Cup Burner Method Research Articles

Evaluating the suppression effectiveness of hybrid nitrogen and water mist with a cup burner coflowing flame

SummaryThe suppression effectiveness of an intrinsically clean hybrid fire suppressant consisting of nitrogen and water mist was experimentally studied by a cup burner method with methane/air coflowing flame. A series of hybrid agents with different weight ratios of nitrogen and water mist (Sauter mean diameter: 12.6 μm) were tested and compared with nitrogen and water mist used alone. The minimum mass‐based extinction concentration (MEC) of neat nitrogen and water mist was measured as 32.1% and 15.2%, respectively. When combined, MEC of the hybrid agents fell between the limiting values of nitrogen and water mist used alone. An approximately linear relationship was shown for the suppression behavior of nitrogen and water mist in combination. The flow field of suppressants during the flame suppression process was studied by particle imaging velocimetry (PIV) technique. A small portion of water droplets near the flame front evaporated, which contributed to flame extinction by heat absorption and oxygen dilution. The remaining bulk mist was entrained vertically with the air flow, showing little effect on the flame base.

Investigation of the effect of dimethyl methylphosphonate (DMMP) on flame extinction limit of lithium-ion battery electrolyte solvents

An experimental and numerical study was conducted to quantify the flame retardant effects of different DMMP addition loadings on the flame extinction limits of four lithium-ion battery electrolyte solvents. The minimum extinguishing concentration (MEC) of CO2, which was measured using the cup-burner method, was applied to characterize the flame retardant effects of different DMMP loadings. Then, a model based on the perfectly stirred reactor concept was constructed to calculate the MEC and interpret the measurements established in the cup-burner test. A comparison was conducted between the measured and calculated MECs of N2 and a satisfactory agreement was obtained. Further investigation found that DMMP could significantly improve the extinction temperature by clearing the H radical, suppressing the reaction temperature and increasing the sensitivity of temperature to reaction rate constants, which caused the decrease in the flame extinction limit of solvents. The experimental results showed that DMMP has a certain saturation effect on reducing the flame extinction limits of solvents. For the four solvents, the sensibilities of the flame extinction limits to the DMMP additions were different, which were ranked in the order of diethyl carbonate > ethyl methyl carbonate > dimethyl carbonate > ethyl acetate.

Experimental study on the performance of transition metal ions modified zeolite particles in suppressing methane/air coflowing flame on cup burner

This study investigated the performance of three kinds of transition metal ions (Mn2+, Cu2+, and Zn2+) modified zeolite 4A particles in suppressing methane/air coflowing flames on cup burner. Ion-exchange method was employed to incorporate different amount of transition metal ions into parent zeolite 4A. Fire suppression effectiveness of zeolites containing varied molar percentage of metal ions was tested by cup-burner method. Results showed that transition metal ions modified zeolites outperformed the parent zeolite 4A with a ranking order of Mn2+ > Cu2+ > Zn2+. Performance of the zeolite particles was affected by the percentage of transition ions loaded, which dominated the number of active sites and Brunauer–Emmett–Teller surface area of the particles. Increasing molar percentage of metal ions loading increased the capacity to scavenge flame radicals, but decreased Brunauer–Emmett–Teller surface area of the particles. There existed an optimized molar percentage of transition metal ions loading where the best fire-suppressing effectiveness was exhibited.

Standardizing the Measurement of Minimum Extinguishing Concentrations of Gaseous Agents

The cup-burner test method has had a long history as a tool for measuring the minimum flame extinguishing concentrations (MEC) of gaseous fire-extinguishing agents for flammable and combustible liquid fuels. The pioneering work by Hirst and Booth (1977) set out the basic principles of the cup-burner and its use. Saso et al. (1993) reported on scale effects on MEC measurement. Preece et al. (2003) reported on parametric effects on MEC measurement. A number of investigators have provided determined values of MEC for a number of inert gas and fluorocarbon agents. See Dlugogorski et al. (1996); Saito et al. (1996); Moore et al. (1998); Sheinson et al. (1998). Takahashi et al. have reported on several investigations of flame extinguishment in the cup-burner including conducting a detailed computational fluid dynamic modeling including reaction kinetics and mass and heat transfer (2003); physical and chemical aspects of flame extinguishment (May 2005); and evaluation of flame extinguishment in low gravity (January 2005). Application of the cup-burner method has, in some instances, produced inconsistent results. MEC values reported by several investigators for the same inert gas agents have exhibited differences that are significant with respect to the way in which they are used (Senecal 2005). Thermochemical analysis and data obtained in a consistent manner suggested that there is a reasonable basis to expect highly consistent, and even predictable, MEC values for inert gas agents. It appeared that the likely source of measurement variation was due to procedural and mechanical differences in the conduct of the cup-burner test among various laboratories. A Task Group, appointed by the NFPA GFE-AAA technical committee on gaseous fire-extinguishing systems, revised the cup-burner test procedure including the specification of a standardized test apparatus. This article describes an inter-laboratory study conducted in 2006 to (1) determine consensus value benchmark minimum extinguishing concentrations (MEC) of an inert gas agent and a halocarbon agent; (2) evaluate the reproducibility of the revised test method; and (3) evaluate the day-to-day consistency (repeatability) of the test method. The results of an inter-laboratory (round robin) study have established benchmark MEC values for nitrogen and HFC-227ea with excellent reproducibility. The results show that MEC values reported by most laboratories were in very good agreement, i.e., exhibited good reproducibility based on averages of three replicate determinations on different days. Analysis of the replicate data revealed a variable degree of repeatability, suggesting that a laboratory will need to review key procedural details in some cases.

Fire-Extinguishing Effectiveness of 1-Bromo-3,3,3-Trifluoropropene/Inert Gaseous Mixture Evaluated by Cup Burner Method

1-bromo-3,3,3-trifluoropropene with low extinguishing concentration has been identified, but it has high boiling points and is not suitable replacements for halon 1301. However, mixtures of 1-bromo-3,3,3-trifluoropropene 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 concentration of the 1-bromo-3,3,3-trifluoropropene/inert gas mixtures. In this study, a method based on cup-burner was used to estimate the extinguishing concentration of 1-bromo-3,3,3-trifluoropropene/inert gas mixtures. A mechanism for mixing 1-bromo-3,3,3-trifluoropropene with inert gas before applying to fire was proposed. The results show that addition of small amount of 1-bromo-3,3,3-trifluoropropene in inert gas reduces the extinguishing concentration of inert gas considerably, and 1-bromo-3,3,3-trifluoropropene/inert gas mixture suppressant shows strong synergistic interactions at low mole concentration of 1-bromo-3,3,3-trifluoropropene.

Flame extinguishing in the cup-burner by inert gases

National and international standards on gaseous fire extinguishing systems specify the minimum design concentrations of gaseous agents for flammable liquid hazards based on extinguishing concentrations determined by the cup-burner method. Extinguishing concentration values, X G, reported in standards documents do not correlate as well as expected with heat capacity, the underlying figure of merit for inert gas agents, a result that is likely due to inconsistent application of the test method. In this paper an explicit relation is developed for inert gas extinguishing concentration in terms of heat capacity and fuel properties. Equilibrium stoichiometric combustion at the fuel–air interface is assumed. A unified set of extinguishing concentration data for six inert gas agents is used to validate the model. For n-heptane flames the characteristic extinction limit temperature, T Ex, was found to be essentially the same for each inert gas agent, though T Ex may depend on details of the test apparatus and procedure, variations of which may account for the observed inconsistencies in data submitted by different laboratories. The measured X G for CO 2 was ∼5% less than expected based on heat capacity effects alone, a result qualitatively consistent with elevated heat loss due to radiation by CO 2. The results of this work are expected to be useful in eventually harmonizing data used fire protection standards.

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.

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.

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.

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.