difficult to fight personnel close to the fire extinguishing work has brought difficulties.
According to the test, the tank fire, the flame center temperature as high as 1,050 ~ 1,400 ℃, the tank wall temperature of 1,000 ℃ or more. The intensity of heat radiation from the tank fire is proportional to the time of the fire, and the calorific value of the burning material, the temperature of the flame. The longer the burning time, the stronger the radiant heat; the greater the calorific value, the higher the flame temperature, the greater the intensity of radiant heat. Strong thermal radiation easily caused by neighboring tanks and other combustibles burning, at the same time, seriously affecting the fire fighting action.
3. easy to flow and spread to form a large area of fire
Oil is easy to flow of liquid, with the flow of diffusion of the characteristics of the fire with the destruction of the equipment, it is very easy to cause the flow of fire diffusion, and oil in the event of a fire and explosion is often caused by the destruction of equipment, such as the top of the tank to blow up, the tank wall rupture or with the rising temperature of combustion, such as the collapse of the deformation. Therefore, the oil fire, attention should be paid to preventing the flow of oil diffusion, to avoid the expansion of the fire.
4. easy to boil overflow
Storage of heavy oil tanks on fire, sometimes caused by oil boiling overflow. Burning oil spillage, and even from the tank sprayed violently, the formation of a huge column of fire, can be as high as 70 ~ 80m, the column of fire downwind jet distance up to 120m or so, this phenomenon is usually referred to as "boiling overflow". Burning tanks once the "boiling overflow", not only easy to cause casualties fighting personnel, but also due to the increase in radiant heat from the fire, causing neighboring tanks burning, expanding the disaster.
5. explosion hazard
Oil at a certain temperature can evaporate a lot of steam. When these oil vapors and air mixed to a certain proportion, encountered an open flame that is an explosion. This type of explosion is called chemical explosion. Oil storage containers in the flame or under the action of high temperature, the oil vapor pressure increases dramatically, in excess of the container can withstand the limit pressure, the oil storage containers occurred in the explosion, called the physical explosion, in the oil fires, sometimes the first physical explosion, the container of combustible vapors rushed out of the chemical explosion caused by the shock wave or high temperature, high pressure, equipment, containers, physical explosions; and sometimes is the physical and chemical explosions intertwined.
6. with re-ignition, re-explosion
Oil fires in the case of fire extinguishing without cutting off the source of liquid, meet the fire or high temperature will produce re-ignition, re-explosion. For the fire after the tanks, pipelines, because of its wall temperature is too high, if not continue to cool, will re-create the burning of oil.
(B) oil depot fire fighting methods
1. Organization and command
(1) organization of water supply to the fire, enough fire extinguishing agent and fire-fighting equipment. Fire water supply is the basic guarantee to fight the oil depot fire, to designate a person responsible for the specific implementation of the water supply, to determine the optimal method of water supply, to ensure an uninterrupted supply of fire extinguishing and cooling water.
(2) often keep in touch with the teams, master intelligence information, rapid decision-making, and give orders.
(3) fighting the oil depot fire should emphasize the centralized unity, coordination and coherence, the launch of the attack should be unified by the commander of the order, the implementation of the general attack.
2. Reconnaissance judgment of the fire
The oil depot fire, the fire is very violent, instantly will be rolling smoke, the formation of a blaze, intense radiant heat, ferocious fire, a serious threat to the firefighters, neighboring tanks and other facilities of the safety.
Correct judgment and estimate the fire, as soon as possible to control the fire, prevent the fire from spreading, quickly extinguish as well as to protect the safety of personnel are very important. In the event of a fire, the following should be quickly identified:
(1) the type of fire tank, diameter, height, nature of the oil, oil storage height, thickness of the bottom of the water and the destruction of equipment and facilities.
(2) the environment around the fire, terrain, roads, and firewalls through the pipeline ditch situation and the lines available for attack
(3) the part of the fire, the form of combustion, oil spillage of oil, the degree of threat to the surrounding.
(4) observe the color of the flame, to determine the possibility of an explosion.
(5) the possibility of transferring the oil in the fire tank, fire breakwater and sewer water seal is intact.
(6) fixed, semi-fixed fire extinguishing device is destroyed, as well as the location of the hooked pipe set up foam.
(7) of the cave fire, should send a reconnaissance team, with fire clothing, with gas masks and lighting equipment, with the necessary detection instrumentation, quickly probe the hole oxygen content, harmful gas concentration, temperature and explosion, combustion location, damage, and so on.
3. Tactical principles of fire fighting
Once the oil depot fire, the fire situation is very complex, ever-changing. Fighting should be based on the specific situation to determine the specific tactics. No matter what the situation should be in the fire fighting, according to the characteristics of the oil depot fire, rapid control of the fire, to prevent the spread of fire, to ensure the safety of personnel as the primary task. In general, fighting the oil depot fire should pay attention to the following principles.
(1) first control, after the fire
After the oil depot fire and explosion, should try to ensure that the structure of the equipment is intact, the oil will be limited to stable combustion in the equipment, not leaking to expand the fire. Therefore, before making preparations to extinguish the fire, should immediately organize forces to cool the fire tanks and may endanger the neighboring tanks to control the fire, to prevent the spread of fire. Especially downwind direction of the tank, by the fire tank of the strongest radiant heat, tank wall temperature is often as high as 80 ~ 90 ℃. If not cooled, it is likely to be ignited, expanding the fire situation, resulting in a wider range of fires, bringing threats to the personal safety of firefighters.
On fire tanks and neighboring tanks for cooling at the same time, should also organize forces around the equipment that may be threatened, buildings for evacuation, demolition and oil crystals may be dispersed in the direction of the parts of the dike to block the flow, or will be dispersed oil guided to a safe place.
(2) concentrated superiority of forces, quick decision
The oil depot fire is different from the general building fire. Oil depot fire, burning speed, burning time is too long, easy to make the tank oil and gas mixture reaches the explosion limit, resulting in an explosion. Therefore, must be in the early stages of the fire to focus on superior strength, into the battle, trying to put out the fire in one fell swoop.
(3) do a good job of fire fighting precautions
In the whole process of fire fighting and rescue, must always put personal safety in the first place. Pre-consideration of the fire may appear in a variety of dangerous situations, both to be able to effectively fight fires, but also in a relatively safe position, once the life-threatening situation, to be evacuated in a timely manner.
4. Oil depot fire fighting steps
Fighting oil depot fire in principle, after three steps: cooling protection; fire ready; fire.
(1) cooling protection
Cooling is to control the fire, to prevent the neighboring tanks or buildings burning and exploding an effective method. Usually, the burning tanks and neighboring tanks and buildings should be cooled.
Cooling tanks, cooling water should be shot to the top edge of the tank wall or tank top, so that the water flows from top to bottom, play a comprehensive cooling effect; cooling water should be uniform, can not leave a blank spot, so as to avoid too large a temperature difference between the tank wall, caused by the tank deformation or rupture.
(2) firefighting preparations
The fire department arrived at the fire scene, in the oil depot cooling at the same time, to do a good job of attacking all the preparations for firefighting.
① Extinguishing agent. Foam liquid preparation should be prepared equal to six times the amount needed to fight a fire.
② water supply preparation. The use of pools and other water sources, the amount of water to ensure that to meet the needs of a fire, the middle of the water shall not be cut off.
③ do a good job of attacking the water gun cover ready. Attack will be blocked by high temperature and smoke, to organize spray water gun cross cover.
④ Wear good protective equipment. Wear insulated clothing, draped in wet quilts, wearing protective masks and so on.
(3) fire
Grasp the fire at a favorable time, under the unified command of the fire commander, each position at the same time to launch a fire will be extinguished in one fell swoop, do not do anything, sporadic attack, so that both waste of manpower and material resources, but also to achieve the purpose of extinguishing the fire.