Oxygen Consumption Calorimetry Research Articles

The Measurement of Heat Release from Oxygen Consumption in Sooty Fires

This paper is a further contribution to the development of practi cal relationships based on oxygen consumption calorimetry to calculate the rate of heat release (RHR) in fires. The measurement of the RHR based on oxygen consumption was promoted in the 1980s. Previous workers introduced and as sessed the significance of adequate correction factors to take into account in completeness of combustion as reflected by carbon monoxide release. This paper focuses on materials releasing large amounts of soot in combustion. Classical oxygen consumption relationships are reviewed to derive adequate calculation procedures integrating the soot contribution. An analysis 1Author to whom correspondence should be addressed. E-mail: sylvain.brohez@fpms. ac.be of the significance of the suggested soot correction factor is discussed through theoretical considerations as well as from results of lab-scale experiments.

Soot Generation In Fires: An Important Parameter For Accurate Calculation Of Heat Release

Oxygen consumption (OC) calorimetry and carbon dioxide generation (CDG) calorimetry are usual methods to determine the heat release rate (HRR) in bench-scale and large-scale fire tests. The paper emphasises on measuring problems associated with fires releasing large amounts of soot. Until now, the soot-related energy transfer was hardly ever taken into consideration in practical applications of HRR calculations. From standard CDG calorimetry, a generalised relationship is introduced in order to take into account the soot generation in the accurate determination of the heat release produced in sooty fires. The analysis of the significance of this correction factor is discussed by theoretical consideration as well as from results of lab-scale experiments recently carried out on chemicals by means of the INERIS fire calorimeter.

Investigations of conveyor belts flammability. Comparison of flammability assessment using the large-scale gallery test and cone calorimeter

The paper describes results of investigations of conveyor belt flammability in full scale, using the large-scale gallery method and using cone calorimeter. On the basis of oxygen consumption calorimetry, the amounts of heat release during burning of conveyor belts were calculated. A correlation was found between results of conveyor belt flammability obtained using both methods. Criteria for conveyor belt flammability assessment were established for the cone calorimeter method, which define a level that would be equivalent to that for the large-scale gallery test.

Combustion behaviour of ethylene vinyl acetate copolymer‐based intumescent formulations using oxygen consumption calorimetry

This work compares the fire degradation of ethylene-vinyl acetate 8% copolymer (EVA8) with two flame-retarded formulations, using the cone calorimeter. The first one, EVA8/ammonium polyphosphate (APP) leads to the protection of the material, in the conditions of a fire, by means of blowing up and weak carbonization. The addition of polyamide-6 (PA-6) in EVA8/APP improves the protection by forming an intumescent carbonaceous shield. The fire hazard of the virgin polymer and of the FR systems are quantified, in terms of rate of heat release, weight loss, effective heat of combustion, volume of smoke production and CO and CO2 production. It assesses the effectiveness of the fire retardant additives APP and APP/PA-6 in EVA8-based materials under simulated real fire test conditions. The respective temperatures of the degradation front are deduced from the weight loss data recorded in the course of the cone calorimeter experiments and the results of the invariant kinetic parameters method applied to the different specimens. The addition of APP/PA-6 in EVA8 leads to a superficial phenomenon; the degradation zone is thus located on the upper volume of the specimen during all the exposure to the heat flux. © 1998 John Wiley & Sons, Ltd.

Combustion behaviour of ethylene vinyl acetate copolymer-based intumescent formulations using oxygen consumption calorimetry

This work compares the fire degradation of ethylene-vinyl acetate 8% copolymer (EVA8) with two flame-retarded formulations, using the cone calorimeter. The first one, EVA8/ammonium polyphosphate (APP) leads to the protection of the material, in the conditions of a fire, by means of blowing up and weak carbonization. The addition of polyamide-6 (PA-6) in EVA8/APP improves the protection by forming an intumescent carbonaceous shield. The fire hazard of the virgin polymer and of the FR systems are quantified, in terms of rate of heat release, weight loss, effective heat of combustion, volume of smoke production and CO and CO2 production. It assesses the effectiveness of the fire retardant additives APP and APP/PA-6 in EVA8-based materials under simulated real fire test conditions. The respective temperatures of the degradation front are deduced from the weight loss data recorded in the course of the cone calorimeter experiments and the results of the invariant kinetic parameters method applied to the different specimens. The addition of APP/PA-6 in EVA8 leads to a superficial phenomenon; the degradation zone is thus located on the upper volume of the specimen during all the exposure to the heat flux. © 1998 John Wiley & Sons, Ltd.

Heat release rate in evaluation of conveyor belts in full-scale fire tests

The theoretical bases for calculation of heat release rate during burning of conveyor belts in the fire-testing gallery has been presented. Taking as an example the results of measurements of oxygen, carbon dioxide and monoxide content in the products of combustion of conveyor belts during the testing of their flammability in the full-scale fire gallery, the possibility has been demonstrated for using the calculations of heat release rate in an assessment of conveyor belt flammability. The total quantity of heat released during the belt fire in the experimental gallery can provide the basis to develop a new method of testing as well as the criteria for assessment of fire resistance of the conveyor belts using oxygen consumption calorimetry. © 1997 John Wiley & Sons, Ltd.

The Measurement Of Heat Release Rates By Oxygen Consumption Calorimetry In Fires Under Suppression

A series of open-space fire experiments was conducted at the National Fire Laboratory (NFL) to validate the capabilities of the NFL room-size oxygen-consumption calorimeter, and to assess the importance of accounting for actual water vapour content in the exhaust gases in calculating heat release rates (HRR). Water spray was used to partially suppress some of the fires, and to add significantly to the humidity of the exhaust gases. The equations normally used in the fire research community for oxygen calorimeter assume unsuppressed fires, and that water vapour in the exhaust gases is due solely to the humidity of the incoming air and to combustion reactions. This paper derives the basic equations for computing heat release rates based on the principle of nitrogen balance. The general equations take into account all sources of water vapour, including incoming air, combustion reactions, and evaporation due to suppression. The equations are then simplified to i) neglect all humidity, and, ii) consider only the humidity of the incoming air. The predictions of the HRR from the three sets of equations are compared with the HRR calculated for unsuppressed fires and with the HRR obtained by measuring fuel consumption rates. As long as the water vapour content in the exhaust gases is less than 7 %, both simplified equations can be used to measure the HRR of partially suppressed fires, without significant error. For larger concentrations of water vapour, water vapour should be measured and the full equations used.

Characterization of the fire behaviour of a burning passenger car. Part I: Car fire experiments

Three full-scale fire experiments on passenger cars are described. The cars, manufactured in the late 1970s, were equipped as in practice with oil, petrol and ordinary passenger cabin materials. The experiments were performed indoors under a hood which collected the combustion products. The cars were ignited either from the passenger cabin or beneath the engine with a heptane tray. Rate of heat release by means of oxygen consumption calorimetry, mass change and rate of mass change, heat flux, CO and CO 2 production rate, smoke production rate, gas temperatures above the car and temperatures inside the car were determined as a function of time.

An Intermediate‐Scale Calorimeter for building materials and assemblies

AbstractA new Intermediate Scale Heat Release Rate Test Method is being developed primarily for testing assemblies in the vertical mode. Using the oxygen consumption calorimetry methodology and exhaust collection systems that already exist in many laboratories in the US and around the world, the apparatus is very economical to install. The sample size lends itself to reptitive testing in a short period of time. Sample preparation is generally quick and easy. Further development of the method should progress now that the method has been introduced at ASTM and will be introduced formally into ISO in the near future. There has been a favorable response by several laboratories who are considering construction of the apparatus. Additional assemblies tests are already underway and additional data will be presented in the near future.

The OSU Heat Release Unit as a Screening Tool for California TB 133

The California TB 133 (TB 133) full-scale burn test was adopted by Illinois and Minnesota in 1990 as a performance standard for furniture to be used in places of public occupancy. TB 133 will become effective in California on January 1,1992 and is under consideration in Ohio and several other states. Since full-scale burn tests are expensive, we embarked on a program to deter mine if the OSU Heat Release Unit could be used as a screening test for TB 133. The percentage weight loss of foam/fabric composites after ten minutes in the OSU Unit at a radiant heat flux of 1.0 Watt/cm2 appears to be a good predictor of TB 133 performance. A series of 39 upholstery fabric/melamine-modified polyurethane foam composites were tested in BASF Corporation's Wyandotte, Michigan TB 133 burn facility and in our OSU Heat Release Unit. We found: · 11 of 12 samples which clearly failed the Cal TB 133 test lost over 40% of their weight at a heat flux of 1.0 Watt/cm2 in the OSU test. · 22 of 23 samples which clearly passed the Cal TB 133 test lost less than 40% of their weight at 1.0 Watt/cm2. · Four samples marginally passed the Cal TB 133 test and their weight loss values could not be correlated. The TB 133 criteria adopted in mid 1990 was used for this series of tests rather than the newer criteria using oxygen consumption calorimetry. All of the TB 133 failures in this study were due to weight loss using fabric-covered foam cushions on a metal test frame. No side arms were used. Work is continu ing to determine whether this correlation can be extended to other foam/fabric combinations.

Heat production in isolated heart myocytes: differences among species

A new calorimetry method has been developed to measure heat production from heart cell suspensions under continuous perfusion. The method is technically independent of the temperature at which the measurements are made, allows full control of the perfusion media, and is suitable for various biological preparations such as cells from diverse tissues, membrane vesicles, or skinned cells. The resting heat rate (Hr) measured at 18.5 degrees C in three different species (19.2 +/- 0.43, 12.8 +/- 0.56, and 9.4 +/- 0.52 mW/g dry wt for rat, guinea pig, and rabbit ventricular myocytes, respectively) agrees with that obtained with other methodologies such as oxygen consumption, thermopiles, and whole heart calorimetry. The Hr measurements showed an excellent correlation with the percentage of rod-shaped cells, indicating that rounded cells are metabolically inactive. Although the time course of the effect of increasing extracellular [K] was dependent on the species, the new steady level of Hr observed under higher extracellular [K] was significantly higher in all three species (+8.3 +/- 1.2, +9.5 +/- 4.0, and +9.3 +/- 2.7 mW/g dry wt for rat, guinea pig, and rabbit ventricular cells, respectively). This indicates that the commonly used "arrested-heart" preparation (with high extracellular [K]) for evaluation of basal metabolism most probably overestimates the real resting values. The present results also show that the wide range of resting metabolism reported in whole tissue is not due to cellular heterogeneity nor to myocyte interaction and supports the idea of an inverse relationship between resting metabolism and body weight or animal size across species.