Cup Burner Research Articles

Experimental and numerical evaluation of metallic compounds for suppressing cup-burner flames

The first tests of supereffective flame inhibitors blended with CO 2 have been performed in methane–air laminar co-flow diffusion flames stabilized on a cup burner. The CO 2 volume fraction required to extinguish the flames was determined for a range of added catalytic inhibitor volume fractions. When added at low volume fraction, the agents TMT, Fe(CO) 5, and MMT were effective at reducing the volume of CO 2 required to extinguish the flames, with performance relative to CF 3Br of 2, 4, and 8, respectively. This performance advantage of the metallic compounds is less than that determined in premixed or counterflow diffusion flames. Further, as the volume fraction of each metallic catalytic inhibitor was increased, the effectiveness diminished rapidly. The greatly reduced marginal effectiveness is believed to be caused by loss of active gas-phase species to condensed-phase particles. Laser-scattering measurements in flames with Fe(CO) 5/CO 2 blends detected particles both inside and outside (but not coincident with) the visible flame location for measurement points above the stabilization region. For Fe(CO) 5 addition to the air stream at 450 μL/L, the peak scattering cross section for vertically polarized light was 1660 times the value for room-temperature air. The first detailed numerical modeling studies were also performed for methane–air cup-burner flames with CO 2 and Fe(CO) 5 added to the oxidizer stream and are used to interpret the experimental results. The role of particles was also illustrated by the numerical results, which showed that significant levels of supersaturation exist in the flame for several of the important iron-containing intermediates. This particle formation is favored in the lower temperature stabilization region of the cup-burner flames, as compared to the higher relevant temperatures of previously described counterflow diffusion flames. The results of this study indicate that the appropriate flame configuration for evaluating the effectiveness of some fire suppression agents must be carefully considered, since in those cases, different flame configurations can switch the relative performance of an agent by an order of magnitude.

Suppression of cup-burner flames using carbon dioxide in microgravity

The extinguishment characteristics of CO 2 as a fire-suppressing agent have been studied experimentally and numerically using a methane–air laminar co-flow diffusion flame stabilized on a cup burner. Direct numerical simulations of cup-burner flames under various gravitational forces were performed using a time-dependent, axisymmetric mathematical model with a detailed-chemical-kinetic mechanism for CH 4/O 2 combustion. Experiments with cup-burner flames under normal-gravity (1 g) conditions were performed for comparison purposes. Both the computed flicker frequency and the predicted critical concentration of CO 2 for extinguishing the flame compared well with the respective quantities measured in the experiments. As the buoyancy force is reduced, the flicker frequency decreases, the flame diameter increases, the tip opens, and the base becomes vertical. It is predicted that the cup-burner flame ceases to flicker for gravitational forces corresponding to less than 0.5 g. Numerical experiments revealed that radiative heat loss is predominantly responsible for flame quenching (opening) in the tip region under microgravity (0 g) conditions. In contrast, 1 g flames are affected only slightly by the radiative heat loss. Calculations are made by adding different amounts of CO 2 to the air stream for obtaining the critical volume fraction of CO 2 to extinguish 0 g flames. The behavior is similar to that observed in 1 g flames: the addition of CO 2 destabilizes the flame base, which then moves downstream in search of a new stabilization location. For CO 2 volume fractions greater than 19.1%, the flame base moves out of the computational area, as it cannot find a stabilization point within the domain. This critical concentration for the 0 g flames is ∼32% higher than that computed for the same flames under 1 g conditions. Calculations made by ignoring radiation for the limiting flame under 0 g conditions yielded a stable flame. This study suggests that it is important to consider radiation heat losses when estimating the extinguishment limits of cup-burner flames in microgravity.

Fire-extinguishing effectiveness of new binary agents

The search for a new fire-extinguishing agent with all the desirable properties of halon 1301 has not been successful. During the last few years, several chemical groups with very low extinguishing concentrations have been identified. Most of these compounds have high boiling points and are not suitable replacements for halon 1301. However, mixtures of these chemicals in an inert gas could produce fire-extinguishing agents with many of the desirable properties of halon 1301. To study binary fire suppressants, one has to determine the extinguishing concentrations for several compositions of a given chemical in an inert gas. This process is expensive and time consuming. A method to estimate the extinguishing concentrations would be helpful in reducing the number of experiments needed for any binary system. In this study, a method based on adiabatic flame temperature calculations and the dependence of the rate of fire suppression of chemical agents on temperature was used to estimate the extinguishing concentration of binary mixtures. The method was tested for five organic compound/nitrogen mixtures. Five compounds that have been shown to have very low extinguishing concentrations and very short atmospheric lifetime were selected for this study. Cup burner experiments were conducted for several concentrations of each chemical in nitrogen. All the five binary systems showed synergism. As expected, the degree of synergism was highest at low concentrations of the chemical. For each binary system, extinguishing concentrations of the pure compounds and one binary data were used to predict the extinguishing concentrations for the entire range of binary composition. The predicted values are very close to experimental data.

Numerical Investigations Of CO2 As Fire Suppressing Agent

CF3Br (Halon 1301) and inert gases is useful for their efficient use and for developing new agents. Because of the similarities between unsteady jet diffusion flames formed over the cup burner and uncontrolled fires, it is believed that studies of fire-suppressing agents in the former system could provide valuable information on the behavior of such agents in actual fires. In the present study, suppression characteristics of CO² were investigated in two flame systems: 1) a periodically oscillating, methane-air jet diffusion flame formed over a cup burner, and 2) a steady-state planar flame formed between opposing jets of fuel and air. A detailed chemical-kinetics model having 31 species and 346 elementary-reaction steps was used. Calculations made for the cup burner yielded a flame-flicker frequency of about 10 Hz. The suppression mechanisms promoted by CO² were investigated by adding CO² to the airflow, while maintaining the total flow rate constant, for both the cup-burner and opposed-jet flames. In the cup-burner flame, the addition of CO² reduced the flame temperature to ~1620 K at suppression. Addition of CO² destabilized the flame base, which then moved downstream in search of a new stabilization location. For CO² volume fractions greater than 14.5 %, the flame base moved out of the computational area, as it could not find a stabilization point within this domain. The unsteady flickering motion of the flame and higher concentrations of CO² accelerated this quenching process through blowout. Even for very high concentrations of CO², the calculations did not yield simultaneous quenching of the entire cup-burner flame. On the other hand, the opposed-jet flame was extinguished through the global extinction of flame chemistry. The low-strain (30 s-1) opposed-jet flame extinguished for CO² volume fractions > 16.4 %, while the moderately strained (90 s-1) flame extinguished for volume fractions > 10.4 %. Both the opposed-jet flames extinguished nearly at the same flame temperature (~1580 K), indicating that the extinction limits in these flames are primarily controlled by chemical kinetics.

Fire Suppression And Re-ignition Prevention Ina Full-scale Engine Nacelle Simulator

An analysis is presented on the full-scale fire suppression experiments conducted on the F-22 engine nacelle simulator at Wright Patterson Air Force Base. Experiments investigated the relative effectiveness of halogenated agents and solid propellant gas generators (SPGG) in suppressing a series of spray fires with and without a fuel re-ignition source. Several agents were tested including CF3Br (halon 1301), C2HF5 (HFC-125), and two basic types of SPGG, including one that produced inert gases in conjunction with a fine solid particulate composed of K2CO3 and one that produced inert gases only. The measured agent effectiveness was compared to the predicted effectiveness based on results from cup burner suppression experiments. Estimates of the suppression effectiveness of the SPGG were based on the effectiveness of the components of its effluent. The mass fraction of SPGG effluent required to extinguish heptane cup burner flames was estimated as 0.15 and 0.29 as compared to previously measured values of 0.14 and 0.28 for CF3Br and C2HF5, respectively. The predicted suppression requirements (relative to CF3Br) agreed with the full-scale measurements within 35% for the halogenated compounds, whereas the SPGG performed as much as a factor of 3.3 better than predicted. This difference suggests that a large fraction of the SPGG performance may have been related to its fast deployment, which enhances flame straining and thereby reduces agent mass suppression requirements. The SPGG effluent that contained a significant percentage of K2CO3 particulate was particularly effective for re-ignition protection, a scenario that dominates agent mass requirements for the compressed halogenated liquids. In this case, the SPGG required 27 times less mass than CF3Br. INTRODUCTION Halon 1301, or trifluorobromomethane (CF3Br), has been used as a fire extinguishing agent in many applications because of its many positive attributes. Due to its high ozone depletion potential, however, its production has been terminated. In the search for a suitable replacement, novel types of agents are under development. One class of such devices is the solid propellant gas generator (SPGG), a device in which solid-phase combustion yields products which can be used for fire suppression [1]. The key parameters that affect flame stability, control flame extinction and the prevention of re-ignition are agent effectiveness and flow field dynamics. Whereas there is a general understanding of the suppression mechanisms of gaseous agents, little has been published on SPGG effectiveness. Recently, the relative suppression effectiveness of a SPGG has been Copyright © International Association for Fire Safety Science 704 measured in a well-controlled bench-scale experiments [2]. There are many types of SPGG, each with its own composition, packaging geometry, and ignition sequencing. It is expected that gas specie and particulate yields, particulate size distributions, exhaust temperatures, and the rate and duration of effluent generation will vary from one SPGG to another, and each of these parameters may impact SPGG effectiveness. Table 1 shows the species composition of the SPGG effluent for the formulations tested here. For interest, a hypothetical mixture of unfiltered effluent from SPGG 1 is also included. Several SPGG types from Manufacturer 1 were tested and all were assumed to have the same effluent composition [3]. The hot exhaust products were principally gaseous N2, CO2, and H2O vapor and salt particulates. Table 1 shows that there was approximately one-third as much CO2, more than twice as much H2O, and almost two-thirds as much N2 produced in the SPGG 2 effluent than in the filtered SPGG 1 effluent. The SPGG 2 effluent is assumed to be unfiltered, so that it contains K2CO3(s), whereas the filtered SPGG 1 effluent is assumed to contain trace amounts of particulate only. Particle size can influence suppression effectiveness [4]. The majority of the SPGG particulate is very small and it is assumed that the particulate is smaller than the critical diameter [4]. To investigate the suppression effectiveness of SPGG in a simulated F-22 engine nacelle, a series of full-scale fire experiments was undertaken utilizing the Wright Patterson Aircraft Engine Nacelle Test Facility. The experiments described here investigated the relative effectiveness of halogenated agents and SPGG in suppressing spray fires with and without a re-ignition source. Several SPGG types were tested, including one that produced inert gases and a fine solid particulate, and one with the particulate filtered, such that only inert gases were emitted. Table 1 SPGG mole based fractional effluent composition. Species filtered SPGG 1 Unfiltered SPGG 1 SPGG 2 CO2 0.313 0.264 0.0917 H2O 0.219 0.183 0.559 N2 0.468 0.395 0.325 K2CO3 0* 0.158 0.0246 * assumed to be trace amounts only. _______________________________ * Certain commercial materials and equipment are identified in this report in order to specify adequately the procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the material or equipment is necessarily the best for the purpose.

A screening tool for Halon alternatives based on the flame ionisation detector

A standard flame ionisation detector (FID) of the type used in gas chromatography experiments has been modified to enable flame extinguishing concentrations to be determined. Good agreement with Cup Burner data (a preferred fire extinguishing performance indicator) has been obtained for a number of gaseous Halon alternatives. The fact that only small quantities of these compounds (<1 g) are required for the test makes it an ideal tool for the assessment of novel compounds which may only be available in small quantities. The potential of the technique has been demonstrated by application to the study of novel phosphorous-containing compounds (PCCs) which were shown to be between two to four times more efficient than Halons.

Fire Protection with Bromoalkene/Nitrogen Gaseous Mixtures

The fire suppression efficiencies of 1-bromo-1-propene/nitrogen and 2-bromo-3,3,3 trifluoro-1-propene/nitrogen gas mixtures were studied by a cup burner method. It was shown that addition of 1-bromo-1-propene and 2-bromo-3,3,3 trifluoro-1-propene to nitrogen can improve the suppression effectiveness of the inert gas by 34.5 and 64.3%, respectively. An arrangement for mixing organic compounds with inert gases before application to fire was proposed, and it was shown that droplets of bromoalkenes with diameters as large as 100 μm can be vaporized in less than 1 s.

Fire extinguishing ability of 1-bromo-1-propane and 1-methoxynonafluorobutane evaluated by cup burner method

The fire extinguishing ability of 1-bromo-1-propane/nitrogen (the molecular formula of 1-bromo-1-propane: CH 3–CH 2CH 2Br) and 1-methoxynonafluorobutane/nitrogen gas mixtures (the molecular formula of 1-methoxynonafluorobutane: CF 3CF 2CF 2CF 2OCH 3) as total flooding agents were evaluated by a cup burner method. It was shown that addition of small amounts of 1-bromo-1-propane and 1-methoxynonafluorobutane to nitrogen can enhance the extinguishing ability of the inert gas by 47.1 and 31.5%, respectively, and the relative of the extinguishing concentration to the concentration of 1-bromo-1-propane or 1-methoxynonafluorobutane in the flooding agents is: Y=5.18866+26.72165 e −X/11.07715 or Y=5.96301+23.59368 e −X/22.46021 . Meanwhile, an arrangement for mixing organic compounds with inert gases (N 2) before applying to fire was proposed.

Fire extinguishing ability of perfluoroalkylamines and perfluoroethers evaluated by a small cup burner method

The fire extinguishing abilities of (CF 3) 2NC 2F 5, (CF 3) 3N, (CF 3) 2NCHF 2, CF 3OC 2F 5, CF 3OCHFCF 3, and CF 3OCFCF 2 were evaluated using a small cup burner method. It was found that perfluoroalkylamines exhibit good fire extinguishing abilities.

Production of boron powder by arc volatilization : T.Hagio et al.J. Mater. Science, Letters, vol 17, no 22, 1998, 1937–1939

This chapter provides an overview of furnace oil burners. Fuel oils burn readily only in vaporized or gaseous state. The pot-type vaporizing burner can be used for the lighter fractions of gas oils, but combustion appliances using heavier fuel oils require special atomizing equipment for efficient combustion. Fuel-oil atomizers operate on two principles: (1) atomization by mechanical means, for example, pressure jet and rotary cup atomizers and (2) atomization by means of an atomizing fluid, for example, air at low, medium or high pressures, or steam. Pressure jet burner is the oldest type of mechanical atomizer and is still commonly used for large land and marine boilers. Rotary cup burner is a comparatively new burner, suitable for use with small installations and capable of using a variety of oil feeds without major modification. The chapter also discusses combustion characteristics of fuel oils. Combustion takes place initially in the vapor phase, so that evaporation or atomization must be sufficient to initiate combustion. After ignition, heat is supplied by the flame and by surrounding heated surfaces. With heavy residual oils and coal-tar products, a large oil film area is necessary to maintain combustion.

Suppression of nonpremixed flames by fluorinated ethanes and propanes

Suppression of methane/air and propane/air nonpremixed counterflow flames, and n-heptane and methanol cup burner flames by fluorinated hydrocarbons was investigated. Four fluorinated ethanes, 10 fluorinated propanes, four bromine- or iodine-containing halons, and the inert agents CF 4, SF 6, and N 2 were tested in some or all of the flames. Laser Doppler velocimetry (LDV) determinations of peak velocity gradients in the oxidizer flow of the counterflow flames were found to be linearly correlated with the expression for global strain rate derived for plug flow boundary conditions. This correlation was used to estimate strain rate values at extinction. The bromine- or iodine-containing agents are more effective on a molar basis than the fluorinated propanes, followed by the fluorinated ethanes, and finally SF 6, CF 4, and N 2. Agent effectiveness increases with the number of CF 3 groups present in the agent molecular structure. Numerical investigations of the flame speed reduction of methane/air mixtures doped with either CHF 2CHF 2 or CF 3CH 2F predict that the latter is the better agent, in accord with experimental observations. Chemical contributions to suppression account for less than 35% of the total suppression offered by fluorinated hydrocarbons not containing bromine or iodine. At strain rates below 100 s −1, suppression effectiveness rankings in methane and propane counterflow flames are similar to those obtained in n-heptane and methanol cup burner flames. Methanol flames are more difficult to extinguish than the alkane flames investigated, particularly with the chemical agent CF 3Br.

Evaluation of fire suppression ability of perfluoroalkylamines by cup burner method

The fire extinguishing abilities of perfluoro( N, N-dimethylethyl)amine, perfluorotrimethylamine, and N, N-bis(trifluoromethyl)difluoromethylamine were evaluated by a small-scaled cup burner method.

Flame extinction by sodium bicarbonate powder in a cup burner

An apparatus was developed for testing the extinction efficiency of a solid powder in a coflowing nonpremixed flame. Extinction measurements were performed by adding agent quasistatically to the oxidizer stream until flame extinction was observed. The concentration of powder agent was monitored by laser transmission. Extinction measurements were performed on flames burning both liquids and gases using sodium bicarbonate (NaHCO 3 ) powder as the extinguishing agent. For comparison, extinction measurements were also conducted using the gaseous agents, CF 3 Br (halon 1301) and N 2 . Tests were conducted using a number of fuels including heptane, two jet fuels (JP-8 and JP-5), two hydraulic fluids (83282 and 5606), as well as propane. The agent extinction requirements for the two small particle sizes tested here were highly similar. The results showed that on average, NaHCO 3 was three times more effective than CF 3 Br and five times more effective than N 2 on a mass basis in extinguishing flames burning the various fuels. An estimate of agent behavior based on the effectiveness of inert N 2 showed that whereas CF 3 Br acted primarily through chemical kinetic effects, only half of the effectiveness of NaHCO 3 could be attributed to kinetics.

A New Total Flooding Test Procedure for Evaluating Fire-Suppressant Agents

A simple laboratory apparatus is described for observing the performance of fire extinguishing agents in total flooding applications. Known compositions of agents mixed with dry air are prepared in a 2 L glass combustion flask, and a flame fed by propane, butane, or other gaseous fuel from a pressure cylinder is inserted into the flask through a standard taper joint. Burning times to extinguishment are measured, both in the absence and presence of added physical or chemical agents. From the known rate of propane burning and initial compositions, the percentages of gas volume in the combustion flask at extinguishment are calculated for each burning time. Agents that are not sufficiently volatile to be investigated with the ordinary cup burner method are readily studied with the new technique.

Fire Extinguishing Effect Of Mixed Agents Of Halon 1301 And Inert Gases

Multiplier effect of mixed agents of trifluorobromomethane (halon 1301) and inert gases on flame extinction has been investigated, for the purpose of minimizing the use of halons. The inert gases examined are argon, nitrogen and carbon dioxide. The fire-extinguishing efficiency was determined by flame-extinguishing concentrations for n-heptane measured with a cup burner. An additive-property equation was derived by thermodynamic considerations to predict the fire-extinguishing efficiency of mixed agents and used as a measure of multiplier-effect test. The mixed agents of halon 1301 and inert gases showed multiplier effect. There were the optimized mixing ratios of the most effective agents. Flame-extinction temperatures were calculated for the n-heptane flames with the flame extinguishing concentrations of agents. The temperatures suggested that the chemical effect of halon 1301 was enhanced with decreasing the flame temperature by the addition of inert gases. The flame temperature and the concentration of halon 1301 determined strength of the multiplier effect of halon 1301 and inert gas.

Flame-extinguishing concentrations and peak concentrations of N2, Ar, CO2 and their mixtures for hydrocarbon fuels

Fire-extinguishing efficiency of inert gas mixtures was investigated by measuring flame-extinguishing concentrations and peak concentrations for hydrocarbon fuels, because new fire-extinguishing agents composed of inert gas mixtures have been developed as halon alternatives. The flame-extinguishing concentrations of nitrogen, argon, carbon dioxide and their mixtures for n-heptane were measured with the FRI glass cup burner. The peak concentrations of the agents for methane-air and propane-air mixtures were also measured with the tubular flame burner. Chemical equilibrium calculations showed that the adiabatic flame temperatures of the cup burner flames at the extinction condition were almost constant for all the agents. The adiabatic flame temperatures at the flammability limit of the tubular flame for each fuel were also independent of the inert gas agent if the mixtures had the same equivalence ratio. The flame-extinguishing concentrations of the inert gas mixtures were predicted by a simple equation averaging over the flame-extinguishing concentrations of all component gases weighted by mole fraction. The equation has the same form as Le Chatelier's law. For the flammability limits of the hydrocarbon-air mixtures, the same relation was also recognized in the effect of the mixed agents. The facts show clearly that this simple equation for the flame extinction concentrations is useful to estimate the fire suppression efficiency of any mixed agents of the inert gases. At the same time, it appears that the flame-extinguishing concentrations and the flammability limits reported in the paper are consistent.

96/04140 Influence of structure of polymetric fuels on the combustion behaviour of composite solid propellants

Suppression of methane/air and propane/air nonpremixed counterflow flames, and n-heptane and methanol cup burner flames by fluorinated hydrocarbons was investigated. Four fluorinated ethanes, 10 fluorinated propanes, four bromine- or iodine-containing halons, and the inert agents CF4, SF6, and N2 were tested in some or all of the flames. Laser Doppler velocimetry (LDV) determinations of peak velocity gradients in the oxidizer flow of the counterflow flames were found to be linearly correlated with the expression for global strain rate derived for plug flow boundary conditions. This correlation was used to estimate strain rate values at extinction. The bromine- or iodine-containing agents are more effective on a molar basis than the fluorinated propanes, followed by the fluorinated ethanes, and finally SF6, CF4, and N2. Agent effectiveness increases with the number of CF3 groups present in the agent molecular structure. Numerical investigations of the flame speed reduction of methane/air mixtures doped with either CHF2CHF2 or CF3CH2F predict that the latter is the better agent, in accord with experimental observations. Chemical contributions to suppression account for less than 35% of the total suppression offered by fluorinated hydrocarbons not containing bromine or iodine. At strain rates below 100 s−1, suppression effectiveness rankings in methane and propane counterflow flames are similar to those obtained in n-heptane and methanol cup burner flames. Methanol flames are more difficult to extinguish than the alkane flames investigated, particularly with the chemical agent CF3Br.

Extinction of counterfiow diffusion flames with halon replacements

Extinction of counter/low diffusion flames on liquid fuels was investigated, to confirm the superiority of the counterflow diffusion flame over the cup burner method for measuring flame extinguishing concentrations of fire suppressants, and to examine the fire suppression effects of halon replacements. The flame extinguishing concentration for the counterflow flame was less sensitive to the burner size than that for the cup burner method. Furthermore, the flow velocity of the fuel vapor had no change when the suppressant concentration in the oxidizer mixture of the counterflow diffusion flame was varied, whereas it changed remarkably in the case of the cup burner flame. The flame extinguishing concentrations of nitrogen, carbon dioxide, halon 1301 (CF3Br), and three kinds of hydrofluorocarbons (HFC) and perfluorocarbon (FC) for n-heptane or ethanol counterflow flames were measured at various strain rates. Adiabatic flame temperatures at the extinction concentrations were calculated using the flame extinguishing concentrations measured for counterflow flames, assuming various equivalence ratios. The results suggest that HFC-23 (CHF3) suppression exhibits a higher contribution to the chemical suppression effect than other HFC or FC.

Extinction of non-premixed methane-and propane-air counterflow flames inhibited with CF 4, CF 3H and CF 3Br

The extinction condition was studied for non-premixed counterflow flames of methane and propane impinging against an air stream with added amounts of CF 4 , CF 3 H, or CF 3 Br. Strain rates near extinction using laser Doppler velocimetry were determined for counterflow methane-air flames, with CF 4 and CF 3 H added to the air stream. The value obtained for the case of methane impinging against an air stream with no agent added, 400±25 s −1 , agrees with the experimental value reported in the literature. For both methane-and propane-air flames, increasing amounts of CF 4 , CF 3 H, or CF 3 Br in the air stream decrease the extinction oxidizer stream mass flow rate (or strain rate) monotonically until, at a given amount of agent, the extinction strain rate rapidly drops. If the molar percentage of agent in the air stream exceeds 2.5% for CF 3 Br and 11% for CF 4 or CF 3 H, non-premixed counterflow methane-air flames cannot be maintained. Counterflow propane-air flames cannot be maintained if agent concentrations in the air stream are greater than 2.7% for CF 3 Br, 11% for CF 3 H, and >14% for CF 4 . For a given amount of agent added to the air stream that does not exceed the limiting agent concentration, the extinction strain rate is comparable for CF 3 H or CF 4 addition in methane-air flames. CF 3 H is more effective than CF 4 in propane-air flames, similar to the reported extinction behavior in heptane-air cup burner studies. CF 3 Br is significantly more effective than CF 4 or CF 3 H in extinguishing methane-or propane-air flames. The net chemical effect of CF 3 H in the inhibition of non-premixed counterflow flames is more pronounced for propane-air flames than for methane-air flames. Explanations for this behavior are discussed briefly.

Scale effect of cup burner on flame-extinguishing concentrations

In an attempt to reduce the amount of chemical used in fire suppression testing of halon alternative agents, smaller cup burner systems than that of ISO were constructed, and the flame-extinguishing concentrations of Halon 1301 for three liquid fuels were measured. Reducing the cup diameter or the chimney diameter of the cup burner changed significantly not only the flame-extinguishing concentrations but also the flame behavior near extinction. Nevertheless, the reduced size cup burners with which the flame-extinguishing concentration was equal to that of the ISO cup burner were found. One cup burner can reduce the amount of extinguishing agent used in testing by 90%.