Fire fighting tactics of the hottest LPG fire

2022-08-14
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Fire fighting tactics of liquefied petroleum gas

liquefied petroleum gas is a kind of light, excellent and pollution-free fuel after use. In 1912, the first domestic liquefied petroleum gas stove was developed in the United States, and since then, liquefied petroleum gas has been gradually used by people. In 1965, it was first popularized and used in Beijing, China. In addition to being used as industrial raw materials, liquefied petroleum gas was widely used as fuel. Since the advent of liquefied petroleum gas, all kinds of accidents have occurred. Due to rapid combustion and violent explosion, it is very easy to cause casualties and heavy economic losses. On March 5, 1998, the flange seal on the upper part of the blowdown valve of No. 11 spherical tank in the storage and irrigation area of the liquefied petroleum gas Management Institute of Xi'an gas company partially failed, resulting in a large amount of leakage of liquefied petroleum gas, and deflagration in the event of sparks after diffusion. The fire caused 12 deaths and 30 injuries, and direct property losses of 4.778 million yuan. Dealing with liquefied petroleum gas accidents is often encountered by public security fire forces. Therefore, it is of great practical significance to study and master the disposal technology and tactics of such accidents

I. General characteristics of liquefied petroleum gas:

1. Composition of liquefied petroleum gas:

the main components include propane, propylene, butane, isobutane, butene, isobutene and other low molecular types, while the main components of Civil liquefied gas generally treated are propane, n-butane and isobutane

2. Physical and chemical properties; The solution to the failure of impact testing machine is: 1 The jaw is not placed properly when clamping

LPG is gaseous under normal pressure, with gas properties, and becomes liquid after cooling and pressurization, with increased density. Liquid liquefied gas is highly volatile. When it volatilizes into gas, its volume expands 250-300 times, its calorific value is large, the maximum combustion temperature can reach 1900 ℃, the volume expansion coefficient is about 10-16 times that of water, and the relative density is 1.56 times that of air. It is easy to deposit in low-lying places

II. Fire characteristics of LPG:

1. Combustion characteristics: when LPG is burned in gas phase, the pressure is high, the air flow is large, the combustion is violent, the thermal radiation is strong, and a bright light yellow flame is emitted. For example, when there are many impurities in the gas, the flame star changes periodically, and a large number of incomplete combustion products are generated

2. Explosion characteristics: LPG has a great explosion risk. When it is radiated by the sun at high temperature or heated by other heat sources, it is extremely explosive due to the rise of pressure. After explosion, it is extremely powerful. The explosion speed is m/s. The explosion of 1kg LPG is equivalent to the power of kg TNT explosive, and it is accompanied by deflagration, which is easy to form a secondary explosion, form a large-area fire, and cause heavy losses

III. technical and tactical measures for fire fighting

1. Treatment of gas leakage accident

gas leakage often refers to the leakage of gas from the storage tank in the liquefied gas station in today's Germany due to valve damage, pipeline rupture or storage tank rupture. It is extremely dangerous because it is easy to cause deflagration

(1) close the valve, cut off the source and block the leakage point. In case of gas leakage accident, the valve shall be closed quickly, the gas source shall be cut off, and corresponding methods shall be taken according to the situation: if the valve is damaged, wet hemp sheet or quilt shall be used to wrap the leakage place, and the valve shall be replaced immediately. If the pipeline is broken or the storage tank is broken, the leakage shall be stopped immediately with a wooden wedge, and the valve shall be opened at the same time to guide the leaked liquefied gas to other storage tanks, so as to reduce the pressure and reduce the risk

(2) start the automatic spraying or cooling equipment to cool the pipeline or storage tank while dispersing the leaked gas

(3) control the fire source to prevent accidents. After gas leakage, all ignition sources in the gas diffusion area should be extinguished, the power supply should be cut off, production activities should be stopped, irrelevant personnel should be strictly restricted from entering the leakage area, the number of safety technicians and firefighters in the accident management site should be reduced as far as possible, and it is forbidden to bring in and use mobile, non explosion-proof speakers and BPs, and change rubber soles or cloth shoes to prevent static electricity from causing fire and explosion accidents

(4) set up a warning line at 50m outside the diffusion area, relatively block the traffic at the main intersection, prohibit irrelevant personnel or vehicles from entering, and quickly evacuate the downwind direction or nearby residents

(5) after the fire service vehicles arrive at the scene, they are not allowed to enter the warning area rashly. They should stop in a safe area, use flowering or spray jets to disperse the combustible gases deposited in the air and deep depressions, so as to dilute the content of combustible gases in the air, be prepared for combat, and deal with possible accidents in time

(6) after the danger is eliminated, the combustible gas content in the leakage area should be detected to make it less than 1.5%. When it reaches the normal value, the warning can be lifted and production can be resumed

2. Handling and precautions of fire accidents that make it difficult for many people to distinguish between true and false

when a fire occurs in the valve, pipeline or tank due to gas leakage, which causes combustion, all measures should be taken immediately to prevent backfire and deflagration. The specific matters are as follows:

(1) strengthen the cooling of structural objects, start fixed fire-fighting facilities, cool the tank and pipeline, and reduce thermal radiation. Firefighters should strengthen the cooling of the tank or adjacent pipelines, and the cooling should be uniform without leaving blank points. During cooling, the minimum flow rate of the water gun shall not be less than 6.5 L/s, and it shall be cooled continuously without interruption. The water gunner can shoot the cooling water directly to the top of the fire tank, valve and pipe to make the water flow down by itself, so as to strengthen the cooling intensity

(2) strengthen the protection of commanders and soldiers and reduce the harm of thermal radiation to human body. Front line commanders and fighters in areas with high temperature should wear fire-proof and heat-insulating clothes, and organize water gun defense lines along the main roads. Rear personnel should shoot water at front-line personnel for cover, so as to enhance the cooling protection of front-line personnel

(3) actively organize personnel to evacuate adjacent bottles to prevent the explosion of canned bottles caused by high-temperature radiation

(4) quickly cut off the gas source, prepare for plugging, and put out the fire with dry powder or high-pressure water flow. If it is impossible to cut off the dangerous source, strengthen the tank to make it burn stably, and extinguish it by itself after the liquefied petroleum gas is burned

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