ISO 19703:2010 pdf free download – Generation and analysis of toxic gases in fire一Calculation of species yields, equivalence ratios and combustion efficiency in experimental fires.
5.4 Data collection
5.4.1 Data acquisition
Time-resolved data or time-integrated data may be acquired. The method of data acquisition should be
specified in the test protocol.
5.4.2 Measured data and observations
Most of the following data parameters should be used to calculate yields, equivalence ratios and combustion efficiencies in experimental fires. Usually, the units applied to data should be dictated by the operational procedure associated with a particular piece of apparatus. The following are a number of suggested typical units:
a) mass loss of the test specimen, derived by measuring the test specimen mass before and after test to give overall mass loss (expressed in milligrams, grams or kilograms) or mass loss fraction (expressed in mass percent, grams per gram or kilograms per kilogram), or by measuring the specimen mass throughout a test to give mass loss rate (expressed in milligrams per second, grams per minute or kilograms per minute);
b) gas and vapour concentrations and oxygen depletion (expressed in volume percent, volume fraction, microlitres per litre, milligrams per litre or milligrams per cubic metre);
c) smoke particulate concentration (expressed in milligrams per litre or milligrams per cubic metre) and smoke obscuration (expressed in optical density per metre or square metres per kilogram);
d) heat release (expressed in kilojoules per gram), used to calculate combustion efficiency, forms part of the protocol for some apparatuses;
e) combustion mode, time to ignition (expressed in minutes or seconds) and whether the specimen flames or not throughout the test.
6 Calculation of yields of fire gases and smoke, stoichiometric oxygen demand and recovery of key elements
6.1 Calculation of measured yields from fire gas concentration data
In experimental fires, the mass yield, gas’ of a gas can be calculated from the measured mass concentration of the gas of interest and the mass loss concentration of the material or from the total mass of gas generated and the total mass loss of material in accordance with Equation (2) (see Notes 1, 2 and 3):
Various other derivations are used in the literature. They are given in more detail in References [7], [8] and [9].
6.5.4 Relationship between mass measurement and light obscuration
Both large- and bench-scale test procedures tend to monitor the optical/obscurational properties of smoke. However, the mass concentration of smoke is sometimes useful (e.g. for input to field and zone computational models). A relationship between optical properties and mass concentration has been developed for post-flame generated smoke for a wide range of fuels under well-ventilated conditions[8]. Again, Bouguer’s law is the basis, relating the ratio of the transmitted and incident intensities to the mass concentration,n, of the smoke, the path length, L, through the smoke and the specific mass extinction coefficient,using Equation (40).