【Breakdown Technology】Fire Breakdown Accident Treatment in Special Indoor Fire Conditions

The flashing and rekindling are two kinds of special fire behaviors that are common during the development of a building fire (how to be a flash fire). During the fire fighting, the suddenness and strong destructiveness of the rekindling and flashing fire seriously threaten the safety of firefighters performing firefighting and rescue missions, especially fire room breaks. When May 1, 2014, Xuhui District, Shanghai Longwu Road 2888, Lane Room 241 301 residents of the fire, two fire officers and soldiers to break the demolition to save people taking inside, the scene due to sudden flashover, the moment was a large number of high-temperature hot air Smoke thick smoke pushed into the open window, died building. 1994 March 28, a three-tier Manhattan apartment fire, three officers entered the room two-story platform, because one room door is forced open, and the sudden return to burning, instantly engulfed in flames.

At present, despite the development of domestic demolition technology, there are still many problems in the demolition of equipment and personal protective equipment. Due to the problems of large size, long size, and low pass rate, the traditional rescue tools and supporting equipment will cause firefighters to be unable to display in the densely smoked buildings and miss the best opportunity for rescue. Unexpected casualties. This article summarizes the various causes of fire and rescue rescue under the conditions of indoor flashback and rekindification, and proposes relevant countermeasures to reduce firefighters’ casualties in rescue fires in indoor fires, which will increase the safety of future fire fighting and demolition of buildings. Guiding significance.

Germany Lucas rescue tool

1 Analysis of causes of indoor fire rescue accidents

1 . 1 direct cause

1 . 1 . 1 The destructive nature of its own harm

The flash fire is the phenomenon that all combustibles under the action of heat radiation ignite at the same time when they are flashing. The flame spreads quickly and spreads in all objects in the room, and the interior of the house forms a sea of ​​fire. In the event of flashover, the high-temperature smoke generated will have a serious impact on the safety of building structures and rescue operations, mainly in the following areas:

(1) The fire rescue personnel arrive at the scene before the flash fire. If the flash fire is not predicted and detected in time, the sharply rising temperature and flames may cause harm to the firefighters. With the development of modern fire detection technology, the time for discovering a fire is getting shorter and shorter, and more and more firefighters arrive at the fire scene before the flash fire occurs. As the research on the prediction of flashovers is limited to academic theory, there are no instruments available for the rescue site to make predictions or reconnaissance. Commanders can only rely on their accumulated experience in extinguishing fires to make initial judgments on the fire at the scene, which can easily lead to in-situ decision-making with low efficiency and low quality, and even make erroneous decisions, causing unnecessary human casualties and property losses.

(2) Before the flashover occurs, a large amount of accumulated smoke and high temperature will force the firefighters to bend over or move forward, which will cause great obstacles to the indoor demolition. In addition, the dense smoke that accumulates indoors makes the visibility in the room very low, which is very detrimental to the demolition and search and rescue operations. Difficult personnel cannot safely evacuate on their own, and firefighters also risk entering dangerous areas and getting lost. After the detonation, it turned into a full-scale combustion, burning more violently, unable to carry out in-depth indoor rescue, and due to the rapid increase in the burning rate, a large amount of toxic gases will be generated due to incomplete combustion of the fuel, resulting in trapped persons poisoning, suffocation, and more time for firefighting and rescue. Urgency, evacuation of personnel is more difficult.

(3) When the interior is equipped with a flashing ignition condition, it usually occurs after 3 to 10 minutes of ignition, and a high temperature of about 1000 °C occurs. After the fire brigade rushes to the fire site, the room may be about to start flashing due to the first amount of power. Insufficient estimates of the fire situation, personnel often arrive at the fire site in line with the "save the people first" principle, ignoring the investigation of the indoor fire, in the absence of timely evacuation will be sprayed out of flames and hot air out of the burning room , causing unnecessary casualties. Foreign media reported that some firefighters sacrificed each year due to flash fire.

1 . 1 . 2 Rekindling its own harmfulness

Rekindling is a kind of rapid burning phenomenon in which an indoor fire produces unburned pyrolysis products due to lack of oxygen and mixes with the air entering the room. When the firefighters implement the demolition, they are vulnerable to irreversible effects due to improper operation ( such as the sudden opening of the door ) . The main reasons are:

(1) Many buildings have good airtightness. When a fire breaks out, it is difficult for the indoor air to support combustion and lead to oxygen-depleted smoldering. After the firefighting force arrived at the scene, it lacked a rational understanding of smoldering and could not be aware of the smoldering phenomenon that was taking place. In order to quickly implement rescue and rescue operations, it opened up rescue routes and blindly opened doors and windows, resulting in sudden changes in ventilation conditions, resulting in a large number of Sudden entry of fresh air prompted the rapid acceleration of the initial fire to become flash fire or deflagration, which would threaten the lives of rescue workers in a short time.

(2) After the indoor fire is over, due to the continuous high temperature, the combustibles will still undergo a pyrolysis reaction and gradually accumulate a large amount of combustible gas and incomplete combustion products. At this time, once the demolition, the ventilation conditions are improved, and the air will be in the form of gravity flow. Combine it with the combustible gas in the room. When the air-fuel mixture is ignited ashes, it will form a 500 ~ 600 ℃, even 1O00 ℃ of temperature. For a typical building, whether it is a brick wall structure or a concrete or steel structure, it is easy to cause the destruction and collapse of the building components, causing secondary damage to the demolition personnel.

1 . 2 indirect causes

1 . 2 . 1 Demolition equipment congenitally lack of design

(1) The hydraulic pipe is too short. Hydraulic rescue equipment is generally equipped with only a fixed length of hydraulic pipe. If the site environment is complex or it is demolished on a damaged building, the power source must be lifted to the rubble, which increases the risk for the combatants under the demolition. The power station is too close to the operation point, which brings a lot of inconvenience to the combat personnel to carry out rescue work.

New hydraulic power station

(2) Operation is difficult. Take hydraulic breakers as an example, the tool can provide a strong demolition force, but it must have a certain weight, long-time demolition of the combat personnel is too much physical exertion, and does not install auxiliary attachments, to help personnel unable to start, support Too much vibration above the pole, more difficult to laterally break.

(3) Operating space restrictions. Such as the hydraulic circular saw is too large, the structure is not compact enough. It is very inconvenient to work in a narrow space. Especially in the hollow due to the limitations of the internal space, the cutting equipment must be small and flexible, strong demolition, and easy to get stuck when the reinforcement is tight. Protective cover, saw blade can not cut the object can not be cut.

(4) There are limitations in use, and there are incomplete varieties of rescue equipment. Such as diamond chain saw cutting the concrete structure, need to continue to use water to cool, and generally close to the source of the accident is difficult to find the site. At the same time, the matching accessories are not in place, and the water pipe joints are not compatible with the existing equipment and cannot be used without effective water supply. In addition, the emergency rescue situation is varied, and the required rescue equipment also changes with the situation. However, the existing types of rescue equipment are not complete, which seriously affects the rapid and efficient rescue.

(5) Repeated equipment functions, power supply and interface are not uniform. For example: hydraulic multi-function pliers with expansion, shear and traction, can replace the dilator , shears . In the face of the emergency rescue function given by the new Fire Protection Law, the fire brigade needs more and more mobile and electric equipment. The interface between electric, pneumatic, and hydraulic rescue equipment is not uniform and cannot be used in a mixture of equipment. This inconveniences the rescue work.

Germany Lucas hydraulic multi-purpose pliers

1 . 2 . 2 lack of practical experience in the demolition

(1) There is less daily training and practical experience is not abundant. Squadron leaders are afraid of accidents or fear of equipment damage and do not organize training. They are only demonstrated by veterans. New recruits lack operational opportunities. In order to ensure rapid rescue in actual rescue operations, the use of rescue equipment is generally concentrated in the hands of well-trained veterans in order to achieve the purpose of rapid rescue, and recruits lack practical opportunities.

(2) Lack of specialized training facilities and venues. In the actual training, due to the lack of specialized training venues and facilities, there is an embarrassing situation in which no things can be broken and nothing can be saw in the training, and training will only stop at the stage that will start the rescue tools.

1 . 2 . 3 personal protective measures are not in place

(1) The protective equipment is not matched and lacks systemicity. Firefighters did not form a complete set of equipment for personal rescue equipment. The quality and level of equipment were uneven. Some severely damaged personal protective equipment was still stored as inventory equipment, and even used for duty.

(2) The procurement of protective equipment is not strict. In bidding procurement, similar products in government procurement are easy to bid at a low price, and equipment with good quality and reliable equipment for officers and soldiers cannot win the bid due to high prices, and the performance, quality, and expected results of purchased equipment vary greatly. Some tenderers colluded with the bidders, and the bidders collaborated with each other and used false tricks and other unfair methods to defraud the winning bidder. As a result, the quality of purchased equipment is poor, the price is high, and its practicality is low. This has caused great damage to the front-line troops' rescue work.

(3) Do not use or use protective equipment. Some grass-roots combatants are afraid of training damage to equipment and equipment. They do not often organize and familiarize themselves with operations, resulting in difficulties in forming the best fighting power of people and equipment. Some commanders think that they have sufficient experience and are unwilling to use personal protective equipment, or improper use of personnel causes unnecessary deaths and injuries; Some firefighters are too "idealized" about the performance of protective equipment and do not consider actual factors.

(4) Use training blank. The new personal protective equipment is not only expensive, but also has high requirements for routine maintenance. Training can easily overlook the inspection and maintenance of the equipment. As a result, the performance of certain equipment is rapidly reduced. In addition, at present, training for grassroots squadron equipment is mostly performed by ordinary cadres, and professional equipment management and training of maintenance personnel are few. As a result, the use of equipment performance management training content is too small.

2 Firefighters rescue countermeasures to reduce casualties

2 . 1 At any time to detect special fire behavior signs

For flash fires, the alarm signals are mainly high-temperature radiation, "flashing" and "white smoke." If conditions inside the room are investigated, if the temperature of the indoor smoke is low, then there is no possibility of flashing, and the flower water should be cooled in time; if firefighters enter, they are obviously exposed to high temperatures and the hot smoke layer is continuously thickened. , indicating that there is a risk of flash fire, it should be evacuated to the outside to control the fire. At the same time, when entering the room, firefighters should also pay close attention to whether there is thick smoke from the doors and windows, overflow, whether the inclusion of smoke in the smoke with a smaller flame and flashing phenomenon, if these signs, then this room has a flash fire risk .

For rejuvenation, the warning signal is mainly to generate a large amount of black and red smoke, which is emitted from the doors, windows and holes. If you do not make adequate rescue preparations for rescue, do not open doors and windows easily, so as to avoid the influx of fresh air and accelerate the development of fire. At this time, the smoke outlet can be opened in the ceiling of the room or the upper part of the wall to directly discharge the combustible fumes to the outside, which will help reduce the mixed concentration of smoke and air. At the same time, when opening the vents, water gun positions should be provided in the openings to reduce the temperature of the flue gas and prevent the pyrolysis gases from igniting the adjacent targets, thereby reducing the possibility of the smoke igniting. When a relatively closed indoor fire is extinguished, and the site is unable to remove the pyrolysis gas in time, firefighters should not enter it and should consider entering it on the premise that the fire site is sufficiently cooled.

2 . 2 Reasonable selection and optimization of design demolition equipment

(1) Reasonable selection of rescue equipment. According to the actual situation in the emergency rescue, choose the most practical rescue equipment. At the same time, it is necessary to strengthen daily training to simulate different disaster accident scenes so that fire fighters can choose the most reasonable rescue equipments at the first time after they arrive at the scene, quickly carry out rescue and rescue, and protect the safety of life and property of the country and people.

(2) Optimize design and rescue equipment. For example, to increase the hydraulic pipeline, if necessary, to use the quick connector, according to the situation, can also be used as a spare pipe, so that the power station and the operating point to maintain a sufficient safety distance. Remote operation while moving the hydraulic pump can be reduced to be provided with a hydraulic oil tank oil level display apparatus easy to observe and grasp the situation of the fuel consumption, the pressure of the hydraulic pump outlet pressure gauge should be recommended to install, easy to check the pressure of the hydraulic pump, always Maintain the normal state of the pressure pump. Organize R&D of power sources that integrate multiple functions into a single unit. Only two devices, on-board and mobile, are required to provide sufficient power for all related equipment.

2 . 3 Master professional personal protection technology

For a flash fire, it is suggested that before the rescue personnel enter the rescue room, the tasks of each team should be determined according to the location and the number of people trapped. Each search and rescue personnel should wear fire fighting clothing, wear fire protection suits when necessary, wear air-breathing respirator , and carefully enter the water guns in the follow-up protection. In search and rescue, pay attention to checking whether there are coma people near the doors and windows. When the temperature of indoor smoke is too high, it cannot enter the fire field too far. It strictly follows the operating time and returns on time. If the flaring of the fire floor has already occurred, do not blindly enter the room. Try to ventilate and dissipate the heat, control the fire, and open the rescue passage appropriately. Then wait until the fire is reduced and then attack and rescue.

Air breathing apparatus

For rekindling fires, it is advisable to spray fine mist outdoors before opening doors and windows. When opening windows and doors, the speed should be slow, so as to avoid the risk of air entering the room below the pressure-neutral layer and increasing the risk of backfire; then, before the doors and windows are fully opened, spray water mist on the upper plane.

2 . 4 Improve training facilities and training programs

(1) Strengthen training and increase opportunities for practice. Establish a scientific and complete training plan, reform the training methods of the group, and adopt a combination of centralized training and decentralized training to focus on training. With the advantage of the training base, the role of the training team is fully utilized. According to the requirements of the annual training plan, a pair of different levels of personnel training in phases to ensure the completion of training quality and training plan.

(2) Improve training facilities. Reform training methods, build training bases and simulation training facilities, and develop simulation training equipment that replaces expensive and vulnerable equipment. By setting up modern methods such as the simulation environment and complex scenes, we have broadened the training path and improved the on-site disposal capabilities of combatants. Each of the corps and detachment sets up a demolition equipment training base according to their own specific conditions to simulate emergency rescue work under earthquake, car accidents, and housing collapse. Each squadron regularly organizes personnel to go to the base for training so that combat personnel can skillfully use the equipment and equipment in their hands in various situations, so that rescue work can be done quickly and efficiently.

3 Conclusion

The rescue and rescue operations under firefighting and rekindling conditions are relatively risky. It is necessary to fully grasp the critical conditions, signs of occurrence, and preventive measures. At the same time, improvements in the performance of demolition materials and personal protective equipment are necessary and effective. The actual combat training, only the combination of the three can minimize the casualties of such officers and soldiers.

This article comes from "Fire Safety" in 2015 the 9th period, re-edited by China Rescue Equipment Network.