| 1. |
- Andersson, Berit, et al.
(författare)
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Simulated Fires in Substances of Pesticide Type
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to characterise fires in chemical warehouses, 38 medium scale experiments have been conducted. The experiments were performed in a 0.66m3 combustion chamber. On-line measurements were made of combustion gases (CO2, CO, HC and NOx), mass loss, smoke, temperatures, external radiation and phi-values. Intermittently gas and soot samples were collected and analysed for content of organic compounds and amount of soot produced. Main variables during the experiments were external radiation, fire diameter, opening configuration and ventilation condition. The medium scale was chosen in order to give a test method which is more convenient to work with, less expensive than full-scale experiments and still rather well simulates the conditions in a real fire.
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| 2. |
- Frantzich, Håkan, et al.
(författare)
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Brand och explosion
- 2003
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Ingår i: Risker i tekniska system. - 9144026641 ; , s. 275-299
-
Bokkapitel (populärvet., debatt m.m.)
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| 3. |
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| 4. |
- Andersson, Berit, et al.
(författare)
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Combustion of Chemical Substances and the Impact on the Environment of the Fire Products: 1/3 Scale Room Furnace Experiments
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes the results obtained from fire tests in a 1/3-scale room. The aim of the study was to investigate how changes in external radiation and oxygen supply affect the production of smoke and toxic gases. The ventilation was varied to simulate under- and well-ventilated fires. The thermal exposure to the materials was varied to simulate fires of different sizes. Fifty-nine tests were performed, with polystyrene, FR polystyrene, polypropylene, nylon and PVC. Measurements were made of the contents of O2, CO2, CO, NOx, and HC in the exhaust gases. The impact of external radiation was mainly to increase the pyrolysis rate, and thus the rate of heat release, and to drive the fire into under-ventilation. The degree of ventilation proved to have the greatest impact on the combustion efficiency. The smoke production was almost constant for polypropylene and nylon. The CO production appeared to be the most complex of the parameters to describe, and the expected increase in CO yield at low yields of CO2 could not be seen. The generation of NOx was low for the two substances without chemically bound nitrogen, but for nylon, the generation was significant. The production of low molecular weight HC was essentially constant for all three materials. Almost all the carbon was recovered in wellventilated fires, but at under-ventilated conditions, only 30% of the carbon from the he1 was detected. The toxic potency of the exhaust gases was estimated using the N-gas model, and proved to be relatively low. Lack of oxygen and the production of carbon oxide had the greatest impact on the toxicity for polystyrene and polypropylene, while NO, represented the main part for nylon. The survival fraction and the decomposition products from the original materials are not considered in the model. It can therefore not be assumed that the model reflects all aspects of the toxicity problem.
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| 5. |
- Andersson, Berit, et al.
(författare)
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Combustion products generated by hetero-organic fuels on four different fire test scales
- 2005
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 40:5, s. 439-465
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Tidskriftsartikel (refereegranskat)abstract
- The scaling of results from combustion experiments with four organic substances containing heteroatoms, carried out on four different scales, is discussed. The scales ranged from the micro-scale, using about 2 x 10(-3) kg of the substances, to large scale using about 50 kg of the substances. The content of O-2, CO, CO2, NOx, HCl, HCN and SO2 in the combustion gases were determined with special attention to the survival fractions of the tested substances and the amount of unburned hydrocarbons. The global equivalence ratio (GER) was used to describe the ventilation conditions during the experiments. The conditions were adjusted to range from under- to well-ventilated situations. It was found that the GER is not the only parameter that influences the production of combustion gases. Other parameters such as temperature and residence time also seem to be important in explaining the results. The experiments were performed as a part of the TOXFIRE project within the EC Environment programme.
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| 6. |
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| 7. |
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| 8. |
- Andersson, Berit, et al.
(författare)
-
Naturgas Säkerhetsnivå Riskanalys
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport har tillkommit på uppdrag av NUTEK och avser att belysa riskerna med distribution och industriell användning av naturgas. Tidigare har en rapport avseende naturgasinstallationer i hemmen utgetts [1,2]. Rapporten inleds med en allmän diskussion om risker. Vidare tas frågan om lagstiftning, tillsyn, kontroll och utbildning för naturgasanvändning i olika lander upp. Dessutom har en retrospektiv sökning efter statistik om naturgasolyckor samt incidenter gjorts. En kort genomgång av hur man beräknar konsekvenser av naturgasutsläpp görs också.
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| 9. |
- Andersson, Petra, et al.
(författare)
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An instrument for determining the total water content in air when extinguishing fires
- 1999
-
Ingår i: Fire and Materials. - 1099-1018. ; 23:4, s. 187-192
-
Tidskriftsartikel (refereegranskat)abstract
- n instrument suitable for measuring the total water content both as small liquid droplets and as vapour in the air, in water mist total flooding extinguishing tests, is presented. The instrument consists of a heater and a Vaisala humidity meter. The Vaisala humidity meter is capable of measuring relative humidity at temperatures up to 180°C. The instrument has a measuring range of 0-600g/m3, a sample rate of 1 L/min, a time constant of 5-10 s and an accuracy of ±40 g/m3. Accurate results are obtained when used outside the direct spray from a nozzle. If the instrument is placed in the spray the total water content can be either over- or underdetermined, depending on which part of the instrument faces the spray.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Andersson, Petra, et al.
(författare)
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Heat Sensing Manikin Test Probe
- 2000
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Ingår i: Fire and Materials. - 1099-1018. ; 24:4, s. 195-199
-
Tidskriftsartikel (refereegranskat)abstract
- A manikin test probe has been developed to simulate the thermal behaviour of human skin when exposed to thermal conditions likely to occur in fires. The threshold for second-degree burn injuries is evaluated from the temperature readings using a damage integral. The probe has been exposed to different radiation fluxes and the calculated damage criterion for second-degree burn injuries is in agreement with data from the literature on human skin and pig skin. Probes mounted on a manikin have been used to assess how the extent of burn injuries develop as a function of time on a fully dressed pilot inside a military aeroplane surrounded by a large pool fire. In another scenario burn injuries for humans inside a fire room are assessed when a super-heated water mist extinguishing system is activated.
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| 14. |
- Andersson, Petra, et al.
(författare)
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Heat sensing manikin test probe
- 2000
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Ingår i: Fire and Materials. - 0308-0501 .- 1099-1018. ; 24, s. 195-199
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 15. |
- Andersson, Petra, et al.
(författare)
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Limitations of Water Mist as a Total Flooding Agent
- 1998
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Ingår i: Journal of Fire Protection Engineering. - : SAGE Publications. - 1042-3915. ; 9:4, s. 31-50
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Tidskriftsartikel (refereegranskat)abstract
- The limitations of water mist in acting as a total flooding agent are discussed in this paper. The paper focuses on water mist consisting of droplets 1-100 µm in diameter. Water mists are very efficient as an extinguishing media if they are present in the flame. There are, however, several problems associated with introducing the water mist into the flame: the spray reaches only a short distance; small water droplets have a very short lifetime; droplets coagulate into larger droplets; large droplets hit obstacles such as walls and therefore have difficulties in being dispersed throughout the protected volume.
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| 16. |
- Andersson, Petra, et al.
(författare)
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Small scale experiments and theoretical aspects of flame extinguishment with water mist
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The present study focuses on extinction of flames with water mist where surface cooling effects are neglected i.e. water mist as a total flooding system where the direct spray cannot reach and cool all burning items in the protected volume. The study includes a survey of the production and properties of water mist such as different types of nozzles and means to describe droplet size distribution. Properties of jets and sprays are discussed as well as water droplet movement, fall and evaporation. Three different series of experiments were conducted with different hydraulic atomising nozzles. In the first series, droplet size distribution and water spray distribution measurements for the nozzles were conducted. The measurements showed that the droplet size distribution ranged from a Sauter Mean Diameter of approximately 35 - 85 µm, all dependent on the water pressure and the configuration of nozzles. The measurements show that considerably larger droplets are formed when individual nozzles are placed together. This can be explained by a coalescence effect when droplets from the sprays of the nozzles collide. The second series of experiments were done using a tubular propane gas bumer where water and propane were mixed prior to reaching the burner outlet. Based on the tests, the specific amount of extinguishing medium required (Required Extinguishing Medium Portion, REMP = m, / m, i.e. the ratio of the agent quantity to fuel quantity consumed) is given as a quantitative measure of the efficiency of the agent. The lower the REMP value, the more efficient the agent. The water pressure ranged between 40 and 80 bar which provided for droplet sizes with a Sauter Mean Diameter in the order of 35 pm. The results show that the amount of water needed for extinguishment by weight is between 1.2 - 2,2 times the amount of propane gas. The decrease in droplet sizes decreased the amount of water needed. Another observation was that the heat release rate of the fire is not affected until extinction occurs. A REMP-value of 1,2 - 2,2 corresponds to a water content of 100 – 200 g/m3 protected volume which is in agreement with theoretical values. Finally, a series of tests were conducted in a 113 scale room using a propane gas fire. Parameters such as location of the fire, the location of the nozzle, water flow rate and the size of the room opening were varied. In these tests the water content needed was in close agreement with the values obtained from the REh4P experiments and the theoretical values. These tests also highlighted the problem of delivering the droplets to the fire. To achieve "total flooding" in an actual situation, nozzles covering the complete protected compartment, with additional nozzles under obstructions would be needed. To make droplets follow the air flows inside a room and behave more like a gaseous total flooding agent, requires droplets of a size in the order of 1 - 20 µm.
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| 17. |
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| 18. |
- Blomqvist, Per, et al.
(författare)
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An experimental study of spontaneous ignition in storages of wood pellets
- 2007
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Ingår i: 10th International Conference - Fire and Materials 2007.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This article focuses on experimental studies of self-heating characteristics of wood pellets. Controlled experiments have been conducted in physical scales from 1 dm3 to 4 m3 with wood pellets. Basket tests have been conducted according to the "crossing-point method" to derive kinetic data on the exothermic reactions responsible for self-heating and eventually spontaneous ignition. The kinetic data was used in the planning of the large-scale experiments for predictions of approximate critical temperatures. The experiments in the 1 m3 scale were set-up basically as an enlargement of the basket tests to obtain validation experiments with controlled boundary conditions in a reasonable large scale. Several experiments were conducted and spontaneous ignition was seen in the centre of the pellet bulk at an ambient temperature of 115C. The close to real-scale experiments with 4 m3 wood pellets filled in a 6 m high silo were not strictly self heating experiments, instead a core shaped heating element was allowed to initiate the pyrolysis in the pellets. Heat and gas production and transportation from the growing pyrolysis zone were mapped with a large number of measurement points in the pellets bulk and in the top of the silo. The experimental work conducted gave kinetic data on the exothermic reactions in wood pellets, insight in self heating processes, a link between different experimental scales and knowledge regarding possibilities for detection of fires in storages of wood pellets.
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| 19. |
- Blomqvist, Per, et al.
(författare)
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Fires in storages of biofuels
- 2007
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Ingår i: Fire and Materials 2007 Proceedings.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 20. |
- Bohgard, Mats, et al.
(författare)
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Arbetsmiljö vid termisk ogräsbekämpning
- 1988
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten behandlar arbetsmiljön vid termisk ogräsbekämpning. Metoden innebär att ogräset hettas upp med hjälp av gaslågor. Både stora fordonsburna och mindre handdrivna används. Det som från arbetsmiljösynpunkt är speciellt med metoden är de risker som är förknippade med gasolanvändningen. De allvarligaste problemen med de aggregat som studerats har varit heta och oskyddade plåtar, heta avgaser och brister i komponentval när det gäller slangar och kopplingar. I rapporten ges anvisningar om åtgärder för att minska riskerna avseende komponentval, säkerhetsanordningar och utbildning. Bland myndighetskrav på utrustning kan nämnas att leverentatörer ska lämna säkerhetsanvisningar på svenska samt att arbetet inte får utföras av minderåriga. Den psykosoicala miljön har också undersökts. De operatörer som intervjuats har upplevt arbetet positivt.
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| 21. |
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| 22. |
- Göransson, Ulf, et al.
(författare)
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Numerical and experimental investigation of flame spread over a PMMA surface
- 2004
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Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- The objective of this study is the experimental and numerical investigation of flame spread over a PMMA surface. A series of upward flame spread tests were carried out in a cylindrical combustion room, with measurements made for gas velocity, surface temperature and surface heat fluxes. A CFD based flame spread model was then used for the simulation of the experiment. This model consists of a four-equation turbulence model, an eddy-break-up (EBU) combustion model, a discrete transfer (DT) radiation model, a statistical narrow band (SNB) gas model, a soot model, and a pyrolysis model for non-charring solids. Comparison was made between the numerical predictions and the experimental data. A reasonable qualitative agreement was found between two sets of data.
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| 23. |
- Hertz, H.M., et al.
(författare)
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High voltage measurement system based on a capacitively coupled Pockels cell
- 1987
-
Ingår i: Proc. SPIE - Int. Soc. Opt. Eng. (USA). ; 701, s. 8-226
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A fiber-optical system for measurements of fast high voltage pulses has been developed. The system is based on capacitively coupled Pockels cell voltage sensor and features excellent rejection of electrical interference, large bandwidth and practically unlimited voltage range. The authors describe the principle of operation and give a preliminary discussion of the performance of the measurement system
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| 24. |
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| 25. |
- Holmstedt, Göran, et al.
(författare)
-
Detector environment and detector response : a survey
- 1987
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 1. The survey has mainly concentrated on the following items: the false alarm problem, the problem of the fire not being detected due to the fact that pre-fire heating and ventilation dominate flow inside the compartment, a description of detector sensitivity to fire signatures. engineering design methods for the siting of detectors. 2. The statistical as well as practical experience suggests that alarm systems in Sweden, follow international trends regarding rates of false alarms. 3. For existing systems, especially the older ones, introduction of a proper alarm organisation, regular training of the technical maintenance staff and/or desensitization may be appropriate measures to reduce the false alarm rate. 4. Analysis shows that desensitization of existing systems must be done with care so life hazard is still kept under control. 5. In addition to the remedies mentioned under point 3 it might be effective to revise the siting standard rules in RUS 110 in the light of the information obtained for example in the Norwegian investigation. 6. A revision of RUS 110 should also be based on scaled down physical modelling and the use of numerical modelling (field modelling) in order to investigate local flow field characteristics: the influence of beamed ceilings, ventilation in and outflow. a thermally stratified pre-fire atmosphere, etc. 7. In order to take consideration of various fire developments rates and varying ceiling heights, standard siting distance should be calculated according to the design model described in NFPA 72E Appendix C for heat detectors. 8. For smoke detectors, a more rational use of the information obtained in the EN54/9 sensitivity test standard fires should be investigated. 9. Point 3 mentioned existing systems. For new and future systems the gradual improvement in software control (alarm verification procedures. automatic compensation for regular variation in ambient conditions, automatic change of sensitivity to compensate for the gradual accumulation of dust and dirt, filtering of electronic signal spikes, checking of electric circuit integrity etc) is thought to dramatically reduce false alarm rates. 10. Efficient pattern-recognition algorithms for separating fire process environments from the aerosols produced by welding, trucks exhaust, smoking etc may be hard to produce: the aerosol characteristics are too much alike. Algorithms based on use of data from a group of sensors ("group decision") should be more reliable but may be too complex. In theory, if sensor response to monodisperse aerosols is known and with standard test fire aerosol characteristics experimentally measured, sensor output during the standard test fires should be easily calculable and a first check obtained on the discrimatory capability of pattern recognition algorithms. No information of this kind has been found.
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| 26. |
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| 27. |
- Holmstedt, Göran, et al.
(författare)
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Determination of uncertainty of different CFD codes by means of comparison with experimental fire scenarios
- 2009
-
Ingår i: Conference Proceedings - Fire and Materials 2009, 11th International Conference and Exhibition.
-
Konferensbidrag (refereegranskat)abstract
- This article will summarise the evaluation of four CFD software codes (CFX, FDS4, SMAFS and SOFIE). Evaluation was performed by means of comparing the simulation data with experimental scenarios. The scenarios were chosen to represent scenarios frequently assessed using fire safety design based on performance. The greatest difficulty during validation of CFD-codes is to find well documented relevant experiments. It is true that many large scale experiments including smoke spread have been published but many of them are not described sufficiently and are therefore impossible to use for validation. It is very unusual that data on reproducibility and repeatability is available. After an extensive discussion between the participants in the project five scenarios were chosen. Scenarios 1A (large room with vents), and scenarios 1B1 and 1B2 (corridor with vents) were well documented experiments (repeatability) with ceiling vents and ceiling jets performed earlier at SP in Boras. Scenario 2 is a tunnel fire taken from an experimental study in Boston, US. Scenario 3 is an atrium fire taken from an experimental study in Japan. Lack of well documented fires in retail premises lead us to perform a series of tests in 1/2 scale, 4.1 and 4.2 at SP in Boras. Scenario 5 is an experimental study from Australia including smoke spread from a fire room to an adjacent corridor and a room. The conditions for the simulations included information about the scenarios given above. No information about experimental results was available until the results from the simulations had been sent in to the project manager. The intention was to imitate the working conditions for a consultant as far as possible when using a CFD-simulation to estimate fire safety. In this manner the simulations are dependent on many factors such as the CFD-code used, judgement of input data of the scenarios done by the operator, operator skill etc. The results from the evaluation of the CFD codes showed that the simulation results generally were a good description of the experimental fires studied, but that limitations and specific properties of the different codes, together with the operator factor, can strongly influence the results. The detailed results of all comparisons are given in the final report of the project. It was not possible to include these detailed evaluations in this conference paper but these results are available in the main report as well as in future scientific articles.
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Holmstedt, Göran
(författare)
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Rate of heat release measurements with the Swedish box test
- 1984
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Ingår i: Fire and Materials. - : Wiley. - 1099-1018 .- 0308-0501. ; 8:1, s. 20-27
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract The Swedisn box apparatus was modified to include an oxygen analysis of the exhaust gases to be compared with the conventional exhaust gas temperature measurement. A slow-burning material shows good correlation between the temperature measurement and the rate of heat release. A fast-burning material, however, consumes all the available oxygen, and the temperature measurement becomes a measure of only the thermal properties of the material.
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| 34. |
- Holmstedt, Göran, et al.
(författare)
-
Riskanalys av två ytbehandlingsindustrier i Jönköpings län
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Riskanalysen har genomförts av institutionen för brandteknik, Lunds tekniska högskola, i samarbete med räddningstjänsten i Jönköping. Riskanalysen gjordes på uppdrag av Statens räddningsverk och ingår som en del i deras projekt om kommunal riskhantering. De inblandade har från brandteknik varit Göran Holmstedt (projektledare), och Jan-Erik Öst. Från räddningstjänsten i Jönköping har Clas Lövgren deltagit. Syftet med riskanalysen har varit att visa på de konsekvenser för liv, miljö och egendom som några olika tänkta olyckor, såväl vid brand som kemikalieutflöde och/eller en kombination av dessa kan medföra.
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| 35. |
- Holmstedt, Göran, et al.
(författare)
-
Risker för brand och explosion efter vätskespill i dragskåp
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Försöken med förångning från vätskespill av aceton, dietyleter, etanol och metyletylketon och fördelning av brännbara ångor i dragskåp utförda med en inloppshastighet av ca 0.5 m/s visade att: mängden förångad vätska efter spill av olika vätskor vid olika initialtemperaturer kan förutsägas med god noggrannhet med befintliga dataprogram. Vid ett spill stannar den tunga ångan kvar i den nedre delen av dragskåpet (≤ 10cm) och sugs nästan fullständigt ut genom den nedre luftspalten i dragskåpet. Vätskespill, som sprider sig över stora delar av dragskåpets bottenytan, ger upphov till så höga lokala gaskoncentrationer att 25% av den undre brännsbarhetsgränsen överskrids i den smala luftspalten i dragskåpets baksida samt i ventilationskanalen omedebart efter dragskåpet även vid mycket stor ventilation. Genom att minska den yta spillet upptar, speciellt i djupled, kan de lokala gaskoncentrationerna avsevärt reduceras. Inne i dragskåpet föreligger ingen risk för gaskoncentrationer av tunga gaser som överstiger 25% av den undre brännbarhetsgränsen på höjder över 10-20 cm från dragskåpets yta. Försök med brand i dragskåp efter spill av aceton, etanol och heptan i dragskåpet visade att: det undersökta dragskåpet har ett gott brandmotstånd och klarar några minuters brand i vätskespill. En brand i vätskespill blir nästan omedelbart ventilationskontrollerad. Vid stor ventilation sugs nästan alla lågor ut genom den nedre spalten i dragskåpets underkant. Om branden tillåts fortgå någon minut med stor ventilation erhålls avsevärda skador på ventilationssystemet. Stängd ventilation ger det långsammaste brandförloppet. Värmedetektorer (grade 2 och 3 med utlösningstemperatur 58-60ºC), placerade på dragskåpets bakre vertikala vägg ca 1 m från bottenplattan, utlöste vid samtliga försök inom 10s från brandens start. Samma värmedetektorer, placerade i ventilationskanalen 2m från dragskåpet utlöste inom 20s när ventilationen vae 100m³/h per löpmeter samt inom några få sekunder när ventilationen var 600 m³/h per löpmeter. Vattensprinkling (sprinklern monterad i dragskåpets tak) med 10-20 l/m² per minut är ett dåligt släckalternativ. Vid sprinkling fortgår branden ofta en minut efter det att sprinklern utlösts. Det föreligger även risk att branden p.g.a. sprinklingen sprids från dragskåpet till golvet utanför dragskåpet. Koldioxid påförd med handbrandsläckare vid dragskåpsluckans nedre del släcker branden inom några få sekunder. Den använda koldioxidmängden för släckning var mindre än ett kilo. Två explosionsförsök med ett dragskåp visade att: dragskåpet klarar en explosion efter en fördröjd antändning av ett spill av 1 liter dietyleter utan att glaser i dragskåpet spricker. Tryckavlastningen sker dels snett nedåt genom dragskåpsluckans öppning (5cm) och dels uppåt genom den lucka (0.64 x 0.2 m) som finns för ljusintag i dragskåpets tak. Luckan var vid försöken täckt med en 10mm tjock aluminiumplåt som lagts fritt över intaget.
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| 36. |
- Holmstedt, Göran, et al.
(författare)
-
Risker vid eldning med naturgas i värmeanläggningar för bostadshus: Etapp 1: beskrivning av naturgas och värme- anläggningar
- 1989
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hur naturgas bildas är ännu ej definitivt klarlagt. Den etablerade och allmänt accepterade uppfattningen är att de största gasfyndigheterna bildades under samma tidsperiod och på ungefär samma sätt som oljan – d.v.s. genom förkolning av djur- och växtorganismer för 300-400 miljoner år sedan. Det finns dock naturgas som inte är äldre än 100-150 miljoner år, t.ex. den danska Nordsjögasen. Under senare år har emellertid nya teorier framförts som anger att flera olika ursprung skulle kunna vara möjliga, bl.a. från jordmanteln kommande icke biologisk naturgas – s.k. djupgas.
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| 37. |
- Holmstedt, Göran, et al.
(författare)
-
Risker vid naturgasuppvärmning i bostäder : Etapp 2: brandrisker och behovsbedömning av kontrollåtgärder
- 1989
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Naturgas är ett rent bränsle som endast innehåller små mängder föroreningar, [1]. Jämfört med kol är föekomsten av föroreningar i naturgas vanligen 1000 ggr mindre. Man får därför inga problem med svaveldioxid, tungmetaller, klorerade föroreningar etc i avgaserna. Vid normal drift bildas mycket lite sot och de huvudsakliga förbränningsprodukterna är vatten och koldioxid. Vatten ställer normalt inte till några problem om avgaskanalen är rätt utformad. Koldioxid betraktas som en miljögas men utsläppet från naturgas är per energienhet lägre än för andra bränslen, Tabell 1.1.
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| 38. |
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| 39. |
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| 40. |
- Holmstedt, Göran, et al.
(författare)
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Spray fire tests with hydraulic fluids
- 1986
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Ingår i: Fire Safety Science, Proceedings of the First International Symposium.. ; , s. 869-879
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two test series simulating the hazards associated with the accidental release of hydraulic fluid near a source of ignition have been carried out with six hydraulic fluids; mineral oil, organic ester, phosphate ester, water in oil emulsion and two polyglycols in water solution. The flame length, temperature and radiation and the auto-ignition temperature were measured. The correlation between the two test series regarding rates of heat release between 1 and 20 MW was very good. As a result a test method is proposed.
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| 41. |
- Holmstedt, Göran
(författare)
-
The upper limit of flammability of hydrogen in air, oxygen, and oxygen-inert mixtures at elevated pressures
- 1971
-
Ingår i: Combustion and Flame. - 0010-2180. ; 17:3, s. 295-301
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Tidskriftsartikel (refereegranskat)abstract
- The upper limit of flammability of hydrogen in air, oxygen, oxygen-helium, oxygen-neon, oxygen-argon and oxygen-carbon dioxide mixtures was measured at room temperature and pressures between 0.97 and 29 atm in two cylindrical bombs with volumes of 1.5 and 5.2 liters. The limit in ternary mixtures was determined in 20%, 40%, 60% and 80% helium, 20% neon and argon and 10% carbon dioxide concentrations. The maximum safe percentage of oxygen in a hydrogen-oxygen-helium mixture was calculated for pressures between 0.97 and 29 atm.
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| 42. |
- Holmstedt, Göran, et al.
(författare)
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Underventilerad brand
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Combustion of hydrocarbons in under-ventilated conditions has been studied experimentally and simulated with the CFD-code SOFIE. This report covers the experimental study in a 1/3 scale model of the ISO room corner test (ISO) 9705). The CFD-simulation part of the project has been published earlier in a SP-Report 1996:41 “CFD Modelling if under-ventilated Fires” by Heimo Touvinen and presented at the Second International Seminar on Fire-and Explosion hazard of Substances and venting of Deflagrations, Moscow 1997 and is published in the proceedings of the conference. In these experiments heptane was burnt in a 1/3 scale room model. The global equivalence ratio (GER) was changed during the experiments from a low value, (well ventilated fire) up to 1.8. At higher equivalence ratios the fire got unstable with violent fluctuations and flames now and then emerging out of the room. The following quantities were measured as a function of time in the experiments: Inside the room; Gas temperatures at eight levels (vertical array) in the corner of the room; Surface temperatures at six positions (three on the walls and three on the ceiling); Weight of the liquid fuel. In the doorway; Gas temperatures at seven levels (vertical array) in the centre of the doorway; Gas concentrations in the doorway (CO, CO2,) Global equivalence ratio in the doorway (Phi-meter). In the exhaust duct; Gas concentration(CO, CO2, O2, and HC); Light attenuation due to smoke; Pressure drop from a bi-directional probe mounted in the centre of the duct; Gas temperature in the centre of the duct. The following quantities has been derived from the measurement: Mass loss rate of fuel; Mass flow in the exhaust duct; Global equivalence ratio; Rate of heat release; Yields of CO, CO2, HC and soot at different equivalence ratios up to 1.8. The report includes three appendix, Appendix A (calibration procedures) Appendix B (derived variables as a function of time) and Appendix C 1-2 (raw data files of the experiments).
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| 43. |
- Holmstedt, Göran, et al.
(författare)
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University training of senior fire brigade officers. The new approach in Sweden
- 1989
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 15:1, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden a fundamental development has recently taken place in the training of future senior fire brigade officers. There are two main changes: the training period has been substantially increased and the theoretical part upgraded to university curriculum level with final requirements corresponding to a university undergraduate degree. The new educational system reflects the changing and expanding role of fire brigades and the need for a professionally improved leadership. To put the new training system into a proper context, the varied and dissimilar responsibilities of a Swedish fire brigade officer should be touched upon. Four main sectors are identified: business administration, fire prevention, training of employed staff and rescue service operations. The main structure of the training system and the university curriculum are discussed.
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| 44. |
- Holmstedt, Göran, et al.
(författare)
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Validation of CFD codes
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Use of CFD (computional fluid dynamics) softwarepackages within fire performance based engineeringand risk assessment is increasing substantially.An important part in the process is thequality assurance. For this reason the SwedishRescue Services Agency (SRV) sponsored aunique research project. Within the project differentcodes for smoke spread and evacuationhave been evaluated. This poster will focus onthe evaluation of four CFD software codes.
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| 45. |
- Husted, Bjarne, et al.
(författare)
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Comparison of PIV and PDA droplet velocity measurement techniques on two high-pressure water mist nozzles
- 2009
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Ingår i: Fire Safety Journal. - : Elsevier BV. - 0379-7112. ; 44:8, s. 1030-1045
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Tidskriftsartikel (refereegranskat)abstract
- The need for reliable measurement of droplet velocities and droplet size has increased with the more widespread use of water mist systems. Two optical measuring techniques have been investigated, Particle Image Velocimetry (PIV) and phase Doppler anemometry (PDA). Measurements have been performed on two high-pressure nozzles, a hollow cone nozzle and a full cone nozzle. Both methods performed well close to the nozzle and further away from the nozzle. In the intermediate region the results obtained with PIV are biased against the larger droplets. The two methods complement each other, PIV giving the instantaneous velocity field and PDA giving both the droplet velocity and droplet size at a point. The measurement indicates that higher throw length can be archived with a full cone nozzle compared to the hollow cone nozzle, if both nozzles have the same cone angle and flow rate.
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| 46. |
- Husted, Bjarne, et al.
(författare)
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Influence of Draft Curtains on Sprinkler Activation - Comparison of Three Different Models
- 2008
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Ingår i: Journal of Fire Protection Engineering. - : SAGE Publications. - 1042-3915. ; 18:1, s. 29-54
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates the importance of using draft curtains to obtain faster sprinkler activation with three different models-two computational fluid dynamics (CFD) models (CFX 4.4 and fire dynamics simulator (FDS) 4.07) and a zone model (Argos) containing a ceiling-jet formula - for an actual scenario in an entertainment center in Denmark. It is found that a draft curtain has some effect on sprinkler activation, reducing activation time from 8% to 15%, depending on the model implemented. The positions of the sprinklers with in the vertical computational grid of the CFD simulations have a greater influence on the activation of the sprinkler, where FDS is more sensitive than CFX. It is confirmed that heat transfer from the ceiling jet to the ceiling has little influence on the results. The zone model with a ceiling-jet formula gives 10—20% slower sprinkler activation than the CFD results when the sprinkler is close to the ceiling, but is still considered very useful in view of the faster calculation time.
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| 47. |
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| 48. |
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| 49. |
- Karlsson, Björn, et al.
(författare)
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Flame Sizes in a Small Scale Stack: Pilot Experiments
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For the last many decades industry and insurance companies have been interested in protecting high racked goods from rapid fire growth. This has mainly been done by installing sprinklers of various types and designs in order to either extinguish the fire or control it. The efficiency of such protection measures is, however, very much dependant on the geometry of the stacks, their height, floor area, the flue spacing, etc. and the flammable characteristics of the stored goods. A research project was initiated by the Swedish Fire Research Board (BRANDFORSK) to throw some light on the aforementioned geometric aspects of the problem. The main part of the project is to be carried out at the Swedish National Testing and Research Institute (SP) but a pilot study was initiated at Lund University, with some participation from scientists at SP. The work carried out at Lund University consisted of two parts. Firstly, Thomas [l] carried out a litterature survey of earlier experiments and summarized the main findings. Secondly, some experiments were made on reduced scale to examine the effect of the geometry of a pile of inert goods on the flames from a burner. This report describes the work carried out in this second part of the pilot study.
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| 50. |
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