Annually, the residential sector accounts for about 70 % of the total number of fires in the Russian Federation. In the apartment houses killed more than 90 % of the total number of deaths in the Russian Federation. Factor that significantly increases fire hazard in high-rise buildings is the high probability of late detection of fire in case of absence or being in a failed state of systems of fire automatics. Currently, the design of residential high-rise buildings in the Russian Federation is regulated by the requirements of Set of rules 54.13330.2011 “Residential Buildings. The updated edition of SNiP 31-01-2003”. By US regulations automatic detection and notification of fire is necessary in almost all residential buildings. In accordance with the NFPA standards, all new apartment buildings should be protected by automatic fire extinguishing systems. The widespread implementation of the automatic fire extinguishing systems in residential buildings in our country is hindered by the lack of regulatory framework. In 2016 Set of rules 267.1325800.2016 “Buildings and complexes high-rise. Design rules” was developed, which contains a section on fire safety, mainly devoted to requirements of design solutions. Currently is developing a set of rules devoted to questions of fire safety of high-rise buildings. For fighting fires and conducting rescue operations in the high-rise buildings fire ladders, mobile aerial towers and helicopters are widely used. To supply fire extinguishing substances in high-rise buildings fire trucks with high pressure pumps and special hydraulic equipment are used. To ensure the removal of smoke from escape routes of people in some cases mobile smoke exhaustion equipment can be used. To ensure the safety of people at fires in high-rise buildings it is advisable: § consider the possibility of inclusion in the compulsory fire security demands the requirements of the protection of premises with fire alarms and automatic fire extinguishing systems; § to provide high-rise residential buildings with emergency rescue devices of group and individual actions, as well as isolating and filtering self-rescuers, depending on the conditions of use; to develop normative documents with demands of mandatory placement in a residential high-rise buildings of the technical means of human salvation; § to review the regulatory documents that define requirements for the construction of fire stations with their equipment of modern mobile firefighting and rescue equipment; § to develop a set of rules tailored to the fire hazard of high-rise residential buildings; § to provide the legal basis for the activities of fire service in the prevention of fires in the residential sector and primarily in the high-rise buildings.

The work is mainly devoted to the analysis of dust hazard features, whose test in a standard blasting chamber with a volume of 20 liters to 1 m³ leads to a maximum pressure P_max comparable to a value of 100 kPa. Such dust is suggested to be considered dust with a low explosion hazard, in contrast to dust with high explosion hazard ( P_max >> 100 kPa). The choice of the critical pressure level (»100 kPa), indicating the flame propagation over a considerable distance from the ignition source, is based on the analogy between the models of percolation theory and the simplified combustion scheme for a macroscopically inhomogeneous dust/air mixture. For dust with low explosion hazard (Poletaev, 2017), the limiting oxygen concentration (LOC) is close to the normal oxygen content in the atmosphere C_OX,0 = (20.7 ± 0.1) % by vol. It was proposed to use the parameter D_OX = C_OX,0 - LOC to evaluate the dust explosion hazard along with the standard parameter Pmax. It is shown that for dust with a low explosion hazard 0 < D_OX < 0.5 % by vol. An illustration of the conclusions of the work was carried out using the known results of a study in 20-l and 1000-l blasting chambers of three melamine samples with an average particle size dm of less than 10, 19 and 52 μm, respectively. It is shown that the mixtures of all the examined melamine samples with atmospheric air are non-explosive under normal conditions (absolute pressure 100 kPa, temperature 25 °C). To explain the non-explosive of melamine dust having a high calorific value (15.67 MJ/kg), it has been suggested that the volatile component of its thermal decomposition products (ammonia) is burned, which allows an analogy between the combustion of melamine and coal particles. On the basis of the fact that a study of dust in a 20-liter chamber is actually performed at elevated initial values of temperature and pressure (Cashdollar and Chatrathi, 1993, Poletaev, 2017), the temperature at which a melamine sample ( d_m = 19 μm) forms dust/air mixture with a high explosive hazard was determined (68 °C). The importance of this result is due to the fact that in the production of dispersed melamine, the finished product can be transported by air with a temperature of over 100 °C. In European standards EN 14034, the correction of the value of P_max obtained in a 20-liter chamber is proposed with the aim of predicting the value of this parameter, expected from the results of tests in a 1000-liter chamber. The above test feature in a 20-liter chamber makes such an adjustment erroneous in the case of dust with low explosion hazard. Taking into account this peculiarity and a number of empirical regularities of turbulent combustion of an dust/air mixture, an estimate of the minimum value of the index K_st , corresponding to the case of an explosion in a 20-liter chamber, is performed. It is shown that for a subcritical non-explosive dust/air mixture (LOC » C_OX,0) the transition to a state of high explosion hazard is possible with heating by only 10…20 °C.

The article raises the urgent issue - the lack of physicochemical properties of the new synthesized substances. These properties will allow employees of supervisory activities to develop fire safety systems at security facilities. The efficiency of such systems is achieved by eliminating the combustible environment or the ignition source. Using the example of oxygen-containing hydrocarbons, which are used practically in all areas of industry and are produced according to reference data in the amount of more than several tens of millions of tons per year, it was possible to predict the maximum explosion pressure, i. e. one of the most important fire hazard properties of a substance, with the help of a technique for predicting the fire hazard properties of oil refining products based on molecular descriptors and artificial neural networks. The proposed methodology is implemented using the author’s computer program “NeuroPacket KDS 1.0”. The program “NeuroPacket KDS 1.0” allows you to: download and view databases containing the tructures of chemical compounds and their properties; to correlate the input data; to evaluate the received models statistically; use the obtained neuronet models to predict the properties of substances without conducting a complex experiment. This approach to predicting the fire hazard property of refined products describes the structure of the molecule with the help of molecular descriptors and establishes quantitative correlations between the values found using artificial neural networks. Based on some reference data, data was verified. In addition, the maximum explosion pressure was predicted for substances that are not known in the reference and regulatory literature. This makes it possible to build on the values obtained in the development of fire safety systems. Based on the results obtained, the category of premises for explosion and fire hazard was calculated. It was found that the estimated value of excess pressure was less than the claimed value, and therefore the financial costs of developing a fire safety system would also be reduced. It should be noted that the methodology for predicting the fire-hazardous properties of oil refining products based on the use of molecular descriptors and artificial neural networks allows us to conclude that this technique can be used to predict other fire-hazardous properties of organic substances.

Emergency situations during transportation of petroleum products are caused by the formation of a combustible medium during draining operations and the further ignition of the vapor-gas mixture from discharges of static electricity. To date, the method of reducing the fire hazard of the transportation of flammable liquids is the development of technical and technological solutions to change the thermophysical and electrophysical properties of liquids. The methods of stabilization of ethanol-based nanofluids by means of a non-reactive modification of a liquid under the action of variable frequency modulated potential (VFMP) were investigated. It is established, for ethanol samples, at electrophysical action, the characteristic peaks shift by 10…20 cm^-1 in comparison with the unmodified liquid. The absence of nanoparticles in the surface layer of the liquid in a concentration sufficient for their identification was revealed. The results of measurements of the intensity of evaporation reflect that the evaporation intensity depends on the concentration of MWCNT and decreases during the first 4 hours on average by 24 % after the creation of the nanofluid. With electrophysical action, a significant decrease in the intensity of evaporation persists for 5-6 hours. This change is explained by the strengthening of Columbic repulsion force between the nanoparticles, which reduces the aggregation of particles and increases the stability of MWCNT in the liquid. The dependence of the electrical conductivity of nanofluids on the conditions for the stabilization of MWCNT nanoparticles in it consists in an increase in the concentration of MWCNT in the liquid, due to which its resistivity decreases by 48 %. However, within 2 hours, the resistivity of the nanofluid becomes similar to the base fluid. Under the influence of the VFMP, the process of agglomeration of the nanoparticles slows down, a slower (up to 3 hours) increase in the specific resistivity of the liquid takes place. Reduction of agglomeration of particles is due to the presence of an electric charge on the surface of nanoparticles. The data of the research results reflect the possibility of using carbon nanoparticles as additives to reduce the fire hazard of storage and transport processes of flammable liquids. The revealed time constraints for preserving the properties of nanofluids with specified performance characteristics will allow us to justify the application of technological solutions for additional stabilization of nanoparticles to ensure fire and explosion safety and electrostatic safety when handling flammable liquids.

Considering the development Set of Rules “High-rise buildings and complexes. Fire safety requirements” it became very important, first of all, the choice of means and methods to protect people from the impact of dangerous fire factors. The correct solution of these issues leads to the achievement of the primary objective of the technical regulation “protection of life and health of citizens”. The paper shows that these calculated values of fire risk focused on the parameters for automatic systems of fire protection and fire extinguishing equipment of foreign production, do not allow achieving this goal without evacuation of people. Calculations have shown, that the probability of a successful evacuation should be 0.999, while the probability of failure-free operation (or safety factor) of applied automated systems is about 0.8-0.9. At the same time, the analysis of the demographic data of the UN and WHO shows that the physical ability for the safety of pedestrian evacuation of the population in developed countries over the past decade has declined significantly and they continue to degrade in connection with the increase in the number of elderly people, rising disability among people and obesity spreading to all age groups. Consideration of these demographic trends leads to the inevitable conclusion about the necessity of improving the reliability and efficiency of functioning of the automated systems of fire protection. The paper summarizes the presentations of Russian scientists and domestic manufacturers of these systems, showing that over the last decade they’ve managed to make a number of innovative inventions that are currently able to provide the domestic market with the products, which many times exceed the value of the characteristics of the foreign samples. Evaluation of the effectiveness and reliability of these systems and of new control algorithms implemented a wireless transmission system, demonstrates the probability of their operation required to ensure the standard level of the individual fire risk. The article discusses an unconventional concept of fire safety of people by improving the reliability and efficiency of functioning of the elements and their governing systems. The principles of this concept should form the basis for the design of fire protection systems of high-rise buildings. Their implementation in conjunction with the organization of a combined phased evacuation (pedestrian evacuation + protected elevator evacuation) will ensure the safety of high-rise buildings and decrease the time of stay of people in these building in emergency situations.

It was proposed to substantiate quantitative solutions in the design and operation of safety systems of autonomous objects on the basis of methods of the theory of queuing systems. The article deals with the problems of analysis and synthesis of the queuing systems when solving the problems of ensuring the safety of objects (for example, fire-fighting or emergency protection systems of an autonomous remote object), which feature is the availability of different types of applications that require different maintenance time (for example, fire and rescue units or repair and recovery teams). While solving problems of analysis the probability p of finding the system in key states determines. S₀ - there were no problematic situations, all the service channels are free; S_u - at least one service channel is available, capable of responding to the problem (service request); S_ref - all n service channels are busy, there is no possibility to react to the problem that has arisen (the application receives a denial of service). While solving the synthesis problem, the necessary quantitative characteristics of the system, such as the number of service channels n , the number of queues and the speed of service {λ}, are selected from the given permissible values of probabilities p₀, p_u and p_ref and known frequencies {μ}. Step by step systems are considered with applications of two types - one-channel and two-channel applications and a system with applications of three types - one-channel, two-channel and three-channel applications. Graphs and equations describing the states of the system and analytical solutions for finding the probabilities of the ground states are given for each of the considered types of systems. Universal expressions are obtained for finding the probabilities of key states for an n -channel queuing system without a queue under standard assumptions for m type applications. The justification of the obtained expressions is given. Examples of characteristics calculation for one-channel, two-channel and three-channel queuing systems with two and three types of applications are given. In particular, the probability of finding a system in a state when no applications are received ( p₀) is calculated, when the requests arrive and one service channel ( p_u ) is left and when all the service channels are occupied ( p_ref ). Examples of solving problems of analysis and synthesis are given for each of the considered types of systems. The article clearly demonstrates the possibility of applying the above methods to the problems of creating integrated security systems for remote autonomous objects, in particular, located in the Far North and in the Arctic zone. This work is a logical continuation of the article Tarantsev A. A., Kholostov A. L., Ishchenko A. D., Potapenko V. V. Problems of analysis and synthesis of application service systems of several types. Pozharovzryvobezopasnost / Fire and Explosion Safety , 2017, vol. 26, no. 3, pp. 31-38.

This work contains the review of the literature about influence of frequency rate of foam on effectiveness of fire extinguishing. It is known that the frequency rate of foam significantly influences key parameters of fire extinguishing. Foam generators do not allow to maintain up-to-the-mark frequency rate of foam with changing pressure. As a result the frequency rate changes during time of its giving, and for its monitoring when carrying out tests it requires the device which is capable to measure frequency rate in real time. Some ways of determination of frequency rate of foam in laboratory, and in the conditions of carrying out actual tests are analysed. In the main way is weighted one. Its weak spot consists in inaccuracy of determination of values of frequency rate of foam. At suppression with ready foam in laboratory a key indicator is its stability. During actual tests with application of high-head foam generators the essential error arises because of air barbotage. Earlier methods of determination of frequency rate on a direct-current conductivity of foam were used. However, despite accuracy of these methods, they did not find application in the standardized techniques. Common weak spot of the existing ways of determination of frequency rate of foam is that they do not consider a counter pressure in system which arises at sublayer fire extinguishing. The purpose of this work - to offer the device, which is able to measured of frequency rate of foam at sublayer fire extinguishing uninterrupted, throughout all time of giving. There were two steps of researches. At the first stage the calibration cell was used. The dependence of coefficient of a cell on resistance between electrodes is established, using an aqueous solution of chloride of a potassium with the known direct-current conductivity was fixed. Then the specific resistance of working solution of the fluorinated film-forming foamer was defined. At the second stage a set-up which allowed to reveal dependence of frequency rate of foam on the size of the relation of a direct-current conductivity of foam to a direct-current conductivity of working solution was piked up. As a result of the conducted researches the mathematical dependence allowing to determine values of frequency rate of foam by the relation of a direct-current conductivity of foam to a direct-current conductivity of working solution was offered. The constant of proportionality for determination of low frequency rate of foam is established. The technique allowing to define frequency rate of the given foam at sublayer fire extinguishing is offered, throughout all time of giving taking into account a counterpressure at the exit of a high-head foam generator.