Fire tetrahedron

The coneept of preventing the variables of the fire triangle from coming into contact with each other to initiate a fire is fire prevention. When a fire starts, it requires four variables to sustain combustion reaction. They are fuel, oxygen, heat, and chemical chain reactions. These four variables represent the fire tetrahedron. Chemical chain reactions are a product of the combustion process. 

Brooms, pipes, and other debris stacked around or against circuit breakers Containers of paint or solvent left unsealed and next to heat sources Collections of flammable debris that could become ignited or supply fuel to a fire starting from some other source 

frayed, or temporary wiring that could serve as an ignition point for fire Non-explosion-proof lighting, fixtures, switches, etc. in areas where flanunable vapors or dusts could accumulate and ignite Fire extinguishers that are inoperable or cannot be reached because of materials blocking access 

Unmarked or blocked fire exits or means of escape 

Exit doors that open inward, so that passage from the area is more difficult (Life Safety Code) 

The lower flammable limit, also known as the lower explosive limit, is the lowest concentration of gas or vapor (percentage volume in air) that burns or explodes if an ignition source is present. The upper flammable limit or upper explosive limit is the highest concentration of a gas or vapor that burns or explodes if an ignition source is present. A mixture can have too little of the concentration (and be too lean) or too much of the concentration (and be too rich) to burn. In the case of the boat repair shop, the concentration was between the limits, so it ignited. Incidentally, the closer the mixture gets to the limits, the less complete the combustion. The optimal mixture for complete combustion is near the midpoint between the limits. 

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A more scientific representation is a fire tetrahedron with the combustion chemical reaction considered as a fourth parameter or side of the tetrahedron. 

Fire Tetrahedron A four-sided, solid geometric figure Uiat resembles a pyramid, with one of the sides forming the base. Each side indicates one of the tour elements required to have fire. 

Earth (cube) water (icosahedron) water air (octahedron) air fire (tetrahedron),... 

The roots of molecular beauty can be traced back to the Platonic tradition. To Plato, the most beautiful bodies in the whole realm of bodies were the tiny polyhedra, now deemed the Platonic solids, which he proposed comprise the universe the four elements - earth (cube), fire (tetrahedron), air (octahedron), water (icosahedron) - and the ether (dodecahedron) (Fig. 1). Joachim Schummer, who has written [9] extensively on chemical aesthetics, writes ... 

Trichlorosilane DPR is known to produce shock-sensitive hydrolysis products. Because these popping gels contain all four necessary elements of the fire tetrahedron, fuel, oxidizer, sustainable reaction, and ignition source, they pose a significant hazard, particularly in classified areas or wherever flammable atmospheres may exist. 

Fire tetrahedron showing the four necessary conditions required to sustain combustion. 

To understand what extinguisher to use, and why, we should next learn about the fire triangle and the fire tetrahedron. 

FIGURE 2.1.2.2 The Fire Tetrahedron. The fire tetrahedron helps explain how fires can be extinguished. 

The chain reaction is the least obvious component of the fire tetrahedron since this is occurring at the molecular level and we don t observe it directly. The exact mechanism by which chemicals burn is complicated but we know it involves a catalytic chain reaction. Some extinguishers work not by removing fuel, oxygen, or heat but by interfering with the chemical reaction in a fashion that stops the fire. 

The value of understanding the components of the fire tetrahedron is that removing any one of the components stops the fire. 

Water extinguishes a Class A fire primarily by cooling the burning fuel. Type A extinguishers are not likely to be found in laboratories. This removes the heat from the fire tetrahedron and the fire stops burning. (See Chemical Connection 2.1.2.1 Why Firefighters Love Water.)... 

What part of the fire tetrahedron was not originally included in the fire triangle ... 

We assume that you are also familiar with the fire tetrahedron, as described in Section 2.1.2. Understanding the fire tetrahedron helps one to understand how various fires burn and how to extinguish them. 

During the process of combustion of vapors and gases in which there is a visible flame, a better model is the fire pyramid. Some call this the fire tetrahedron, since there are three sides and a base in the fire pyramid concept. Figure 16-Ib shows a fourth component, production of hydroxyl (OH) radicals. An uninhibited reaction breaks down molecules into hydroxyl radicals. They last for an extremely short time, typically about 1 ms. 

These are the four methods by which all of the available fire extinguishers control fires from candles to forest-fires. A pictorial presentation of die fire tetrahedron has been developed from the fire triangle [Sutton 2004], For ease of... 

Developing the parallels with the original fire tetrahedron further indicates that accident initiation should be prevented if ... 

The fire tetrahedron indicates that if any of the elements is sufficiently reduced the propagation of the fire ceases and the full flame phase of the fire is prevented. One can envisage fire safety case reports using the fire tetrahedron as a basis, where for each operational mode of, for example, an off-shore fire management system, where the occurrence and significance of each tetrahedral element is judged to determine a level of risk priority. In turn each operational mode of a system is assessed to see if one or more of the four tetrahedral elements can be removed completely, or reduced to a level that would prevent fire propagation. 

These four requirements are often represented as the fire tetrahedron, see Fig. 7.4. 

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