摘要:

AbstractThe chemical mechanisms for the action of flame retardants are often mentioned in the literature but the physical modes of action are seldom. Discussed. This article presents one way to quantify their efficiency. The technique is based on literature data for the physical and thermal properties of flams retardants for temperatures from 25°C up to 1000°C. The prolongation of the time to ignition by heat absorption by the retardant and the amount of inert gas evolved by the retardant are calculated at a given radiation for a material flame‐proofed with a given amount of the flame retardant. The ability to form an insulating surface layer is considered but not quantified. It is assumed that a medium density wood fibre building boards is treated with 2 kg of flame retardant per m2. The flame retardants included are borates, boric acid, phosphates and silicates. The board is assumed to be irradiated with an intensity of 15 k W m−2. Under these conditions an untreated board ignites after 6–7 min. The time to ignition is prolonged by 1–5 min through heat absorption by the different retardants, and the amount of inert gases evolved may be as high as 2.6 m3per m2board. The formation of an insulating surface layer is more difficult to quantify. The results confirm the importance of the physical modes of action of flame retardants and the technique could form the basis for evaluating materials in simulated fire s

ISSN:0308-0501    

DOI:10.1002/fam.810010302

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

摘要:

AbstractResults are presented for mass generation rates of major combustion products (CO2, CO, total hydrocarbons and smoke particulates) and heat release rates from samples of polymethylmethacrylate and polystyrene burning in normal air under varying magnitudes of externally applied radiant heat flux. In the experiments mass generation rates of products and convective heat release rates are measured and, from heat and mass balance, actual and radiative rate of heat release, as well as heat that is not released due to incompleteness of combustion, are calculated. From the data, 99% of the rate of the theoretical heat release for complete combustion can be accounted for. In some cases the experimentally derived heat release rate was less than half that predicted from mass loss rate (assuming complete combustion). This ‘combustion efficiency’ decreased strongly with increasing externally applied radiant flux, and was always much lower for polystrene than for polymethylmethacrylate. At the ‘deal’ condition, defined as a condition where heat losses have been compensated and where the mass burning rate of polystyrene is 1.44 times the rate for polymethylmethacrylate, polystyrene generates 6.60 times more CO, 7.83 times more smoke particulates, and the radiative rate of heat release is 1.75 times more than that of polymethylmetha

ISSN:0308-0501    

DOI:10.1002/fam.810010303

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

摘要:

AbstractAssesing the total potential fire hazard of modern interior surfacing of buildings requires a method which includes determination of smoke toxicity concurrently with fire and smoke production parameters. The Fire Propagation Box Test (British Standards Institution BS 476, Part 6) is a promising contender. It has been examined in the flaming mode as a method for evaluating smoke production concurrently with fire propagation indices for a range of surfacings, rather than resorting to a separate procedure by using fans with the same apparatus, as described in the former British Standards Institution Draft for relation to rate of burning the concurrent procedure is shown to be the more valied method.

ISSN:0308-0501    

DOI:10.1002/fam.810010304

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

摘要:

AbstractStress–strain behaviour of concrete at elevated temperatures is extremely complex and is not completely understood up to now. The creep properties of concrete at temperatures up to 300°C thus need to be determined, as well as the thermal stability of concrete during repeated cycles of heating and cooling. In this report the results of recent high temperature experiments with normal concrete specimens are presented. The main objectives of the tests were to investigate the dependence of strength and elasticity on temperature and to study the creep and deformation characteristics of concrete at temperatures up to 450°C. Transient creep data, i.e. data derived under transient temperature conditions, are compared with creep data which were measured at constant elevanted temperatures. The results suggest that transient creep values and steady state creep values in some cases may be of the same magnitude.The creep measurements appear to be in good agreement with data presented by other workers. However, the scatter in all data increases significantly with increasing temperature and differences of more than 100% can be observed. When loaded concrete specimens were cooled down to ambient temperature exptraordinarily large compressive strains can be observed. The experiments indicate clearly the considerable strain capacity of normal structural concrete can be used at temperatures higher than 100°C. In areas of high stress concentrations a tures. On the other hand, with respect to the whole structure it is necessary to limit the deformations. For a constant maximum temperature this can only be done by limiting the admissible stresses. The test results permit an initial estimation of maximum permissible stress and temperature va

ISSN:0308-0501    

DOI:10.1002/fam.810010305

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

摘要:

AbstractIt is important to be able to predict the rate of smoke and fire spread in buildings in order to optimize the design of escape routes and the siting of detectors and sprinklers. The available mathermatical procedures based on turbulence models require experimental guidance. This paper describes the measurement of some turbulence parameters in smoke and flame plumes moving under a ceiling. Time correlation techniques are applied to signals obtained from thermocouple and Langmuir probes. Space‐time correlations in the hot layer show similar trends to those in decaying isotropic turulence from wind tunnels but superimposed upon a coherent sine wave produced by vortex shedding at the fire. Data are also presented of the probability of chemical reaction at several locations in the hot laye

ISSN:0308-0501    

DOI:10.1002/fam.810010306

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

摘要:

AbstractA commercial chemiluminescent nitrogen oxides analyzer performed well in its nitric oxide mode when applied to the combustion products of polyurethane materials, but when test gases were passed through a thermal converter prior to measurement of nitrogen dioxide, serious, interferences was encountered from hydrogen cyanide and other nitrogen compounds.

ISSN:0308-0501    

DOI:10.1002/fam.810010307

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

ISSN:0308-0501    

DOI:10.1002/fam.810010309

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

ISSN:0308-0501    

DOI:10.1002/fam.810010310

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY

ISSN:0308-0501    

DOI:10.1002/fam.810010301

出版商:Heyden&Son Ltd.    

年代:1976

数据来源: WILEY