Room Fire Research Articles

Risk-informed Emergency Response Training for Backdraft in Nuclear Power Plants

Research has been conducted for developing fire evacuation and response training programs for nuclear power plant (NPP) application. Among numerous fire scenarios that may occur in an NPP environment, three different points of origin for a fire were selected for the program based on a risk-informed approach: switchgear room, main control room, and safety injection pump room. Fire outcomes were predicted for these scenarios via numerical modeling and the results were incorporated into the newly developed fire evacuation and response training program for the APR1400, Korea’s next-generation NPP model. The switchgear room fire scenario was found to have the most potential for backdraft to occur during manual fire response following automatic gaseous fire suppression system activation. The emergency response manual does discuss this possible backdraft occurrence; however, the guidance to avoid injuries is qualitative, such as to be cautious of backdrafts and wait a sufficient amount of time after opening a door before entering the. In this study, backdraft phenomenon that may occur from a switchgear room fire was numerically examined using the recent version of the Fire Dynamics Simulator to develop an appropriate timeline to be implemented in the fire evacuation and response training program. Based on the findings, the following guidance is provided: (1) backdraft can only occur when the fire originates in the space near the door; (2) wait at least 10 minutes after opening the door before entering the room; (3) watch for rapid smoke production, as this may be an antecedent phenomenon of backdraft; and (4) when smoke production increases rapidly, leave the room as soon as possible to avoid being caught within the deflagrating flames from a backdraft.

Effects of hydrogen isotope type on oxidation rates for trace releases

The fraction of tritium converted to the water form in a fire scenario is one of the metrics of greatest interest for radiological safety assessments. The conversion fraction is one of the prime variables contributing to the hazard assessment. This paper presents measurements of oxidation rates for the non-radioactive hydrogen isotopes (protium and deuterium) at sub-flammable concentrations that are typical of many of the most likely tritium release scenarios. These measurements are fit to a simplified 1-step kinetic rate expression, and the isotopic trends for protium and deuterium are extrapolated to produce a model appropriate for tritium. The effects of the new kinetic models are evaluated via CFD simulations of an ISO-9705 standard room fire that includes a trace release of hydrogen isotope (tritium), illustrating the high importance of the correct (measurement-based) kinetics to the outcome of the simulated conversion.

Self‐Powered Fire Alarm System with Layer‐by‐layer Graphene Oxide/Chitosan Nanocoating of Flame‐Retardant Nanofilms

This study develops a self‐powered fire alarm system that utilizes a sandwich‐like self‐powered fire sensor (SSFS) with a simple system to prevent room fires. The SSFS is small, flame‐retardant, and can be easily installed on furniture or doors. The SSFS uses a nanogenerator constructed by poly(vinylidenefluoride‐co‐trifluoroethylene) (PVDF‐TrFE) nanofibers and a flexible printed circuit board (FPCB) to produce electrical power by harvesting motion energy. This nanogenerator can fully charge capacitors in a few minutes and produces a maximum voltage output of 6.47 V. The SSFS also features two flame‐retardant melamine foams (MFs) coated with graphene oxide (GO) and a chitosan multilayer nanocoating that is fabricated by layer‐by‐layer technology (LBL technology). While encountering a high‐temperature situation, the electrical state of MFs changes from insulated to conductive, triggering the fire alarm light in about four seconds. The sandwich‐like design allows the SSFS to respond to a variety of fire alarm situations, especially in the case where both the top and bottom of the fire alarm sensor are exposed to flame (bilateral fire burning). It is such an innovative research to decrease the delay time of fire‐warning by using this sandwich‐like design fire sensor. The nanogenerator can keep the warning working for 22 s after the initial trigger, which produces enough time to ensure people stay clear of the fire source. All in all, this study presents a novel approach to reducing the risk of building fires through a lightweight and self‐powered fire alarm system that harvests motion energy using piezoelectric nanogenerators (PENGs).

A Feasibility Study on Translation of RGB Images to Thermal Images: Development of a Machine Learning Algorithm

The thermal image is an important source of data in the fire safety research area, as it provides temperature information at pixel-level of a region. The combination of temperature value together with precise location information from thermal image coordinates enables a comprehensive and quantitative analysis of the combustion phenomenon of fire. However, it is not always easy to capture and save suitable thermal images for analysis due to several limitations, such as personnel load, hardware capability, and operating requirements. Therefore, it is necessary to have a substitution solution when thermal images cannot be captured in time. Inspired by the success of previous empirical and theoretical study of deep neural networks from deep learning on image-to-image translation tasks, this paper presents a feasibility study on translating RGB vision images to thermal images by a brand-new model of deep neural network. It is called dual-attention generative adversarial network (DAGAN). DAGAN features attention mechanisms proposed by us, which include both foreground and background attention, to improve the output quality for translation to thermal images. DAGAN was trained and validated by image data from fire tests with a different setup, including room fire tests, single item burning tests and open fire tests. Our investigation is based on qualitative and quantitative results that show that the proposed model is consistently superior to other existing image-to-image translation models on both thermal image patterns quality and pixel-level temperature accuracy, which is close to temperature data extracted from native thermal images. Moreover, the results of the feasibility study also demonstrate that the model could be further developed to assist in the analytics and estimation of more complicated flame and fire scenes based only on RGB vision images.

Flammability of Ocular Surface Lubricants.

Surgical fires pose a substantial risk to patients and can cause significant injury, especially in oculofacial surgery. Ocular surface lubricants can potentially act as fuel for an operating room fire. We present an experimental analysis of the flammability of 9 commonly used ophthalmic lubricants under 4 ignition sources used in oculofacial surgery with and without supplemental oxygen. The flammability of 9 ophthalmic lubricants were tested under various operating room conditions. Each lubricant was exposed to 4 different ignition sources: an open flame lighter, monopolar cautery, bipolar cautery, and hand-held high temperature cautery, and the response of the lubricant was recorded. The testing was conducted both in room air and with 6 L/minute of 100% oxygen directed at the lubricant through a nasal cannula. Any reaction in which there was ignition, sparking, smoking, or a transient or permanent change in appearance of the lubricant was deemed notable. Of the 9 lubricants tested, 4 displayed a reaction to the ignition source. Without supplemental oxygen, 100% petrolatum and neomycin-polysporin-bacitracin-hydrocortisone ointment produced some smoke when applied with the high temperature cautery. Notably, under both the conditions of no supplemental oxygen and with the addition of 6 L/minute of 100% oxygen, the carboxymethylcellulose drops and lidocaine jelly both conducted and sparked with the monopolar cautery leaving visible burn marks on the paper. The overall fire hazard posed by ocular surface lubricants is low. Some topical lubricants can conduct electricity from monopolar cautery, which could increase the risk of inadvertent electrical burns. Certain lubricants could potentially become a fuel source when used in combination with hand-held high temperature battery cautery. Bipolar cautery was not associated with either increased conductivity or flammability with any of the lubricants tested.

Airway fires in otolaryngologic surgery: A database review

PurposeAn estimated 34 % of reported operating room fires involve the airway. Despite the inherent risks in otolaryngologic surgery, education regarding prevention and management of airway fires is limited in graduate medical training. One contributing factor is a lack of reporting of such rare events in our literature. MethodsThe U.S. Food and Drug Administration's Manufacturer and User Facility Device Experience database was queried for reports of adverse events related to fires occurring during surgical procedures of the airway from January 1, 2010, to March 31, 2020. Results3687 reports were identified and 49 unique reports of airway fire were included. Sustained fires were described in 16 (32.7 %) reports and 33 (67.3 %) described transient flares. 2 fires extended beyond the airway and 9 (18.4 %) were noted to have occurred at the start of the case. Fires were reported most commonly during tonsillectomy (n = 22 [44.9 %]), vocal fold excision (n = 5 [10.2 %]), and adenoidectomy (n = 4 [8.2 %]). 46 reports attributed flare initiation to a specific element of the fire triangle. 16 patient and 2 operator injuries were reported. Saline washing was utilized in 7 (14.3 %) cases overall. Patients were extubated immediately in 2 (12.5 %) of the 16 reports of sustained fires. 0 mortalities were reported. ConclusionAirway fires were reported in a variety of upper airway procedures performed regularly by otolaryngologists. The triggering factor that led to fire was identified as a spark or char in about half of the reported cases, and only 2 reports described immediate removal of the endotracheal tube.

Structural and fire performance of masonry walls with ceramic bricks

Ceramic brick masonry construction systems have long been used in civil construction. Understanding their performance at high temperatures is important, as several fires have occurred in recent years in these types of buildings. Therefore, in this study, the structural performances of 16 ceramic brick masonry walls under typical service and fire loads were experimentally analyzed. Parameters, such as the type of ceramic bricks (non-structural common and structural with horizontal and vertical perforations, respectively), the type of test (at room temperature and fire resistance test), load level, and laying mortar were tested. Walls with structural ceramic bricks exhibited low resistance capacities under ambient conditions, which were below normative values and close to practical service load levels. In the event of a fire, the walls constructed with common brick exhibited low fire resistance (FR), not reaching the 30-min class. Structural ceramic brick walls exhibited better fire performance, reaching the 150-min class, but higher loads considerably reduced this time.

Effects of ventilation system design on flame behavior and smoke characteristics for mitigating marine engine room fire hazards

Engine room fires are one of the most harmful types of ship fires, the development of which is closely related to the design of marine ventilation system. In this paper, a full-scale numerical study of ship's engine room fire is carried out using a fire dynamics simulator, and the effects of vent layout and air velocity on the flame behavior, smoke stratification and diffusion are investigated. The three-dimensional model of the engine room is built based on the ocean-going training ship Yukun of Dalian Maritime University. First, the variations of flame behavior under different air vent layouts and wind speeds are explored, and a mathematical model is derived to quantify the flame deflection angle. Then, the effects of ventilation conditions on the smoke stratification in the cabin are analyzed, and the characteristics of hot smoke diffusion are revealed. The results show that a higher ventilation velocity is beneficial to the rapid cooling of the ship's engine room, and the symmetric ventilation layout of Method 3 with a central intake on the upper side and a bottom exhaust on both sides is more conducive to the safety of the engine and other heat source equipment in a fire. This study provides references to the design and optimization of ventilation systems on ships, which can improve the safety of the important equipment in the engine room and prevent further expansion of fire.

IMPROVED REAL-TIME HOUSE FIRE DETECTION SYSTEM PERFORMANCE WITH IMAGE CLASSIFICATION USING MOBILENETV2 MODEL

The problem with the Ardunio microcontroller-based fire detection system with fire and smoke sensors is the detection distance. For example, in another research, it was stated that the maximum distance for fire detection on two pieces of paper that were burned was 140 cm. This means that if the fire point is at a farther distance, the system cannot detect a fire early, of course, this will be problematic if used in a wider room. Based on these problems, a system is needed that can detect fires in large rooms. A method that can be used is detection using image classification. MobileNetV2 is a real-time model for classifying or detecting an object in an image. In this study, the model was built using real-time based on the TensorFlow and Keras libraries. The system will use a laptop with an Nvidia GeForce MX130 GPU, a 48MP resolution smartphone camera, and the OpenCV library for the image classification process, as well as Telegram for sending fire notifications via the Re-quests library. The test results obtained on burnt 80/90 motorcycle tires, the most optimal detection distance is 7 meters with an accuracy of 99.91%. While testing on two sheets of paper that are burned, the most optimal detection distance is 3 meters with an accuracy of 99.75%. The average response time obtained varies greatly from 74.5 ms to 117.1 ms, which depends on the internet network connection.

Upward Fire Spread Hazard of Vertical Greenery Systems: A Comparative Study with External Thermal Insulation Composite System and Double-Skin Façade

Recent studies have shown that vertical greenery systems (VGS) carry a significant fire threat when not properly looked after. Building on this, the fire hazard of VGS was compared to two other thermally efficient building façade systems (TEBFS), namely external thermal insulation composite systems (ETICS) and double-skin façade (DSF). Numerical simulations were conducted in the fire dynamic simulator (FDS). A fire initiated as a room fire of 1 MW followed by a window-ejected flame on a 12 m tall and 9 m wide front façade with a TEBFS. Three scenarios for each TEBFS were simulated for better comparison. Rapid upward fire spread (UFS) was observed in the VGS scenarios, recording average UFS rates of 8.97, 5.51 and 2.86 cms−1 compared to the scenarios of the other 2 TEBFS where the flame failed to reach the top of the façade within the stipulated simulation time of 300 s. The maximum temperatures reached along the façade in VGS scenarios were much higher than those in the other two TEBFS. In conclusion, the fire hazard of VGS in certain conditions is much higher compared to the fire scenarios of ETICS and DSF that are scrutinised by building codes in many countries for fire safety.

Influence of Firefighting Intervention on Fire Spread Characteristics in Ship Engine Room

The purpose of this paper is to investigate and evaluate the ship engine room fire spreading characteristics based on the effect of firefighting interventions. The large eddy simulation (LES) and theoretical models are employed to simulate a fire scene in the engine room. The fire spreading characteristics and the mechanism of the use of a fine water mist are obtained by varying the ventilation conditions and parameters of the water sprinkler. The results show that the reason why a pool fire can be more easily extinguished as the spray speed increases is because the water mist with a higher spray speed has a larger spray area. Meanwhile, the temperature in the engine room would drop more rapidly with the increasing spray area due to the higher evaporation rate. Furthermore, the arrangement of the ventilation conditions had an obvious effect on the fire spreading characteristics, as the depletion of the combustion medium affects the combustion situation.

Spotlight on Operating Room Fires

Biomedical Safety & Standards 53(7):p 49-51, April 15, 2023. | DOI: 10.1097/01.BMSAS.0000924568.48143.c2

Numerical Simulations of Gas Burner Experiments in a Residential Structure with HVAC System

Controlled fire experiments using a gas burner were previously conducted in a purpose-built, two-story, moderately air-tight residential structure to understand the effect of a heating, ventilating, and air conditioning (HVAC) system and door positions on the fire-induced environment. Temperatures, gas concentrations (oxygen, water vapor, carbon dioxide), and differential pressures were monitored throughout the structure. HVAC status (off vs. on) and stairwell door position of the fire room (open vs. closed) were varied for the experiments analyzed in this paper. In this study, Fire Dynamics Simulator (FDS) v. 6.7.9 was used to simulate these experiments. Experimental data quantifying the air tightness of the building and cold flowrates through HVAC vents were determined to be important to optimize leakages and HVAC loss coefficients for the simulation setup. Pressure development in the structure was predicted correctly to be higher on the first floor and lower in the basement, but the magnitude of steady-state pressure was underpredicted. The measured and predicted steady-state temperature distributions were statistically different for the cases with and without the HVAC on, regardless of the door position. FDS predicted gas transport through the HVAC duct network, and under-predicted temperature rise and water vapor content by about 9% and 10%, respectively, and over-predicted volumetric oxygen and carbon dioxide content by about 21% and 6%, respectively. Temperature rise prediction in the closed room, where the gas transport primarily occurred via the HVAC duct network, improved after including heat loss from the HVAC duct to the ambient.

Simulation Test on Cooling and Fire Suppression with Liquid Nitrogen in Computer Room of Data Center

With the rapid development of worldwide computer data center construction, the reliability requirements of the fire-fighting system for data center rooms are also increasing. By using the self-designed simulation platform of liquid nitrogen spray, this paper studies the liquid nitrogen cooling process in the initial heating stage of a computer data center room fire and the liquid nitrogen extinguishing effects for common combustible materials, revealing the feasibility of applying liquid nitrogen to the fire extinguishing system for data center room. The results show that the cooling and inerting effects with quarter sector fan-shaped 6520 spray nozzle are the best among seven types of spray nozzles, the relative temperature changes by more than 50% within 5 min, and the oxygen concentration in the test space drops below 10%. Compared with optical fiber, the ignition range of uninterruptible power supply com-bination during combustion is relatively small. Liquid nitrogen has a significant fire-extinguishing effect on two combustible materials, which can successfully extinguish optical fiber and UPS within 3 min and 2 min, respectively.

Two real room fire and the evaluation of its consequences in terms of fire safety

In this study, 1/1 scale Fire Experiment Laboratory was built to demonstrate the reality of fire with a real fire. In the prepared building, there are 2 fire test rooms measuring 300 × 350cm and 1 observation room measuring 190 × 620cm. In the fire tests, a living room and a bedroom were furnished by calculating the required fire loads. In the fire load calculation, a fire index value of 1.18 was obtained in the bedroom and a fire index value of 1.86 was obtained in the living room. Instant temperature values were taken for each second in the lower, middle and top zones of the fire rooms. The bedroom reached maximum temperatures around 1200 °C in the top zone, 800 °C in the middle zone and 400 °C in the lower zone. And in the living room, maximum temperatures were measured at around 900 °C in the top zone, 600 °C in the middle zone and 300 °C in the lower zone. Moreover, temperature changes outside the building were also recorded. According to the thermal camera images measured, the external wall temperature of the bedroom is around 25–31 °C at maximum temperature and the external wall temperature of the living room is around 41–46 °C at maximum temperature.

Numerical Study on the Flow Coefficient Considering Inclined Space in the Opening between the Fire Room and Inclined Space

In this study, a calculation model was constructed assuming the space from the fire room (basement floor) of the building to the ground floor through an inclined space. The effect of the inclination angle on the flow coefficient in the opening between the fire room and inclined space was investigated. The results showed that the flow coefficient at the opening was maximum around the angles of 20° – 30° and then decreased. In addition, it was confirmed that Equation (8) expressed the relationship between the flow coefficient and inclination angle.

Study on the Setting Method of CFAST to Predict Heat and Smoke Spread

Fire risks may be underestimated when ASET and RSET are individually derived and compared in the performance-based design of a building. Accordingly, the need for the real-time coupling of fire and evacuation simulations has emerged. Therefore, in this study, the predictive performance of CFAST, which requires relatively low computational cost and expertise, was verified as an alternative to FDS, which has limitations in coupling with evacuation simulation because of its high computational cost and expertise. Specifically, the prediction performance of the heat and smoke diffusion behavior was verified by comparing the CFAST prediction results according to the division method of the corridor connected to the fire room with the FDS. The results confirmed that CFAST yielded appropriate results within the model uncertainty range of the FDS for the upper-floor temperature and smoke detector operation time when the corridor was divided into intervals equal to the width. Simultaneously, owing to the limitations of the numerical model for the flow velocity of the ceiling jet, it was confirmed that considerable attention is required to predict the operation time of the heat detector using CFAST.

Моделирование пожаротушения машинного зала газокомпрессорной станции температурно-активированной водой

Purpose. Theoretical studies stated that one of the ways to increase the extinguishing efficiency of temperature-activated water (TAW) is the introduction of water-soluble inhibitory compounds into it. However, simulation of total flooding of confined volumes fires by this medium and field experiments confirming the theoretical conclusions were not carried out. The aim of the work was the experimental study of total flooding of fires in gas compressor stations engine rooms with the introduction of inhibitory salts. To realize it, the following tasks were solved: 1) analysis of existing models of total flooding of fires and the formation of a TAW model in the PyroSim hardware and software complex; 2) carrying out mathematical simulation of total flooding of fires with TAW. Methods. Methods of analysis and synthesis were used to evaluate the available data. To study total flooding processes, the theory of branched-chain combustion processes was used. The objectivity of the found theoretical dependencies was confirmed by the experimental method. Findings. The experimental study allowed us to confirm the objectivity of the theoretical dependencies found. The most effective distribution of the polydisperse droplet phase of TAW was determined to create inhibitory properties. Temperature reduction dependences in a confined volume on the quenching time were determined. Research application field. The obtained models can be used to increase the efficiency of suppressing flame combustion in a confined volume. Conclusions. The obtained results will form the theoretical basis for describing the mechanisms of total flooding with TAW.

노인요양시설의 화재 발생 시 연기 유동장과 단위면적에 따른 피난특성에 관한 연구

The analysis of the flow field in the elderly care facility showed that a vertical flow occurred due to vortex and buoyancy near the airflow entrance and fire source on the floor plan. The velocity in the corridor was high due to the location of the smoke window on the floor plan, and the carbon monoxide mass fraction in the fire room was 0.5 or more within 1 minute. In addition, smoke detectors work much faster than heat detectors, but not many places voluntarily install smoke detectors for economic reasons. Therefore, fire safety standards should be revised to the following to reduce damage in elderly nursing facilities: “Smoke detectors must be installed in living rooms and other rooms (treatment rooms or office rooms) used for purposes such as sleeping, lodging, hospitalization for the elderly.”BR The study of evacuation behavior of occupants of elderly care facilities in unit area showed that evacuation was completed in 4 minutes and 43 seconds in small and medium-sized buildings and in 5 minutes and 5 seconds in large buildings. Considering that the initial evacuation started after about 100 seconds, this results in a difference of about 20 seconds for horizontal evacuation, not considering evacuation over several floors. In addition, a comparison with normal populations in large buildings confirmed that the risk exposure time increased sharply with increasing building size, with the elderly taking 1.7 times longer.

Examination of effects of indoor fires on building structures and people

The scientific study of the harmful effects of indoor fires on building structures and on the environment is a top issue today. Indoor fires frequently occur all over the world. The goal of our research is to examine the effects of an average room fire on the survival possibility of a trapped person and on the building structure, taking into account features of the Eastern European architecture. First, a computational fluid dynamics (CFD) simulation was performed to examine the change of temperature, oxygen, and carbon monoxide concentration in a selected room in a vacant building used for military training. Based on the results, a 1:1 scale fire experiment was carried out with the parameters used in the simulation. The experiment was repeated once with the same settings. It was observed that without the intervention of firefighters, the temperature in the experiment could have rapidly reached 400 °C, as suggested by the simulation, which could have caused structural damage to the building. Furthermore, after 3 min the carbon monoxide concentration reached 400 ppm in both experiments and the simulation, which is a harmful level to people trapped inside the room. Also, in the experiment there was sufficient oxygen at the ground level with what people can survive 3 min.