ignition source
Recently Published Documents


TOTAL DOCUMENTS

127
(FIVE YEARS 33)

H-INDEX

12
(FIVE YEARS 2)

2022 ◽  
Vol 6 (4) ◽  
pp. 363-368
Author(s):  
Yu. S. Kozlova

Emergency modes (short circuits) in electric power system and equipment are the main technical cause of fires. However, it is not always possible to prove the involvement of a particular operating mode in a fire. The fire hazard can be due to three components: a fuel load, an oxidizer and an ignition source. Since overhead transmission lines are used in an open space, they are oxidized. The presence of a fuel load is confirmed by a fire. The source of ignition should be identified. The aim of the study is to develop an algorithm for assessing the fire hazard for short circuits in overhead transmission lines with 1000 V. The study was conducted using scientific analysis, physical experiment and simulation. The ignition source is due to the appearance of an energy source with parameters sufficient to ignite a fuel load. The probability of ignition in overhead line wires depends on the probability of occurrence of the short circuit itself  ( Qi (v1) ) , the probability of failure of protection devices  ( Qi (v2) ), and the probability that the electric current value in the event of a fault is in the range of fire hazard values (Qi(z)). The values of the first two components are determined on the basis of statistical data, taking into account the theory of reliability. The third component is based on the experiment results. The experimental studies made it possible to establish the ranges of fire hazard values for uninsulated aluminum wires of various cross-sections, thereby providing the possibility of calculating ( Qi (z). Using the data obtained and information about the nature of changes in short-circuit currents and performance characteristics of protection devices, depending on the line length, an algorithm for assessing the fire hazard for a short circuit was developed. The results make it possible to assess the fire hazard for short circuits in various sections of the electrical network, made by overhead transmission lines, and to establish the involvement of sparks generated by short circuits in a fire


2022 ◽  
Vol 354 ◽  
pp. 00046
Author(s):  
Gabriela Pupăzan ◽  
Cosmin Colda ◽  
Tiberiu Csaszar ◽  
Adriana Andriș ◽  
Dănuț Grecea

Explosive atmospheres can be caused by gases, vapours, mists, dust, lint or fibres of flammable substance. If enough substance and air are mixed, the imminence of an explosion depends on probability and efficiency of the ignition source. Hazardous areas classified in sectors must be protected from ignition sources. Equipment and protective systems intended for use in potentially explosive atmospheres should be selected to meet the appropriate requirements for protective equipment and systems. The current paper aims to identify opportunities for standardization of pressurized equipment. The first part of the paper presents the risk of explosion associated with the presence of flammable substances and protection against explosions. The concept and opportunities of using pressurization are described in the second part of the paper. The third part refers to considerations regarding size and shape of pressurized equipment. A synthesis of pressurized equipment’s offer - dimensions, shape and functional role, is presented in the last part of the paper. Among the conclusions the existence of a gauge profile that depends on purpose, volume, operating position and assembly of the equipment, was mentioned.


2022 ◽  
pp. 85-106
Author(s):  
Aditya Ranjan ◽  
Shweta Chandra ◽  
Rohan Bhalla ◽  
Sumedha Agarwal

Experience economy plays a predominant role in the hospitality industry. Consumer experience has always been of great importance for the hospitality business. As consumer experience evolved, businesses needed and still need to find new ways to differentiate themselves. To remain competitive and stay in the market, hospitality firms are working towards creating outstanding and memorable experiences that exceed guest expectations. In the context of Pine and Gilmore's experience economy conceptual model, the chapter attempts to theorize and explain how hospitality businesses are curating consumer experiential encounters. Digital nomads are the ignition source of driving an experience economy. The chapter further highlights how technology would additionally ease hospitality enterprises to frame excellent strategies focused on supplying the value to the digital consumers and then expecting their customers to generate additional business.


Wood Research ◽  
2021 ◽  
Vol 66 (6) ◽  
pp. 969-980
Author(s):  
VLADIMÍR MÓZER ◽  
PETR HEJTMÁNEK ◽  
DANIELA PITELKOVÁ ◽  
LUCIE HASALOVÁ

This paper presents a series of full-scale tests conducted with office furniture made from OSB boards. Ignition source (30 kW gas burner) position and enclosure effects, free burn vs. ISO 9705 room, were evaluated from the perspective of instantaneous (HRR) and total heat (THR) released by the fuel packages. It was found that both of the evaluated factors have impact primarily on HRR – the peak ranging from 874 kW to 1 154 kW was delayed by approx. 50 to 60 s in the free-burn experiments; the THR remained relatively consistent at approx. 875 ± 30 MJ, meaning that in the observed period very similar amounts of fuel were burned. The thermal feedback within the enclosure seemed to be partially counteracted by the lack of oxygen, resulting in slightly higher HRR in free-burn test following the first peak. The findings of the research are applicable to fire hazard prediction by fire modelling.


2021 ◽  
Vol 30 (5) ◽  
pp. 23-29
Author(s):  
N. L. Poletaev

Introduction. One of the reasons for the overestimation of the explosion hazard of dust inside a (20 ± 2)-liter chamber is the elevated initial temperature of the air suspension. The initial temperature is also raised by the process of filling the pre-emptied chamber with air from the receiver, used to distribute dust over the chamber. In this work, an increase in the air temperature inside an 18.7-liter chamber was identified in an experiment for the case of addition of air from the receiver.The methodology of an experiment. The air temperature in the chamber was measured at the time when the air from the receiver was added using a WR 5/20 thermoelectric converter (a thermocouple). The thermocouple junction was located at the distance of 70 mm from the inner wall of the chamber. The thermocouple signal was processed by an MCLab PRO programmable logic controller (the time resolution is 1 ms).Research results. The measuring instruments recorded an increase in the temperature of the thermocouple junction by +14 degrees. Due to the comparability of the inertia of the thermocouple (3 s) and the characteristic time of air cooling by the chamber walls (5 s), the measurement results underestimated the real value of a jump in the air temperature inside the chamber. Measurement results were refined using a simple model of heat transfer between the objects involved in the process (thermocouple junction – air – chamber wall) that entailed the exponential relaxation of the temperature difference over time. As a result, an estimated increase in the initial temperature inside the chamber of +30 degrees was identified.Results and discussion. The temperature jump by +30 degrees makes a noticeable contribution to the total jump in the initial temperature, which was previously tied solely to the burnout of the ignition source (+80 degrees).Conclusions. Given the known increase in the temperature inside the chamber caused by the burnout ofa standard ignition source (2 kJ), the real value of the initial temperature of the environment can reach 135 °C in the course of studying dust in a (20 ± 2)-liter chamber.


2021 ◽  
Vol 12 (4) ◽  
pp. 162
Author(s):  
Yuxiang Feng ◽  
Jiaolong Cao ◽  
Yufeng Zhang ◽  
Ding Jin

In order to ensure the safety of shore-based hydrogen bunkering operations, this paper takes a 2000-ton bulk hydrogen powered ship as an example. Firstly, the HAZID method is used to identify the hazards of hydrogen bunkering, then the probability of each scenario is analyzed, and then the consequences of scenarios with high risk based on FLACS software is simulated. Finally, the personal risk of bunkering operation is evaluated and the bunkering restriction area is defined. The results show that the personal risk of shore-based bunkering operation of hydrogen powered ship is acceptable, but the following risk control measures should be taken: (1) The bunkering restriction area shall be delineated, and only the necessary operators are allowed to enter the area and control the any form of potential ignition source; (2) The hose is the high risk hazards during bunkering. The design form of bunkering arm and bunkering hose is considered to shorten the length of the hose as far as possible; (3) A safe distance between shore-based hydrogenation station and the building outside the station should be guaranteed. The results have a guiding role in effectively reducing the risk of hydrogen bunkering operation.


PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255572
Author(s):  
Jianlong Zhao ◽  
Yanfeng Li ◽  
Junmei Li ◽  
Youbo Huang ◽  
Jinxiang Wu

In this study, a series of small-scale experiments were conducted to investigate the backdraft phenomenon in a compartment (1.1 × 0.4 × 0.75 m) with woodblocks as fuel. This research focused on the effects of compartment window woodblock areas on backdraft time, with a video recording of the experimental phenomena. Thermocouples and a gas analyzer were used to measure the temperature and the concentration of gas components in the compartment, respectively. There was no additional heat source or ignition source pre-set in the compartment at the beginning of the experiments; the experimental processes only depended on the heat released from the burning or smoldering of woodblocks. When compartment ventilation improved, smoldering of woodblocks became intense, and backdraft occurred. The results show that backdraft time is shorten with increases of compartment window and woodblock areas, and opening the upper window of a compartment could avoid the backdraft phenomenon. The results help to understand the backdraft phenomenon of solid fuel and, more importantly, could help firefighters adopt reasonable fire-fighting strategies for restraining backdraft occurrence.


2021 ◽  
pp. 201010582110310
Author(s):  
Ernest Weisheng Ho ◽  
Eng Leonard ◽  
Lee Tih-Shih ◽  
Gregory James Meredith

Electroconvulsive therapy (ECT) is effective for mood disorders and schizophrenia. Thermal burns, while rare, are potentially sight and life threatening. The three elements necessary for a fire are often in close proximity during a session: an oxidiser (oxygen), an ignition source (faulty electrodes, poor contact with skin producing a spark) and fuel (hair, residual alcohol cleanser). This case report describes one such incident when a patient sustained a burn during ECT, with poor contact of electrode pad with skin, high impedance and an oxygen-rich environment possibly contributing. Given that ECT is conducted relatively frequently (once every 2–3 days) in a usual regimen, we make recommendations for safe application of electrode pads for temporal placement ECT.


2021 ◽  
Vol 35 (3) ◽  
pp. 59-67
Author(s):  
Jung-Hyun Ryu

The fire risk of a nuclear power plant is evaluated using fixed and transient ignition sources. In terms of the overall fire risk, the proportion of transient ignition sources is very small. However, because the uncertainty due to the difference between the assumptions and the modeling method is relatively large, it is necessary to establish a methodology to address this. In this study, the new transient ignition source evaluation method presented in NUREG/CR-6850, the ignition source frequency revised in NUREG-2169, and the input parameters for transient fire modeling presented in NUREG-2233 were used to evaluate the fire risk assessment for transient ignition sources. In this new evaluation methodology, the fire ignition frequency is quantitatively evaluated based on the characteristics of the area, and an area-based scenario evaluation method considering the location of the transient ignition source is proposed for the evaluation within the area. As a result of applying the new methodology to the switchgear room of a reference nuclear power plant, an approximately 70% risk reduction was confirmed compared to the existing EPRI TR-105928 method. In the future, if fire risk assessment for transient ignition sources in nuclear power plants is applied using the results of this study, it is expected that areas whose control is important in the event of a fire can be determined, which should help reduce highly rated fire risks.


2021 ◽  
pp. 27-35
Author(s):  
Геннадий Васильевич Боков ◽  
Антон Александрович Назаров ◽  
Денис Геннадьевич Боков

Приведены результаты исследований монтажных проводов электрических шкафов на воспламеняемость под воздействием тока. Выделены три зоны сверхтока, имеющие отличительные особенности появления источника зажигания. Показано влияние изоляции провода на частоту появления воспламенения в местах присоединения его к элементу электрооборудования. Представлены данные о воспламеняемости поливинилхлоридной изоляции в диапазоне пожароопасных значений сверхтока. Предложено характеризовать электрический провод как потенциальный источник зажигания площадью, образованной зависимостью времени воспламенения изоляции в интервале возможных сверхтоков. Wires are widely used for internal installation of electrical cabinets. Number of fire cases caused by wires takes one of the first places in fire statistics. Application of wires in the cabinets has its own fire-prone aspects peculiarities as concerns initiation of electrical nature ignition source. It appears both at single wire laying and at laying in cords where wires touch each other also in connection points of electrical apparatuses and devices located in the cabinet. The article considers issues of ignition source appearance in wires taking into account specifics of their installation in electrical cabinets. Ignition source appearance in a single wire and in wires contacting each other has a difference. There are given experimental data on inflammation frequency of wire insulation material at single wire laying and also at higher resistance in electrical elements connection points. Zones that differ in characteristic features of wire as an ignition source are given in the range of possible overcurrents. Zone A is characterized by insulation ignition with low probability due to low current density that is not enough to heat the wire up to the critical temperature Т, at which thermal decomposition products of wire insulating polymeric cover ignite. Zone B is designated in the range of overcurrent ratio from 2,5 to 18 compared with the long term permissible current value, in which insulation inflammation is observed due to fast conductor heating taking into account the influence of connection points with devices and apparatuses where increased transient resistance is present. It is experimentally confirmed that with the increase in transient resistance at the point of conductor connection with electrical equipment elements, the inflammation frequency of wire insulation increases. At the same time, the overcurrent range where ignition source appears reduces. It is proposed to use the area limited by the dependence of the time before insulation inflammation from the minimum to the maximum current value at which ignition occurs as a characteristic of the wire as an ignition source.


Sign in / Sign up

Export Citation Format

Share Document