Fire Suppression Performance Research Articles

Predicting sprinkler spray dispersion in FireFOAM

Accurate representation of fire sprinkler spray enables quantitative engineering analysis of fire suppression performance. Increasingly, fire sprinkler systems are evaluated using computer fire models in which sprinkler spray is simulated with Lagrangian particles. However, limited guidance exists as to how to predict the behavior of complex, spatio-stochastic fire sprinkler spray or how to accurately represent the dispersion of spray in terms of Lagrangian particles. The current work predicts the dispersion of the fire sprinkler spray generated by a canonical axisymmetric sprinkler using a Lagrangian particle tracking model within FireFOAM, an open source computational fluid dynamics fire model. In this work, the initial fire sprinkler spray is described with a new spray injection model characterized by a multivariate probability distribution function related to spatially resolved breakup radius, volume flux, drop size, and drop velocity. This function is stochastically sampled to generate Lagrangian particles representative of the near-field spray and the dispersion of these Lagrangian particles is in turn simulated in FireFOAM to predict the far-field spray. Our new model is compared to a baseline FireFOAM spray injection model which incorporated fewer spray details. Modeled results are compared to highly resolved far-field measurements of axisymmetric sprinkler sprays generated by the Spatially-Resolved Spray Scanning System (4S).

Performance Evaluation of Water Mist with Mixed Surfactant Additives based on Absorption Property

Abstract The leaking of hazardous, flammable hydrocarbons, such as methane, possesses potential risk to generate accidents of fire or explosion. The conventional technique is water mist which can reduce the environment concentration of flammable gas and manage accidents of fire caused by hazardous hydrocarbons leaking, but pure water mist extremely restricts its popularization and application due to the poor solubility of hydrocarbons. Therefore, the mixed surfactant is used as water mist additive for its excellent physical and chemical nature, and its performance is investigated and evaluated experimentally. A formula of mixed surfactant additive has been developed and the physicochemical properties of water mist with mixed surfactant additive were measured. Additionally, the present work establishes a series of lab-scale experiments to study absorption capacity and gasoline pool fire suppression performance of water mist with mixed surfactant additives and the effect factors. The concentration transient within the test chamber has been evaluated during the absorption experiment. Results showed that water mist with mixed surfactant additives is shown to be efficient in absorbing methane, especially under the condition of low methane concentrations, water mist with 5% mixed surfactant, absorbing time less than 150s had best absorption capacity. Furthermore, the addition of mixed surfactant in water mist can shorten fire suppression time and restrain fire enhancement effectively at the beginning when extinguishes the oil pool fire. The water mist with mixed surfactant additives will greatly promote the large-scale application of water mist technology used to manage accidents of hazardous hydrocarbons leakage or fire.

Hydroxyl-decorated ammonium polyphosphate as flame retardant reinforcing agent in solvent-free two-component polyurethane

Despite being extensively implemented in research, it remains challenging but highly desirable to develop ammonium polyphosphate (APP)-based polyurethane (PU) combining excellent flame retardancy and improved mechanical properties. Herein, hydroxyl-decorated APP (OH-APP) was successfully fabricated through a facile, green, yet efficient cation exchange reaction with N-methylethanolamine, and utilized as a multifunctional reinforcing agent for solvent-free two-component PU in the curing process. Results demonstrate that the conjugation of OH-APP imparts to the resultant cured PU samples (PU/OH-APP) enhanced fire safety and smoke suppression performance, as evidenced by the considerable decrease in peak heat release rate, total heat release, peak smoke production rate and total smoke production by 75.4, 30.1, 64.3 and 14.4% over those of pure PU. Furthermore, the tensile strength of PU/OH-APP is improved by 66.5%, while the ductility is well maintained, highlighting its promising potential in industrial applications. This work is aimed at opening a new avenue for the development of APP-based PU with outstanding performances through covalent anchoring approaches. © 2017 Society of Chemical Industry

A description of the initial fire sprinkler spray

Accurate representation of the fire sprinkler spray enables quantitative engineering analysis of fire suppression performance. Increasingly, fire sprinkler systems are analyzed with computational fluid dynamics (CFD) fire models where the sprinkler spray is simulated with Lagrangian particles dispersed throughout the fire induced flow. However, there is limited guidance for representing the complex, spatio-stochastic characteristics of the initial sprinkler sprays in terms of these Lagrangian particles. The present work establishes a descriptive analytical framework for the initial sprinkler spray that is rigorously grounded in statistical theory, related to local spray properties, and capable of translating high-fidelity measurements into CFD inputs. This framework describes the initial sprinkler spray as a unified probability distribution function, varying over an initialization surface, and statistically representing measurements of near field local spray properties (volume flux, drop size distribution, and drop size–velocity correlation). Lagrangian particles accurately representing the sprinkler spray may be initialized by a stochastic sampling of this probability distribution function. This novel representation enables high-fidelity initialization of the sprinkler spray in CFD fire models, improving their utility in quantitative engineering analysis.

Preparation of Dry Waters and their Fire Extinguishing Performance

Dry waters with ammonium biphosphate solution as core were prepared and used as fire extinguishing agent for the first time. The dry waters were near-spherical and had a size smaller than 200 μm. The fire suppression performance of the dry waters was higher than that of ABC powder. The dry waters with different core composition could be mixed and used as fire extinguishing agent.

Fabrication of hierarchical zeolite 4A microspheres with improved adsorption capacity to bromofluoropropene and their fire suppression performance

Novel hierarchical zeolite 4A microspheres consisted of interconnected nanoflakes were successfully prepared from Kaolin precursor in a simple ethanol–water mixed solvent system. While in aqueous solution without ethanol, only commonly cubic particles were obtained. It was found that the concentration of ethanol in the solvent was crucial to the production of microspheres. There existed an optimized concentration range of ethanol where microspheres were fabricated with highly yield. Thus-prepared single-phase zeolite 4A microspheres exhibited a large Brunauer–Emmett–Teller (BET) surface area of 666.9m2/g, pore volume of 0.0147cm3/g and average pore size of 6.9nm. The porous spheres exhibited an adsorption capacity of 8.7wt.% to a clean gas fire suppressant of 2-bromo-3,3,3-trifluoropropene (BTP) at room temperature, much higher than that of conventional cubic zeolite 4A particles (4.2wt.%). Bench scale fire tests revealed that these zeolite 4A microspheres soaked with BTP exhibited much better performance than that of cubic counterparts in suppressing methane/air coflowing diffusion flames in cup burner, with the fire extinguishing concentration decreased by more than 20% at the comparable powder discharging rate. Such an improvement could be ascribed to the larger surface area and higher adsorption capacity of zeolite 4A microspheres.

Experimental research on the water mist fire suppression performance in an enclosed space by changing the characteristics of nozzles

Water mist is an ideal way in enclosed spaces, where fire suppression efficiency is very important due to limited water and water damage to equipment. The purpose of this paper is to find a more effective way of fire suppression performance by changing characteristics of nozzles, taking into account extinguishing time, water consumption, toxic gas concentration, temperature decay and cover area. Two groups of pressure-swirl nozzles with the same flow rate and different spray cone angles were employed. The angle was adjusted by changing diameters and lengths of entrance, swirl chamber and orifice of nozzle. It was found that the cover area and the droplet size increased slightly with the spray angle. The fire tests results showed that the extinguishing time increased with the spray cone angle, and increased with the flow rate and the operating pressure decreasing. The temperature decay rate was improved by decreasing the angle or increasing the flow rate. In addition, with an increase in the extinguishing time, the concentration of O2 decreased while the CO and CO2 increased. However, the gas concentrations were not affected by the water mist discharge duration if it exceeded the extinguishing time. For a specific region and a certain amount of water, the performance can be improved by the approach: increasing the flow rate and the spray angle simultaneously and decreasing the discharge duration. The authors suggest setting proper flow rate and spray cone angle which match mutually, in order to maximize the utilization of water.

Experimental and Numerical Study of Fire Suppression Performance of Ultral-Fine Water Mist in a Confined Space

Abstract Ultra-fine water mist (UFM) is a clean agent with a gas like property. Fire suppression experiemt was conducted in a confined space. Numerical simulation using DPM model and dense gas model were carried out to compare with experiment. Simulaition discovered that dense gas model is more suitable for predicting UFM transportation and flow behavior compared with DPM model. Both experiment and simulation found that fire of a larger size is easier to extinguish in a compartment space, which is because fire sources can promote transportation of UFM in a compartment. Fire location also affects the fire suppression performance by promoting or suppressing the transportation of UFM.

Experimental Study on Fire Extinguishing of Water Mist with a Newly Prepared Multi-component Additive

In order to enhance the fire suppression performance of water mist, a new multi-component additive of water mist is produced through physics process for the typical fire (oil pool fires and wood crib fires). To study the effectiveness of the water mist adding this new multi- component additive in fire suppression, a laboratory-scale suppression system was built and a series of tests were conducted in this system. The experimental result reveals that the fire suppression effectiveness of water mist is improved greatly by adding the multi-component additives, Along with increasing the amount of multi-component additives, the fire suppression time of oil pool fire drops rapidly, then increases slightly at some points; but the time of wood crib fire declines gently, then tends to become stable. Finally, the suppression mechanism is discussed so as to find out the deep relationship between the multi-component additive and suppression effectiveness.

Experimental evaluation of fire suppression characteristics of twin fluid water mist system

This paper reports the results of experiments performed in a 1m3 chamber on suppression of n-heptane pool fires using fine water-mist (DV50∼23μm) generated from air aspirating twin fluid nozzles in continuous and pulsed mode. The effect of pulsing duration (1.0–1.4s ON/0–1.3s OFF), fire size (5–12.5kW) and pre-burn duration (10–30s) was studied for air and nitrogen as the atomizing fluid. During these experiments, fire suppression time, quantity of water for suppression and temperatures in the chamber were recorded. Fire suppression performance index (FSPI) was developed as an indicative measure of fire suppression effectiveness. It was observed that the best FSPI was achieved for a pulsing cycle of 1.3s ON and 1s OFF. Nitrogen as atomizing medium for mist generation was found to be more effective for fire suppression by 30–50%. Increase in pre-burn duration and fire size was found to reduce suppression time due to larger heat available in the chamber. Fire suppression for larger fire size was achieved with 25–30% of the combustion heat absorbed by the mist, indicating important contribution to fire suppression by other processes such as oxygen dilution and inerting due to water vapour.

Full-scale experimental study on fire suppression performance of a designed water mist system for rescue station of long railway tunnel

Rescue stations have been newly designed in some super-long mountain railway tunnels of China such as over 30 km long, as a new type of strategic counteract design for fire accident in tunnels. Water mist fire suppression systems are needed to be installed in such rescue stations to control the train fire. However, there is no design engineering experience for it. In this article, a full-scale experimental facility was built to study the fire suppression performance of water mist system in such railway tunnel rescue station. A series of full-scale tests was preliminarily conducted considering the fire position was on top of, inside, and under the train carriage with gasoline pool fire and wood crib fire used as fire sources. A design of water mist suppression system for such a fire scenario was presented, and its performance was tested. Experimental data on temperature, CO concentration, and radiation flux were collected and analyzed. The results showed that the water mist system could control fires, cool the air temperature in the rescue station, and strongly reduce the radiant heat flux in the vicinity of the fire source under various ventilation conditions. However, the visibility of the rescue station was much deteriorated after the injection of water mist, so that emergency lights and evacuation lights are necessary for personnel evacuation. The changes of fire extinguishing time with longitudinal ventilation velocities showed that longitudinal ventilation could provide both favorable and unfavorable conditions for water mist fire extinguishment. So, to achieve efficient fire suppression performance of water mist system, attention might be paid to the controls of tunnel ventilation system in the event of a fire in a railway tunnel rescue station. The design of the water mist system and the full-scale experimental data on the fire suppression performance presented in this article may serve as a reference for such engineering applications.

Assessment of Physical Fitness Aspects and Their Relationship to Firefighters' Job Abilities

The purpose of this study was to identify the relationships between various fitness parameters and firefighting performance on an "Ability Test" (AT) that included a set of 6 simulated firefighting tasks. The relationships between each fitness parameter and each task of the AT were determined. Ninety firefighters participated in this study (age 33 ± 7 years). The AT completion time was associated with abdominal strength (r = -0.53, p < 0.01), relative power (r = -0.44, p < 0.01), upper-body muscular endurance (push-ups, r = -0.27, p < 0.05) (sit-ups, r = -0.41, p < 0.01), and upper-body strength (1 repetition maximum bench press, r = -0.41, p < 0.01). In addition, poor performance on the AT was associated with high resting heart rate (r = 0.36, p < 0.01), high body mass index (r = 0.34, p < 0.01), high body fat (BF)% (r = 0.57, p < 0.01), increasing age (r = 0.42, p < 0.01), and large waist size (r = 0.67, p < 0.01). Multiple regression analyses indicated that a significant (F[5, 53] = 14.02, p < 0.01) proportion (60%) of the variation observed in the AT was explained by the variation of the fitness parameters used in the model. This study demonstrated that fitness variables, such as abdominal strength, power (step test), push-ups, resting Hr, and BF%, contributed significantly to the predictive power of firefighters' AT performance. The findings of this study may be useful to fire department instructors and trainers in the design and implementation of training programs that are more specifically tailored to improving both individual firefighting skills and general fire suppression performance.

Early Suppression of Rack Storage Fires with K363 Standard Response Sprinkler

A series of five large-scale fire tests has been conducted to evaluate the fire suppression performance of a standard-response large K-factor pendent sprinkler for protection of rack storages of Standard Plastic Commodity under a 9.1 or 12.2 m high ceiling. The sprinkler has a nominal 25.4 mm orifice diameter and a nominal 363 L/min/(bar)1/2 discharge coefficient (K-factor). The activation mechanism is a standard-response solder link, rated at 72°C, with a Response Time Index (RTI) of 130(m-s) 1/2. The sprinkler spacing was maintained at 3 m by 3 m and the deflector to ceiling distance was 343 mm. Test variables included sprinkler discharge pressure, storage height, ceiling clearance and ignition location. Two fire scenarios were used to evaluate the fire suppression performance of the sprinkler: 1) a fire between two sprinklers with low ceiling clearance (1.8 m) to evaluate sprinkler spray overlapping ability; 2) a fire underneath a sprinkler with large ceiling clearance (3.4 m) to evaluate sprinkler spray penetration ability against the fire plume. For 12.2 m ceiling height, the sprinkler at a discharge pressure of 0.21 MPa and a sprinkler discharge rate of 522 L/min achieved fire suppression for both the two fire scenarios. For the 9.1 m ceiling height, the sprinkler at a discharge pressure of 0.07 MPa with a discharge rate of 302 L/min or at a discharge pressure of 0.10 MPa with a discharge rate of 369 L/min provided fire suppression performance for the first scenario. For the second fire scenario under a 9.1 m high ceiling, the sprinkler at a discharge pressure of 0.07 MPa with a discharge rate of 302 L/min only achieved fire control. Actual Delivered Densities (ADD) of the sprinkler for some of the test conditions employed in the large-scale fire tests were measured. The large water drops generated from the large K factor (K363) sprinkler enhance its penetration ability against the fire plume. The ADD data confirm that as ADD greater than Required Delivered Density (RDD) for fire suppression, suppression of the fire can be expected. The results of the five fire tests show that a standard-response K363 sprinkler can be as effective as ESFR sprinklers in providing protection for storages in warehouses with ceiling height up to 12.2 m.

Experimental Study on the Effects of Low Ambient Pressure Conditions at High Altitude on Fire Suppression with Water Mist

In order to study the effects of low ambient pressure conditions at high altitude on fire suppression with water mist, a water mist fire suppression experimental facility was built in Lhasa, Tibet, a province of China. Using this facility, water mist extinguishing tests were carried out on gasoline, diesel oil, molten ghee, and wood crib fires, and the results compared with the similar tests conducted in Hefei. Water mist spray patterns under normal and low atmospheric pressures were characterized with a laser sheet method. Fuel mass burning rates were measured in both Lhasa and Hefei to investigate differences and influences on fire suppression. The experimental results showed that the burning rates of the above fuels are lower in Lhasa than in Hefei, and that mist droplets tended to congregate along the spray cone edge as the atmospheric pressure decreased. For most of the test cases, the fire suppression performance of water mist in Lhasa is a little better than that in Hefei, which may be largely caused by decreasing of the mass burning rate at lower atmospheric pressure conditions.

Evaluation of the Fire Suppression Effectiveness of Manually Applied Compressed-Air-Foam (CAF) System

Mobile compressed-air-foam (CAF) systems represent a new type of fire suppression system, which is gaining popularity among fire services. Properly engineered CAF systems produce superior quality foam with high momentum. However, until now, there has not been a study to systematically evaluate the fire suppression effectiveness of mobile CAF systems. NRC has carried out a project to evaluate the effectiveness of a mobile CAF system in suppressing fully developed compartment fires. Several full-scale compartment fire tests were conducted to compare the fire suppression performance of a manually applied CAF system with that of hose stream application using water alone and using water-foam solution, under similar conditions. The study showed that a CAF system is much more effective in suppressing the compartment fire compared to hose stream application with water only or with foam-water solution. A CAF system with a 95 L/min (25 GPM) water flow rate suppressed the test fire better than the hose-stream application with water only or with foam-solution using 360 L/min (95 GPM). The CAF system suppressed the fire and cooled down the fire compartment (to 200°C) much quicker than the water alone or foam-solution. Also, the total amount of water used to control the test fire was much less with the CAF system than with the water alone or foam-solution.

A new type of fire suppressant powder of NaHCO 3/zeolite nanocomposites with core–shell structure

A new type of particulate fire suppressant with core–shell structure was fabricated, in which zeolites 13X were encapsulated in the shell of nanosized sodium bicarbonate (NaHCO 3) particles. Laboratory-scale tests showed that thus-prepared nanocomposites displayed much-improved extinction efficiency than that of conventional sodium bicarbonate (NaHCO 3) dry powder with relatively shorter extinguishing time and less amount of agents required. Such an improved fire suppression performance could be reasonably ascribed to the unique core–shell structure and nanosize of the composite particles. The possible fire extinguishing mechanism of the composite powder was discussed, which involved the simultaneous functions of NaHCO 3 and zeolite.

Fire Performance Evaluation of a K-16.8 Suppression-mode Upright Sprinkler

Five large-scale rack-storage fire tests and supplemental Actual-Delivered-Density (ADD) measurements were conducted to determine whether a K-16.8, quick-response, upright sprinkler could provide fire suppression performance under horizontal ceilings 9.1m and 10.7m high. The designated sprinkler operating pressures were 241 and 345 kPa, respectively. The sprinkler spacing used in this evaluation was 3.1 μ 3.1 m. The fire hazard targeted under the 9.1-m high ceiling was up to that represented by rack-storage, expanded Group A plastics in cartons, and the fire challenge under the 10.7-m high ceiling was up to that of unexpanded Group A plastics in cartons, also stored in steel racks. In these tests, the prototype sprinkler demonstrated fire protection performance expected from a suppression-mode sprinkler within its intended applications. One of the tests conducted under the 9.1-m high ceiling showed that the sprinkler’s performance was little affected by the presence of a building bar joist obstruction inv...

Modelling Aspects of Sprinkler Spray Dynamics in Fires

Sprinklers are used extensively in a variety of fire protection applications. These systems are required to perform effectively over a wide range of extremely harsh and complex operating conditions. The sprinkler performance depends on the initiation, formation, dispersion and surface cooling characteristics of the sprays created by these devices. The behaviour of sprinkler sprays is strongly coupled with the fire dynamics in the surrounding environment, making characterization of these sprays and their corresponding performance quite challenging. The present paper provides a discussion of the important fundamental transport process for sprinkler sprays in fires. Mathematical models are provided for these processes in order to quantitatively characterize sprinkler spray performance. These mathematical models are well suited for incorporation into CFD codes or other fire modelling tools in order to analyze and predict fire suppression performance.

An Extrapolation Methodology For Pool Fire Extinguishment By Local Application Water Mist Systems

A series of fire tests was conducted to investigate the requirements for local application water mist systems to provide consistent fire suppression performance for different sizes of open pool fires. These tests were conducted with water mist nozzles arranged above square or rectangular diesel pools. The tests showed that a water mist system gives consistent fire suppression performance for pool fires of different sizes and aspect ratios if the system meets the following requirements: 1) constant nozzle operating conditions; 2) complete pool coverage by water mist sprays, 3) constant inclination angles for individual nozzles, 4) constant ratio of total number of nozzles versus the pool area; 5) constant ratio of overall spray coverage area versus pool area, and 6) constant nozzle elevation in the flaming region above the pool. The tests also showed that fire suppression performance could be improved by lowering the nozzle elevation and increasing the inclination angles of the nozzles along the pool perimeter under the experimental conditions used in this investigation.

Full-Scale Evaluation of Halon Replacement Agents

Full-scale fire suppression testing of HFC-227ea and HCFC Blend A was conducted in a 121 m3 compartment. HFC-227ea was tested at 7.6 and 8.8%; HCFC Blend A was tested at 8.6, 9.3, 10, 12 and 14% (by volume). Information on discharge characteristics and fire suppression performance of these halon replacement agents was obtained. HFC-227ea extinguished all test fires at the test concentrations. HCFC Blend A extin guished all test fires only at test concentrations of 12% or higher. These two agents produced halogenated acid gases whose quantity depended on the type, concentration and discharge of the agents and the size of the test fires. Language: en