A zone model for the prediction of thermal and chemical effects of a pool fire in a forced ventilated enclosure

Zone models have been developed since the early 60s for the prediction of fire parameters such as smoke temperature, smoke filling and movement in multi-compartment buildings. Unfortunately, one major difficulty in current zone models is that heat and chemical species release rates in relation with a given fire source term are usually to be provided as input data. A new zone model for prediction of thermal and chemical effects of pool fire in a forced ventilated enclosure has been developed

Controlled atmosphere bench-scale calorimetry revisited

International audienceThe standard Cone Calorimeter has been designed with an "open configuration", allowing for testing of specimens through use of freely driven room air for combustion. For testing specimens in oxygen depleted atmospheres or in fuel rich combustion a modified apparatus working under controlled atmosphere can be used. To our Knowledge there is very few publications describing the use of such modified cone calorimeters and providing data regarding the effect of ventilation on the fire properties. In the open literature it was reported end of the 1990's that substantial burning can occurred outside the test chamber when such a device is used, the amount of oxygen available to combustion exceeding the amount that was fed to the combustion chamber. In such a case (leading to post-buming outside the test chamber), it has been proposed to correct the experimental data by replacing the oxygen mass feeding rate by the actual rate of oxygen consumption. This paper analyses the proposed correction, and suggests that this might not be fully satisfactory by comparison to data obtained in another bench scale calorimeter with controlled atmosphere. The capacity of a Cone Calorimeter fitted with a controlled atmosphere device will be more in depth investigated in a new research project starting in 2007

Chemfire : a zone model for predicting chemical effects of pool fire in a single forced ventilation enclosure

International audienceZone models have been developed since the early 60s for the prediction of fire parameters such as smoke temperature, smoke filling and movement in multi-compartment buildings. Unfortunately, one major difficulty in current zone models is that heat and chemical species release rates in relation with a given fire source term are usually to be provided as input data. A new zone model for prediction of thermal and chemical effects of pool fire in a forced ventilated enclosure has been developed. The novelty of the approach relies in particular on the provision of three sub-models that are used for reducing the number of input data needed for a given simulation. The burning rate history of liquid pool fire is calculated from a vaporisation sub-model. A solid flame sub-model is used for predicting radiative properties of flame. Yields of chemical species are estimated from a dedicated sub-model of combustion. This zone model has received some validation for use in forced ventilated enclosures only. Promising results have been obtained

Use of ASTM E 2058 fire propagation apparatus for the evaluation of underventilated fires

International audienceThe apparatus originally called the 50 kW lab-scale flammability apparatus in the USA and Tewarson apparatus in Europe is a polyvalent fire calorimeter that was recently described in its updated version in ASTM E 2058, under the name of Fire Propagation Apparatus (FPA). This paper deals with the use of such a fire calorimeter implemented by INERIS in year 1997, and which has now been used for both research and services to private customers, in a routine manner since 1998. The paper focuses on the experience achieved so far by the Institute with this apparatus for the detailed characterization of ventilation controlled fires of industrial products that are likely to govern the accidental fire scenarios in fire resistant enclosures. Such hazardous confined spaces can be frequently encountered in industry and transportation infrastructures. In particular, relevant testing procedures and potential technical problems are discussed based on inlet air flow restriction or use of oxidizing flows diluted by nitrogen or carbon dioxide. Results regarding under-ventilated fires of a variety of products not belonging to polymers are presented to illustrate the capability of the apparatus to qualify such types of fires. Eventually, the ability of the equipment to provide detailed characterization of the fire chemistry of the combustion gases and related influence of ventilation rate, using specific additional sampling and chemical analysis is pointed out through examples

Biofuels for transport in the 21th century : why fire safety is a real issue

International audienceYears after pioneering development of sugar cane ethanol in Brazil (started in the mid 70's), with the new century venue we are assisting of a booming industry regarding biofuels for transportation in general, at international level. However, fire safety has not appeared so far as a potential bottleneck for future sustainable development, nor has it been anticipated that fire safety misleading judgements or lack of safety management might act as a non technical barrier for sustainable development. This paper is a first contribution to discuss these issues within the fire safety community aiming at identifying research needs and bring a first overview based on life cycle and whole value chain perspectives of biofuels for transport. This contribution is a first output from a National research program named BIOSAFUEL piloted by INERIS, comprising a first analysis of fire risk typology presented by socalled in Europe 1st generation technologies of biofuels. When the first statement is to consider that fire safety aspects are not likely to be that much critical on a technical point of view, the analysis is showing that safety related issues -and more especially fire safety related issues- with biofuels are not correctly summarized by simply saying that fuel ethanol is a flammable product whereas biodiesel is not, from a regulatory point of view. A more in-depth analysis is needed, that will, in addition, have to consider significant changes in biofuel technologies in the future

The effect of oxygen concentration on CO yields in fires

International audienceIn addition to global ventilation effects on fires, vitiation of air is a ventilation related phenomenon that can also affect the generation of chemical species in a built environment. The paper is a contribution to the study on the subject. Experiments were performed at lab-scale with the Fire Propagation Apparatus in order to study the effect of air vitiation on the CO yield. Results are also presented for the fuel burning rate. Both carbon dioxide and nitrogen were used as diluents in the inlet air flows. The oxygen concentration was decreased stepwise until the extinction point was reached. A first set of experiments was performed in well-ventilated fire conditions (equivalence ration between 0.1 and 0.25). A second set of experiments was carried out in under-ventilated fire conditions (equivalence ratio equal to 1.1). The results revealed useful for improving the combustion sub-model predictions in a zone model under development

A two-thermocouple probe for radiation corrections of measured temperatures in compartment fires

International audienceBare-bead thermocouples are widely used for measuring temperature fields in compartment fires. It is well-known that temperature readings using such a device call be significantly affected by radiation errors, the apparent thermocouple junction temperature being thus different from the true gas temperature. However, a probe consisting of two thermocouples of unequal diameters, but made of the same material can be used for estimating the gas temperature in a fire environment. Using a steady-state heat transfer model applicable to a bare-bead thermocouple, a very simple rule is proposed for the estimation of radiation errors when temperatures are measured by use of two thermocouples of different diameters. Radiation errors obtained from this simple rule are compared and discussed with experimental results involving a compartment fire with pyridine as the fuel