I. Introduction

In December 2010, belonging to firefighters American Association for the Study UL safety laboratory (UL Firefighter Safety Research Institute) in strong support of the US Department of Homeland Security, conducted a series of really building fire simulation, based on the experimental results, published “Experimental report on the effect of smoke exhaust on fire characteristics of modern and traditional homes”.

Stephen Kerber was the first author of the report. The publication of this report has aroused strong repercussions in the US fire-fighting community. Fire-fighting organizations have begun to re-examine the characteristics of modern fires, assess fire risk, improve tactical use, and combine scientific data and conclusions to gradually overcome misunderstandings of past empiricism and enhance the ranks. Fire fighting and rescue efficiency and firefighters self-rescue capability.

Fire characteristics are the hottest topics in the United States for the past decade. Enhancing the firefighters' learning of fire characteristics aims at enabling firefighters to make scientific and accurate judgments on the fire field and formulate realistic firefighting and rescue tactics. As a translator, I know that firefighters in China and the United States face considerable differences in the risks and environments they live in, but the fire characteristics are similar. I hope that my fellow colleagues, after learning this article, will be able to achieve great results in the actual battle.

Compared with the original text, the translation of certain chapters, pictures, and appendices has been deleted, but it does not affect the rationality of the final conclusion. As far as the level of translation is concerned, I am only able to strive for perfection and try my best to use words and phrases to express the meaning of the original text. If any translation is inaccurate, please criticize and correct me.

Second, brief introduction

Ventilation and ventilation are common fire control and fire fighting tactics. In actual combat, the smoke is defined as the upper part of the offensive entrance or the opposite side of the offensive entrance. By opening a hole to exhaust the smoke and heat of the fire, it helps the firefighters find fire points and extinguish the fire. If the smoke tactics are applied properly, the visibility of the fire can be increased, and the chance of flashover and rekindling can be reduced. If the smoke tactics are not properly applied, not only will it be more difficult to extinguish fires, but it will also cause rekindling or smoke explosions. At the same time, the increase of heat in the fire will lead to the occurrence of flashovers. The improper opening of smoke vents or untimely smoke exhaust will increase the air content of the fire , causing the fire to rapidly expand, spread, and potentially threaten the safety of firefighters located between the fire point and the smoke outlet.

The U.S. Department of Homeland Security, the International Committee of Fire Chiefs, and the International Association of Fire Fighters jointly organized Website, to search for accidents where firefighters are lucky to escape. Numerous reports on this website indicate that the exhaust smoke, sudden changes in the fire, and flare-ups are important reasons for the firefighters being at risk.

There are several cases in the report:

1. advancing to the living room, the room temperature by about 350 (176 ℃), quickly rose to 800?? (426 ℃), black smoke in a very short period of time, we immediately retreat out. The heat of the fires deteriorated. I felt my shoulders, legs, and neck start to burn. I turned to find the orange flame on the wall and the whole room began to burn. The firemen and I managed to cross the corridor and quickly left the building.

2. This is a converted garage. The ceiling is 15 feet ( 4.57 meters ) from the ground . The windows in the room have turned black. This gives us a clear indication that this room may have returned to fire. I conducted the coordination of ventilation, smoke and fire by radio command. When we opened the door and started the attack, I noticed that the entire room was burning and the fire had enveloped us. I ordered the team to retreat and prepare for redeployment. At this time, flashover occurs, burning entire wall of fire came at us, pushing to the impact of the three 225 lbs (102Kg) weight firefighter. In fact, we are likely to be more seriously hurt in this accident, but we were lucky to retreat and suffered only 1-2 degrees of burns. ”

3. When we arrived at a two-story house, we found that a lot of smoke came from the second floor and there was no open fire. We carry a diameter of 1.75 inches (44.45mm) of the hose into the room, and the stairs to the second floor. We entered the 2nd floor to begin search and rescue and find fire points. We informed the commander that we needed to ventilate and smoke, and sent more force to support it on the second floor. Suddenly, smoke and heat increased, and we were forced to retreat to the second floor staircase. My commander immediately told me to open the window of the stairway. At that time, I did not think much about it and opened the window. Suddenly, the explosion happened, and we instantly pushed down the stairs from the 2nd floor to the 1st floor, accompanied by a huge fireball."

4. We arrived at a two-story house with a residential area of ​​approximately 3,000 square feet ( 278 ?).. When the back of the building began to smoke, I opened the front door of the house and the smoke was quickly sucked back into the room. I kneeled on the ground, looking inside the room and trying to find something. I decided to go inside to find the fire. When I got inside the room about 8 feet ( 2.4 meters ) away, I stopped because a lot of flames fell to the floor. I found that the smoke color faded and I was able to see the roof. All I saw was the flame. These combustible gases burned at the top of the building and I decided to evacuation from the inside quickly. When I came back, I saw the fire tongue pulled out about 12 feet ( 3.65 meters ) from the door . The second hose was laid and began to extinguish. This gave me the opportunity to stay away from the fire building. When I was in place again, the two water guns fired at the door and the front window, respectively, and the entire living room was already in full combustion due to flashover.

5. We withdrew from the scene and reported the situation on the scene to the on-site commander and implemented ventilation and smoke exhaust. Two large windows in the same room had been broken and the indoor smoke layer had risen by 3-4 feet ( 0.9-1.2 meters ).” We entered the room again, just past the location of the first attack, and the entire room was There was a flash of fire, and my squirters disappeared into flames except for their feet, and I could barely see the entrance, because we were surrounded by fires, and I dragged my companion's feet back to the door. Initially, he was more resistant to dragging him out of the fire because he had already rolled to the ground and turned on the water gun in an attempt to extinguish the fire, but this had no effect on the fire. The outdoor comrades saw the fire blew out of the window next to us. We arrived at the scene to help us withdraw.

In the early stages of the fire, due to the airtightness of the room, it is possible to form a ventilation-limited fire field. If the indoor airtightness is good, the fire is likely to extinguish itself, because the combustion exhausts the indoor oxygen. Similarly, if the interior of the room is ventilated due to tactical needs of the firefighters or due to high temperatures causing the window to break, oxygen will enter the room and the heat generated by the fire will increase, and flashing may well occur. Changes in the fire conditions caused by ventilation and smoke, sometimes surprisingly quickly, make it difficult for firefighters to respond in a short time.

Due to changes in the modern housing situation (including newly developed construction materials and building construction, indoor combustibles, new house size and indoor geometry), ventilation and smoke emissions will result in more pronounced changes in fire power. Many modern residential buildings are larger than older buildings, and newer homes are more open-planned and large-space floor designs, which will increase the rapid spread of fire. As a result of major changes in indoor combustibles in recent years, the rapid spread of fire has been further exacerbated. These changes include: the increase in flammable composite materials such as plastics and textiles, and the increase in the number of commodities with combustibles and unknown components and uncertain combustion characteristics. Next, look at the two experiments in today's article.

This article comes from Micro Signal Orange Rescue.