## 1 Introduction
### Features of Fires of Organic Compounds
#### 1.1.1 Features of Combustion of Organic Substances  
In the process of the combustion of organic polymer compounds, the formation of various final products is possible [26; 27]. So, for example, in the general case, the burning of plastic (polyethylene and polypropylene) is accompanied by the formation of such substances as carbon dioxide, water, carbon monoxide, methane, and soot. The chemical equation will have the form (1):  
\[(\mathrm{C_{2}H_{4}})_{n}+\mathrm{O_{2}}\rightarrow\mathrm{CO_{2}}+\mathrm{H_{ 2}O}+\mathrm{CO}+\mathrm{CH_{4}}+\mathrm{C} \tag{1}\]  
During combustion, polyurethane emits carbon dioxide, water, carbon monoxide, and ammonia, according to (2):  
\[(\mathrm{C_{3}H_{7}NO_{2}})_{n}+\mathrm{O_{2}}\rightarrow\mathrm{CO_{2}}+ \mathrm{H_{2}O}+\mathrm{CO}+\mathrm{NH_{3}} \tag{2}\]For natural textiles, for example, cotton (90% consists of cellulose), the combustion products include carbon dioxide, water, carbon monoxide, methane, and formaldehyde according to (3):  
\[(\mathrm{C_{6}H_{10}O_{5}})_{n}+\mathrm{O_{2}}\to\mathrm{CO_{2}}+\mathrm{H_{2}O}+ \mathrm{CO}+\mathrm{CH_{4}}+\mathrm{HCCO} \tag{3}\]  
During the combustion of mixtures of organic and inorganic compounds, processes of the simultaneous thermal decomposition of these compounds occur. For example, for plasterboard, the main process is the dehydration of gypsum CaSO\({}_{4}\cdot 2\mathrm{H_{2}O}\). Gypsum contains two molecules of crystallization water that are released during heating or burning. During this process, gypsum is transformed into anhydride, which is accompanied by the release of water vapor, according to (4):  
\[\mathrm{CaSO_{4}}\cdot 2\mathrm{H_{2}O}\to\mathrm{CaSO_{4}}+2\mathrm{H_{2}O} \tag{4}\]  
The combustion of paper (cardboard, wood, and cellulose) leads to the formation of carbon dioxide, carbon monoxide, methane, soot, formaldehyde, and acetaldehyde according to (5):  
\[(\mathrm{C_{6}H_{10}O_{5}})_{n}+\mathrm{O_{2}}\to\mathrm{CO_{2}}+\mathrm{H_{2}O }+\mathrm{CO}+\mathrm{CH_{4}}+\mathrm{HCCO}+\mathrm{CH_{3}CHO}+\mathrm{C} \tag{5}\]  
For engine (motor) oils consisting of a mixture of hydrocarbons, during combustion, carbon dioxide, water, carbon monoxide, and soot (6) are formed, as well as the formation of sulfur gas and unburned hydrocarbons:  
\[\mathrm{C_{x}H_{y}}+\mathrm{O_{2}}\to\mathrm{CO_{2}}+\mathrm{H_{2}O}+\mathrm{ CO}+\mathrm{C}+\mathrm{unburned hydrocarbons} \tag{6}\]  
At the same time, it should be noted that depending on the type of combustion (complete or incomplete) and temperature, with or without sufficient ventilation, etc., the chemical composition and output of one or another combustion product will vary significantly [28; 29]. Under the conditions of the presence of impurities in the polymer, the products of incomplete combustion may contain various additional halogens, phosphorus, nitrogen derivatives, etc. In addition, incomplete combustion products such as xylenes, naphthalene, styrene, chloromethane, etc., may occur [30]. At the same time, it is noted that natural organic products release fewer polycyclic aromatic hydrocarbons than synthetic plastics. The peculiarities of the course of fires of organic polymer compounds in closed rooms lead to the formation of various dangerous combustion products at different stages of the fire (smoldering combustion, early flame that is well ventilated, and fully developed flame that is not sufficiently ventilated). Due to the temperature regimes, the high speed of the reactions, and the scale, the last stage is characterized by the highest yield of toxic compounds [31]. Since organic compounds, including polymers, are known to have low fire resistance [32; 33; 34; 35], various compounds are added or various coatings are used to increase their resistance to heat. Thus, various additives to improve the properties of polymer compounds also affect their combustion processes.