Oxygen Consumption Cone Calorimetry

One of the most important parameters that can be nsed to characterise a fire is the rate of heat release. It provides an indication of the size of the fire, the rate of fire growth and consequently the release of smoke and toxic gases, the time available for escape or suppression, the type of snppressive action that are likely to be effective and other attributes that define the fire hazard. Methods based on the oxygen consumption principle are now available to measnre the rate of heat release reliably and accurately. The principle depends upon the fact that the heats of combustion of organic materials per unit of oxygen consumed are approximately the same. This is because the processes in the combustion of all these prodncts involve the breaking of C-C and C-H bonds (which release approximately the same amonnt of energy) with the formation of CO2 and water. 

The cone calorimeter is the most generally accepted and powerful instrument in this field. Originally developed by Vytenis Babrauskas of the Centre for Fire Research at NIST, it is now available as a complete instrument embodying specific safety and 

This instrument has been used for the evaluation of buildings, furniture, transport, aerospace, wood and electrical materials and composites. Polymers to which this technique has been applied include PP and PP-composites [42], ethylene-vinyl acetate copolymers [43], polyamide-6,6 [27], silicate-siloxane composites [44], glass-phenolic composites [45], polyolefins [46], conveyor belt materials [47] and roofing materials [48]. 

The US Naval Surface Warfare Centre, Carderock Division [49] used cone calorimetry to evaluate several alternative glass reinforced brominated vinyl ester resins containing various FR including aluminium trihydrate (ATH). Cone calorimetry was carried out at three different fluxes, 25, 50 and 75 kW/m. Smoke production and carbon 

Bromination of vinyl-ester resin imparts fire retardancy as manifested by flame spread and lower RHR [50]. However, this fire-retardant system functions primarily in the gas phase causing incomplete combustion. As such, brominated resins produce dense smoke, and an increase in the yield of CO and HBr. Recent interest in the use of non-halogenated organic-matrix composite materials in US Navy submarines and ships has generated the requirement for significant improvement in the flammability performance of these materials including reduction in the amount of smoke, CO and corrosive combustion products. 

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As a consequence of a very serious fire under the steel roofs in a large car plant in USA the Underwriters Laboratories Inc., developed a new UL test method, which uses oxygen consumption cone calorimetry to quantify roof covering materials. This test was used to quantify the contribution of roof covering materials to the fire under the roof by capturing effluent from beneath the roof assembly and recording the rate of heat production in kW/min. 

During the cone calorimeter experiment, the main result of heat release, especially HRR8187 and THR, is determined by oxygen consumption calorimetry.88 89 In due course, different types of typical burning behavior give rise to characteristic curves of HRR. Some are illustrated schematically in Figure 15.6 81... 

Simplified cone calorimeters have been suggested for quality assurance testing in which mass.doss and/or temperature measurements replace the more complex oxygen consumption calorimetry. Published specifications for the cone calorimeter include... 

Instrumentation for the measurement of the flammability characteristics of polymers intended for use in mining, electrical, transport, furniture, construction materials is discussed in Chapter 17, including methods of identifying combustion products and the measurement of oxygen consumption by oxygen cone calorimetry. New methods based on pyrolysis - gas chromatography - mass spectrometry and laser pyrolysis time of flight mass spectrometry are also discussed. 

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