Fire Suppression Performance Research Articles

The necessary water discharge density to suppress fires in premises

The paper presents experimental research findings for the temperature reduction of pyrolyzing and burning materials under typical indoor fire conditions when model fires are sprayed with varying water discharge density. The most typical combustible materials found in premises were considered. Two methods of extinguishing a model fire were investigated: continuous and cycling water mist discharge to the combustion zone. The velocities and average sizes of droplets in the aerosol flow were recorded of the experiments. Shadow Photography and Particle Image Velocimetry methods were used to record the aerosol parameters. An optical complex including a Quantel EverGreen 200 pulsed Nd:YAG laser and an ImperX IGV B2020M CCD camera was used. The findings revealed that a selective water supply system operation is required to suppress the combustion of different categories of materials. The values of the fire suppression performance index were calculated from the results of the experiments. • Irrigation density of at least 2.2 l/m 2 must be ensured for typical premises. • Irrigation density in the range of 11–18 l/m 2 must be ensured for wood based material. • Time of extinguishing for typical materials can vary >20-fold. • Fire extinguishing by impulse spraying reduces irrigation density by 60–70%. • The values of the extinction efficiency coefficient are within the range 0.03–1.

Fire testing of alternative fixed fire-extinguishing systems for ro-ro spaces onboard ships

ABSTRACT The International Convention for the Safety of Life at Sea (SOLAS) recognises five different fire-extinguishing system solutions for ro-ro spaces on ships; manually activated water spray systems (Resolution A.123(V)), automatic sprinkler or deluge water spray systems and automatic nozzle or deluge water mist systems (MSC.1/Circ.1430), high-expansion foam systems and gas fire-extinguishing systems (FSS Code). A review of potential commercially available alternative systems, their expected performance efficiency and water consumption was made. Based on this review, two alternative fire-extinguishing systems were identified: Compressed Air Foam Systems (CAFS) and foam-water sprinkler/spray systems. Fire suppression performance testing of water spray systems according to the Resolution A.123(V) and MSC.1/Circ.1430, a CAFS and a foam-water spray system were conducted. The water spray system per MSC.1/Circ.1430 had superior performance while the system per Resolution A.123(V) and the foam-water spray system limited the fire size to some degrees. The CAFS provided limited fire suppression performance.

A Comparative Evaluation of Natural and Synthetic Binder Systems and their Influence on the Thermal and Mechanical Properties of Gallic Acid‐KNO3‐KClO3 Tertiary Pyrotechnic Mixture

AbstractTannic acid is a natural binder that was comparatively investigated against four different types of conventional synthetic binders phenol‐formaldehyde resin, carboxymethyl cellulose sodium salt, ethylcellulose, and hydroxyethylcellulose which are being used in aerosol forming pyrotechnic formulations for firefighting application. It has been found that the nature of the binder in an amount of 3 % significantly influences the fire suppression performance, thermal and mechanical characteristics of gallic acid‐based aerosol‐forming pyrotechnic mixture. The safety and performance characteristics of these formulations were evaluated by conducting analysis specific to pyrotechnic formulations, i. e., calorimetric analysis, linear solid strand burn rate measurement, TGA/DSC thermal analysis, compression test, moisture content, and fire suppression test. These formulations were designed to discharge fire extinguishing aerosol and it can be inferred from the values obtained from these analyses that tannic acid is a preferred binder to the other four binder systems for the Gallic acid‐KNO3‐KClO3 pyrotechnic mixture.

Organophosphorus modified hollow bimetallic organic frameworks: Effective adsorption and catalytic charring of pyrolytic volatiles

Up to now, hollow metal organic frameworks (MOFs) usually possess a single metal element, and the size and shape of hollow structure cannot be reasonably tuned. In this work, novel organophosphorus modified hollow bimetallic organic frameworks (W-Zr-MOF-DOPO) are successful synthesized. Briefly, zirconium-based MOFs octahedron is first prepared according to a modified method, then hollow bimetallic MOFs are obtained by etching with WO42− under acidic condition, and organophosphorus is grafted onto it by the Kabachnik-Fields reaction. Inspiringly, the particle size of zirconium-based MOFs can be adjusted by the adding of acetic acid, thus acquiring hollow MOFs with controllable interior channels. The as obtained material is employed to reduce the fire risk of epoxy resin (EP), in which the hierarchical pores and metals can effectively facilitate the adsorption and catalytic charring of pyrolytic volatiles. Moreover, the P element of organophosphorus acts both in the condensed and gas phases, endowing EP with excellent thermal stability, fire retardancy and smoke suppression. The results indicate that the limiting oxygen index value of W-Zr-MOF-DOPO/EP composite increases from 24.6% (pure EP) to 32.2% and it can pass UL-94 V-0 rating when the additive amount is only 3 wt%. Especially, the total smoke production (14.5 m2) and peak heat release rate (403 kW m−2) of W-Zr-MOF-DOPO/EP composite decrease by up to 36% and 58%, respectively, compared with pure EP. Therefore, this work draws novel inspirations for the rational design of polymer composites with high fire retardancy and smoke suppression performance.

파랑 중 운동하는 선박 내부 소화 모니터의 소화수 거동 모델링

The present study aims to develop a simulation of water jet from a fire monitor working in a ship in seaways. The physics was simulated using Unity engine, composed of water jet trajectory and ship motion in waves. Regarding ship motion, the time history of the translational acceleration and rotation of the ship mass center were estimated based on the standards of ship motion and attitude by US Navy. The water jet behavior was simulated by implanting fluid motion library based on the particle approach. The water jet parameters were tuned by an empirical formula for water jet trajectory. Decrease of fire suppression performance in seaways was quantified by the delivery rate of the water particles to the fire source region.

Compatibility of aqueous film-forming foams (AFFF) with sea water

This contribution combines the observations from fire experiments with modelling of ionisation of fluorosurfactants to explain the compatibility of AFFF with sea water. We report detailed chemical structures of fluorosurfactants introduced into the firefighting foam market since the development of the so-called light water by the US Naval Research Laboratory (NRL) in late 1960s and study their ionisation constants (i.e., pKa). The analyses of recent formulations of foam concentrates indicate that, almost all of them include four species of high purity C6 fluorotelomer and non-fluorotelomer surfactants, which have their roots in fluorosurfactant chemistries developed by 3M, Ciba-Geigy and Elf Atochem (and its predecessors). The earliest fluorosurfactants emerged as derivatives of perfluorocarbon acyl and sulfonyl fluorides, from a series of discoveries made by the 3M Company. We review the foaming and filming technologies developed by 3M, derived from the products of electrochemical fluorination (ECF), comprising acidic, propane-sultone, acrylic and amine-oxide concentrates, with potassium perfluorooctane sulfonate (K-PFOS) filmers used together with the sultone and acrylic foamers. To the best of our knowledge, these chemistries have not been documented in one reference in the open literature, and some of the chemicals used have not yet been identified in the environment. While we do not cover the development of fluorotelomer chemistries in the same detail, we discuss the fluorotelomer surfactants that have proven themselves to be successful in compatibility with sea water and compare their structure with those of the ECF-derived chemicals. We discovered that, the chemical compatibility with sea water is related to the formation of the specific ionised species that combine with divalent alkaline-earth metal cations to form ionic assemblies in the premix (solution made by mixing foam concentrates with water). These species arise at high pH values that are characteristic of sea water. We also reveal that, changes in the ionisation state of amine-oxide and tertiary-amine head groups, as pH varies between that of fresh and sea-water premix, may impact the performance of fluorosurfactants. The physical compatibility of fluorosurfactants with sea water manifests itself by shielding of the ionised head groups by metal cations decreasing the surface tension and modifying the size, shape and diffusion of micelles. For foam concentrates that satisfy the necessary condition of chemically compatible with sea water, the physical effect usually improves the foam quality and the fire-suppression performance of AFFF. We analyse in detail the patent literature and the early NRL reports to gain an intimate understanding of the first formulations introduced by the 3M Company. Although PFOS has been banned internationally, Chinese manufacturers produce PFOS-type concentrates for the domestic market, in addition to fluorotelomer surfactants destined for export. We provide detailed formulations of all types of concentrates that employed the ECF-based fluorosurfactant technologies, including hydrocarbon surfactants, solvents, corrosion inhibitors and buffers and link the chemical composition of the concentrates with the firefighting performance of the foams. We outline the correlations between the ionisation states of fluorosurfactants and their fundamental properties, such as surface packing and interfacial tension and comment that very little is known about these critical structure-activity relationships. Finally, we stress the need to reboot the progress in the field and give directions for future research.

Inhibition Effect of Thermally-Induced Fire in 21,700 Lithium-Ion Battery With Low-Pressure Twin-Fluid Water Mist

Abstract The fire hazard of lithium-ion batteries (LIBs) poses a serious threat to their transportation and use. The purpose of this study is to investigate the efficiency of low-pressure twin-fluid water mist (TFWM) on suppressing lithium-ion battery fires. Experiments were executed to research the effect of working pressures and release stages on extinguishing the fire. Aqueous vermiculite dispersion (AVD), a commercial agent that was specifically designed to extinguish battery fires, was chosen to compare with the fire suppression performance of TFWM under the same conditions. The results indicate that the type 21,700 LIB fires could be controlled by applying the water mist within 10 s. The cooling ability at various working pressures (0.4, 0.8, 1.0, and 1.2 MPa) demonstrated an increase in inhibitory effects as the working pressure increased, and the optimal pressure was 1.2 MPa. The results further show that the extinguishing ability of the TFWM was better than the AVD agent. When the water mist was applied at the optimal working pressure, the surface temperature, flame temperature and concentration of CO reduced more significantly, compared with the AVD agent. Therefore, the TFWM shows considerable merit as a candidate to fight LIB fires.

High efficiency of the NH4H2PO4/Mg(OH)2 composite for guaranteeing safety of wood production

Currently, China's timber industry is in high demand with the development of real estate. However, there is a certain fire hazard in the production process of wood manufacturing. Once a fire occurs, the fire is violent and the spread is rapid. Therefore, to improve the safety of its production process, ammonium dihydrogen phosphate and magnesium hydroxide were selected to prepare a new composite superfine dry powder, which was denoted as the NH4H2PO4/Mg(OH)2 composite. Furthermore, to figure out dry powders' extinction effect on Class A fire, the wood-crib fire suppression effect of the NH4H2PO4/Mg(OH)2 composite was test, and then compared with that of ultrafine dry powder (UDP) and commercial ABC dry powder (C-ABC) in a 1 m³ chamber. Three parameters of the fire extinguishing process, namely flame extinction time, powder consumption and temperature drop were adopted to measure the fire suppression performance. The results demonstrated that UDP and C-ABC both had a larger flame extinction time and powder consumption than the NH4H2PO4/Mg(OH)2 composite. Besides, a fire (wood cribs) can be extinguished by the NH4H2PO4/Mg(OH)2 composite with the fastest temperature drop and a much-improved toxic gas suppression ability. In short, the NH4H2PO4/Mg(OH)2 composite can better guarantee the safety of the wood processing production process. Moreover, the reasons for performance advantages of the NH4H2PO4/Mg(OH)2 composite were discussed.

Full-scale experimental study on water mist fire suppression in a railway tunnel rescue station: Temperature distribution characteristics

Rescue stations are essential for emergency evacuation in super-long railway tunnels. However, the deficiency of related studies aiming at improving the fire suppression performance of water mist system in fire scenarios limits its application significantly. In this work, 20 sets of full-scale water mist fire suppression experiments were conducted to examine the impacts of water mist system on smoke temperature characteristics, including water mist activation time (denoted by t), working pressure (P), k-factor (K) and longitudinal wind speed. Results show that when t = 3 min, P = 12 MPa, and K = 0.5, the best performance of temperature control could be achieved. Although there are violent temperature fluctuations in the train side, the smoke temperature could be easily restrained. Moreover, it is found that longitudinal ventilation is helpful to improve the visibility at platform and reduce smoke temperature. When P = 12 MPa, the coupling effect of water mist and longitudinal ventilation on cooling smoke is better. In addition, the non-dimensional maximum temperature rise is found to show a great cubical dependency on vertical height, and decreases along with a larger longitudinal distance for all cases. Also, under longitudinal ventilation, the non-dimensional maximum temperature rises are lower than that without longitudinal ventilation in the coverage area of water mist. Results of this work can provide a significant reference for the design of water mist system in railway tunnel rescue stations.

A Study on the Development of Fire Extinguishing Agent and Extinguishing System for ESS Fire

This paper presents a study on the development of a fire extinguishing agent and extinguishing system for an energy storage system (ESS) fire. The fire extinguishing agent designed to extinguish an ESS fire is a highly permeable fire extinguisher that reduces the surface tension and viscosity while bringing about cooling action. This is the main extinguishing effect of this type of wetting agent, which displays the characteristics of fire extinguishing agents used for penetrating the battery cells inside the ESS module. For the fire extinguishing system, a local application system was designed to suppress fire on a rack-by-rack basis. A 360° rotating nozzle was inserted into the rear hall of the ESS module, and general nozzles were installed in the rack to maximize the fire extinguishing effect. The fire extinguishing agent was strongly discharged by virtue of the gas release pressure. Experiments on fire suppression performance with ESS module 1 unit and module 3 units showed that all visible flames were extinguished in 8 s and 9 s, respectively, by the fire extinguishing agent. In addition, based on confirming reignition for 600 s after the fire extinguishing agent was exhausted, it was confirmed that the ESS fire was completely extinguished without reignition in all fire suppression performance experiments.

Experimental study on the pulse water mist fire suppression system performance in a confined space

Water mist system is used widely in confined spaces, where fire protection and suppression efficiency is very important due to limited water and no water damage. Pulsed water mist is a new type of fire extinguishing system that sprays and pauses in cycle during the procedure of fire extinguishment. Focusing on the fire suppression performance of pause water mist system, a series of experiments have been conducted to explore a more effective pause cycle way, fire suppression behavior, and the temperature distribution in a confined space. The results can be found that the best fire extinguishing effect was achieved with a pulse cycle alternating between an 8-s activation and an 8-s deactivation. With the increase in size of the vents, the advantage of the pulse water mist system gradually diminishes. The smothering method is better than the cooling method. The results of the study may provide a reliable reference for the practical application of pulsed water mist system.

Pool fire suppression performance by twin‐fluid water mist under low pressures in an altitude chamber

AbstractFire suppression tests using low pressure twin‐fluid water mist under low pressure environments were carried out to exam the performance of water mist systems at low pressure environments. The experiment results show that the suppression time gets shorter for lower chamber pressure, and relevant total weight of water and nitrogen used decreases as the chamber pressure gets lower. For the case of 30‐cm diameter pool fire, the suppression times are 20.19, 7.5, and 2.24 under the chamber pressure of 60, 38, and 24 kPa, respectively. In case of a cargo compartments fire, it is suggested to open the ventilation valve of the cargo compartment at a high cruising altitude to relieve pressure, so as to achieve rapid fire suppression. When a fire happens at the position off the center below the water mist nozzle, the water mist suppression effects will be weakened. The fire size has little effects on the fire extinguishing process under pressure of 24 kPa. Under the critical atomization condition with the pressure differential between the inlet and outlet of the nozzle for water as 0.05 MPa (5.04 L/min), and the pressure differential for nitrogen as 0.10 MPa (10.97 L/min), the suppression time is the shortest as 18.66 seconds.

Smoke suppression performance of polyurethane composites containing microencapsulated melamine polyphosphate

A novel microencapsulated flame retardant containing melamine polyphosphate (MPP) and 4,4[Formula: see text]-oxydianiline-formaldehyde (OF) resin as a core–shell material was synthesized using in situ polymerization. The flame retardant was added to polyurethane (PU) to improve the fire suppression performance of resulting materials. Polyurethane was modified by silane, which was called as Si–PU and MPP was microencapsulated by OF resin, which was OFMPP. The results indicated that the smoke obscuration index (SOI) values of Si–PU, Si–PU/MPP 30% and Si–PU/OFMPP 30% were 6.59, 3.04 and 1.16, respectively, which indicated that the addition of flame retardants causes a significant downward trend in SOI values. The SOI value of Si–PU/OFMPP 30% was lower than that of Si–PU/MPP 30%, indicating that the microencapsulated OFMPP achieved smoke suppression.

Synergistic Effects of Two-Dimensional MXene and Ammonium Polyphosphate on Enhancing the Fire Safety of Polyvinyl Alcohol Composite Aerogels.

Fire and smoke suppressions of polyvinyl alcohol (PVA) aerogels are urgently required due to the serious fire hazard they present. MXene, a 2D transition-metal carbide with many excellent properties, is considered a promising synergist for providing excellent flame retardant performance. PVA/ammonium polyphosphate (APP)/transition metal carbide (MXene) composite aerogels were prepared via the freeze-drying method to enhance the flame retardancy. Thermogravimetric analysis, limiting oxygen index, vertical burning, and cone calorimeter tests were executed to investigate the thermal stability and flame retardancy of PVA/APP/MXene (PAM) composite aerogels. The results demonstrated that MXene boosted the flame retardancy of PVA-APP, and that PAM-2 (with 2.0 wt% MXene loading) passed the V-0 rating, and reached a maximum LOI value of 42%; Moreover, MXene endowed the PVA-APP system with excellent fire and smoke suppression performance, as the the peak heat release rate and peak smoke production rate were significantly reduced by 55% and 74% at 1.0 wt% MXene loading. The flame retardant mechanism was systematically studied, MXene facilitated the generation of compact intumescent residues via ita catalyst effects, thus further restraining the release of heat and smoke. This work provides a simple route to improve the flame retardancy of PVA aerogels via the synergistic effect of MXene and APP.

Suppression of propane cup-burner flame with HFO-1336mzz(Z) and its thermal stability study

Cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) conforms the most of necessary requirements as an environment-friendly extinguishant. However, its fire suppression performance has not been investigated. In this study, the fire suppression effectiveness of HFO-1336 was evaluated by a cup burner apparatus. The extinguishing concentration indicates nonpositive correlation with the fuel flow. On the other hand, to characterize the heat release of the reaction kernel, the temperature of the flame base was measured. The results showed that the temperature increased with HFO-1336 loading in the range of 2–5 %, while decreased as the concentration exceeded 5 %. In addition, the thermal decomposition properties of HFO-1336 were investigated over a temperature range of 100–800 ℃ and the products were analyzed by GC–MS. According to the detected products, the possible decomposition pathways were proposed and the extinguishing mechanism were discussed.

Fire suppression performance of a new type of composite superfine dry powder

SummaryTo enhance the performance of existing dry powders and ensure process security, a new type of dry powder based on ammonium dihydrogen phosphate (NH4H2PO4) was prepared. The prepared composite superfine dry powder was denoted as NH4H2PO4/zeolite composite in this paper. The effectiveness of commercial ABC dry powder, superfine dry powder, and the NH4H2PO4/zeolite composite in fire suppression were compared in a small‐sized fire‐extinguishing chamber. Laboratory‐scale tests showed that the NH4H2PO4/zeolite composite had considerably superior fire‐extinguishing efficiency to that of commercial ABC dry powder and superfine dry powder, along with shorter average extinguishing time and less average mass of powders consumed. In addition, the NH4H2PO4/zeolite composite also displayed much improved toxic gas suppression ability. The physical and chemical characteristics of commercial ABC dry powder, superfine dry powder, and the NH4H2PO4/zeolite composite were characterized using a range of techniques of laser particle size analysis, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Based on the analysis results, the improved fire suppression performance of the NH4H2PO4/zeolite composite can be ascribed to smaller particle size, larger surface area, and a special chemical decomposition process.

Synergisms between siloxane-polyoxyethylene and alkyl polyglycoside surfactants in foam stability and pool fire extinction

Fluorocarbon surfactants in firefighting foams must be replaced with environmentally friendly surfactants without loss of fire suppression performance. Aqueous foams generated from commercial siloxane-polyoxyethylene and alkyl polyglycoside surfactants were characterized individually and as mixtures in a formulation by measuring the solution and foam properties, foam degradation and fuel transport rates through a foam layer on a hot heptane pool, and foam’s ability to suppress a heptane pool fire rapidly using minimum amount of foam. The results showed significantly smaller fire extinction times for the surfactant mixtures than for either of the individual components exhibiting a synergistic fire extinction rather than following the law of averages; 5 times enhancement in extinction performance. The measured foam degradation rate with the foam exposed to a hot heptane pool also showed a similar synergism. The reduced foam degradation rate resulted in a reduced fuel vapor transport for longer times and a more rapid fire extinction for the siloxane-glycoside mixture. By increasing the hydrophilicity with increased size of the polyglycoside head, the synergistic effect was enhanced. Both benchtop (19 cm diameter) and large scale (6 ft diameter) heptane pool fire extinction with the siloxane-glycoside surfactant mixture showed that the extinction time was 1.5 times (60% effectiveness of AFFF) that of an equivalent AFFF formulation containing a fluorosurfactant in place of the siloxane surfactant at a fixed foam application rate (22 L m−2 min−1). An understanding of the molecular interactions at the interface causing the synergistic effects may lead to improved siloxane-glycoside systems and other novel surfactant systems with performance matching that of fluorocarbon surfactants.

Modulation of fluorocarbon surfactant diffusion with diethylene glycol butyl ether for improved foam characteristics and fire suppression

Analysis of aqueous solutions comprised of a fluorocarbon-betaine surfactant with and without diethylene glycol butyl ether (DGBE) have provided insight into the effect of DGBE on fire suppression and foam quality. Incorporation of DGBE decreased the Sauter mean bubble size and liquid drainage that resulted in faster foam spread, which lead to improved fire suppression performance at slow foam application rates. The DGBE effects were found to be relatively small at fast foam application rates. Dynamic surface tension characterization showed that diffusion of the surfactant was more rapid in the water-DGBE solvent system such that the air-liquid interface could have stabilized faster thus resulting in a smaller bubble size. The faster surfactant diffusion in the presence of DGBE is consistent with the measurements of larger micelle diffusion coefficients and smaller micelle sizes when DGBE is included with the fluorocarbon surfactant. Smaller observed micelle size provides evidence of the incorporation of DGBE into the fluorocarbon surfactant micelle within the palisade layer thus altering the micelle composition and size. Measurements of bubble size, dynamic surface tension and micelle size support altered fluorocarbon surfactant behavior in solution which resulted in the generation of a more stable foam capable of faster foam spread and fire suppression as a result of the presence of DGBE in solution.

Study on Characteristics of Self-rotating Spray with Pre-mixed Compressed Air and Low-pressure Water for Extinguishing Class B fires

In view of the high-pressure water mist application problems, a method of self-rotating spray extinguishing class B fires was put forward with the pre-mixed compressed air and low-pressure water.The self-rotating spray fire extinguishing system of pre-mixed compressed air and low-pressure water and a high-pressure water mist fire extinguishing testing system were established, and the spray performance and fire suppression performance were tested respectively. The results showed that the self-rotating spray had finer and more evenly droplets, bigger effective spray radius, lower system pressure, more reduction in water quality requirements, less clogging nozzle than the high-pressure water mist under the basically same water consumption. The effective fire extinguishing distance of self-rotating spray fire was 2.5m and the effective fire extinguishing radius was 1.5m, which was better and would be more applicable for engineering applications than high-pressure spray fire extinguisher.

Polyurethane foams with functionalized graphene towards high fire-resistance, low smoke release, superior thermal insulation

To overcome the contradiction among flame retardancy, smoke suppression and thermal insulation for polyurethane foams (PUFs), in this manuscript, a novel functionalized graphene (FGN) is designed and prepared from expandable graphite (EG) and phosphorus-containing compounds. This FGN decorated with phosphorus-containing epoxy shows excellent compatibility with polyurethane matrix, leading to an improved compressive strength and decreased thermal conductivity as low as 0.02975 W/(m∙K). Notably, the resultant PUFs with FGNs exhibit great fire resistance and smoke suppression performance. With only 50 pphp FGNs (6.1 wt%) incorporated, the composite foam can pass the UL-94V-0 rating with a high limiting oxygen index value of 27. More importantly, the incorparation of FGNs not only effectively reduces the heat release rate (HRR) and total release rate (THR) of PUFs, but also significantly suppresses smoke release of materials during combustion. The mean specific extinction area (mSEA) and total smoke production (TSP) values of the composite foam can be reduced to 208.52 m2/s (−70.0%) and 2.08 m2/m2 (−66.0%), respectively. These characteristics with high fire resistance, excellent smoke suppression and low thermal conductivity very beneficial for polyurethane foams used as thermal isolation materials.