Esko Mikkola

Burning characteristics of selected substances: production of heat, smoke and chemical species

The cone calorimeter technique was employed to investigate the burning characteristics and composition of fire effluents of selected chemicals, including pesticides, compounds used in the chemical industry, liquid solvents and polymers. A controlled-atmosphere apparatus was utilized, allowing variation of the ventilation conditions in the test chamber. The quantities measured to determine the burning properties were time to ignition, rate of heat release, mass and mass loss rate of the sample and smoke production. The composition of the fire effluents was determined by Fourier-transform infrared spectroscopy and gas chromatography/mass spectroscopy analysis. The dependence on the availability of oxygen on a range of parameters has been examined. Both the degree of ventilation, expressed in terms of the global equivalence ratio of the system, as well as the local oxygen environment, reflected by the combustion efficiency, have been addressed.

Smoke gas analysis by Fourier transform infrared spectroscopy – summary of the SAFIR project results

The determination of toxic components from fire gases is difficult because the environment is hot, reactions are often temperature dependent, and a lot of soot may be produced. Due to the different properties of the gas components, a different timeconsuming procedure for each species has traditionally been used. The use of FTIR (Fourier Transform InfraRed) spectrometers as a continuous monitoring technique overcomes many of the problems in smoke gas analyses. FTIR offers an opportunity to set up a calibration and prediction method for each gas showing a characteristic spectral band in the infra-red region of the spectrum. The objective of this project was to further develop the FTIR gas analysis of smoke gases to be an applicable and reliable method for the determination of toxic components in combustion gases related to fire test conditions. The project included the following tasks: small scale and large scale sampling; analysis, calibration and software techniques; the verification of the method; and an interlaboratory trial. The optimum probe design, filter parameters and the most suitable sampling lines in terms of flow rate, diameter, construction material and operating temperature have been specified. The gas adsorption onto the filter and the soot have been measured. In the large scale, special concern was given to the probe design and the effects of the probe location in relation to the fire source as well as practical considerations of the sampling line length. Quantitative calibration and prediction methods have been constructed for different components present in smoke gases. Recommendations on how to deal with interferents, non-linearities and outliers have been provided and a verification method for the spectrometer for unexpected variations and for the different models have been described. FTIR measurement procedures in different fire test scenarios have been studied using the recommendations of this project for measurement techniques and analysis, and real precision values for specific test scenarios have been estimated. Also a proposal for draft standard of the FTIR method for smoke gas analysis has been prepared. An interlaboratory trial of the FTIR technique in smoke gas analysis was carried out to define the repeatability and reproducibility of the method in connection with a small scale fire test method, the cone calorimeter.

Toxic combustion products of three pesticides

Abstract In many countries, there are a large number of chemical plants and warehouses that handle and store substantial amounts of hazardous substances, such as pesticides. Chemical fires seem to be one of the most important hazards of these activities. However, very little information exists on combustion products in general, except for some information on combustion products from plastics, furnitures and fabrics. In this study, the aim was to gather, investigate and compare results obtained using different kinds of small-scale experiments. The test methods used were the DIN 53 436 furnace and the cone calorimeter. It is very important to obtain more information on combustion products which could be used in risk assessment of chemical storage facilities and for development of new environmentally safer chemical products. In this study, determination of the combustion products of only three pesticides has been carried out. However, hundreds of pesticides are in use worldwide. Therefore, it is necessary to continue this type of study with other pesticides in order to establish general rules for prediction of combustion products. Investigations of the environmental impact of combustion products and suitable methods of fire-fighting in different situations are important.

European classes for the reaction to fire performance of wood products

The new classification system for the reaction to fire performance of building products in Europe has been applied to five different product families of wood: Wood-based panels, Structural timber, Glued laminated timber, Solid wood panelling and cladding and Wood flooring as being ‘products with known and stable fire performance’. The European classification system includes two sub-systems, one main system for all construction products except floorings and the other for flooring products. Wood properties such as density, thickness, joints and types of end use application including different substrates have been studied thoroughly and are included in the classification. Most wood products fall in classes D-s2, d0 or Dfl-s1 (for floorings). Testing has been performed according to EN 13823 (2002) SBI- Single Burning Item test, EN ISO 9239-1 (2002) Radiant panel test, and EN ISO 11925-2 (2002) Small flame test. In all, more than one hundred wood products in different end use applications have been studied. Clear relationships between the main Euroclass fire performance parameters and product parameters (such as density and thickness) have been demonstrated. Tables with reaction to fire classification of different wood products and end use applications have been developed, approved by the European Commission and published in their Official Journal. This procedure is ongoing with further official decisions to be published. ZusammenfassungDas neue europäische Klassifizierungssystem zum Brandverhalten von Bauprodukten gilt für die fünf Produktgruppen Holzwerkstoffe, Bauholz, Brettschichtholz, Wand- und Deckenbekleidungen aus Massivholz sowie Holzfußböden, die als “Produkte mit bekanntem und abschätzbarem Brandverhalten” gelten. Das europäische Klassifizierungssystem wird in zwei Kategorien unterteilt: eine Hauptkategorie für alle Bauprodukte mit Ausnahme von Bodenbelägen und eine Kategorie für Bodenbeläge. Holzeigenschaften, wie zum Beispiel Rohdichte, Dicke, Verbindungen und Anwendungsarten einschließlich verschiedener Trägerplatten wurden eingehend untersucht und in die Klassifizierung einbezogen. Die meisten Holzprodukte werden den Klassen D-s2, d0 oder Dfl-s1 (Fußböden) zugeordnet. Prüfungen erfolgten nach den Normen EN 13823 (2002) thermische Beanspruchung durch einen einzelnen brennenden Gegenstand, EN ISO 9239-1 (2002) Brandverhalten bei Beanspruchung mit einem Wärmestrahler und EN ISO 11925-2 (2002) Entzündbarkeit von Bauprodukten bei direkter Flammeneinwirkung. Insgesamt wurden über einhundert Holzprodukte in unterschiedlichen praktischen Anwendungsarten untersucht. Eindeutige Zusammenhänge zwischen den Hauptparametern zum Brandverhalten nach der Euroklasse und den Produktparametern (wie zum Beispiel Rohdichte und Dicke) wurden dargestellt. Tabellen mit der Klassifizierung des Brandverhaltens verschiedener Holzprodukte und Endanwendungen wurden erstellt, von der Europäischen Kommission genehmigt und in deren Amtsblatt veröffentlicht. Dieses Verfahren dauert noch an. Die Veröffentlichung weiterer amtlicher Entscheidungen steht noch aus.

Burning characteristics of selected substances: influence of suppression with water

The influence of suppression with water spray on the burning characteristics and composition of fire effluents of nylon, polypropylene and two industrial chemicals was investigated The experiments were performed using a controlled-atmosphere cone calorimeter in which the ventilation conditions could be altered. The water spray was applied with a single horizontally positioned nozzle. In the experiments time to ignition, rate of heat release, sample weight and smoke production as well: as the composition of the fire effluents were measured; the chemical analysis techniques employed were Fourier-transform infrared spectroscopy and gas chromatography/mass spectroscopy. The results give quantified information on the effects that water application may have on the burning and the properties of the exhaust gases. A comparison with results of similar experiments with no water application reveal notable changes, e.g. in the production of the toxic fire effluents.

Ignitability Comparisons between the ISO Ignitability Test and the Cone Calorimeter

Ignitability tests were completed on three materials using the ISO ignitability apparatus and the Cone Calorimeter. A large number of repli cate tests were made at each heat flux level to obtain reliable standard devia tion values for the results. The possible errors in results were minimized using the very same external conditions. Both methods can be used to measure ignit ability, although there is some systematic difference in the measured ignition times. The ISO ignitability tests give slightly shorter ignition times caused by difference in convective heat flow. These results show, however, that it is possi ble to find a simple relation between the results of the two test methods.

Fire retardants and product behaviour in fire tests

Fire safety aspects of polymeric materials in various types of use have led to finding effective ways to reduce the ease of ignition, flame spread and heat evolved as well as the amount of smoke, toxic and corrosive gases produced. Depending on the polymer and the end-use application of the product, different fire-retardant methods are used with the aim of passing criteria in fire tests related to the end-use application. In most cases the classification criteria for reaction to fire behaviour are based on the assumption that early phase fire development is the main hazard. This means that the key elements for effective fire retardants are to delay ignition and to reduce heat release and smoke production, at least during the early part of exposure. This short review intends to summarize the different aspects of product performance in fire testing relevant for product development and classification purposes.