ISO 5660 Reaction to Fire Tests - Heat Release, Smoke Production and Mass Loss Rate

The "ISO 5660 Reaction to fire tests - Heat release, smoke production and mass loss rate" standard published by the International Organization for Standardization (ISO) consists of a number of subsections published under the same title. Namely,

• The standard "ISO 5660-1 Part 1: Heat release rate (cone calorimeter method) and smoke production rate (dynamic measurement)" describes a method for evaluating the heat release rate and dynamic smoke production rate of samples exposed in a horizontal position to controlled irradiance levels with an external igniter. The heat release rate is determined by measuring the oxygen consumption derived from the oxygen concentration and the flow rate in the combustion product stream. The ignition time (continuous flame) is also measured in this test. The dynamic smoke production rate is calculated from measuring the attenuation of a laser light beam by the combustion product stream. Smoke blackout is recorded throughout the test, regardless of whether the sample is ignited.

The test method is generally based on the observation that the net heat of combustion is proportional to the amount of oxygen required for combustion. The relationship is that approximately 13,1 x 10³ ^kJ of heat is released for every kilogram of oxygen consumed. Samples in the test are burned under ambient air conditions while exposed to a predetermined external irradiation range of 0 kW m⁻² ^to 75 kW ^m⁻² , and oxygen concentrations and exhaust gas flow rates are measured. This test method is used to evaluate the contribution that the tested product can make to the heat release rate during its exposure to fire. These properties are determined on small, representative samples.

The principle of smoke measurement is generally based on the observation that the light intensity transmitted through the volume of combustion products is an exponentially decreasing function with distance. This is commonly referred to as Bouguer's law. Samples in the test are burned under ambient air conditions while being exposed to a predetermined external irradiation range of 0 kW m⁻² ^to 75 kW m⁻² ^, and measurements of smoke darkening, exhaust gas flow rate, and mass loss rate of the sample are taken. Smoke darkening is measured as a fraction of the laser light intensity transmitted through the smoke in the exhaust duct. This fraction is used to calculate the damping coefficient according to Bouguer's law.

Test results are reported in terms of smoke production and smoke production rate, both normalized to the exposed sample surface area. The smoke production rate is calculated as the product of the extinction coefficient and the volumetric flow rate of smoke in the exhaust duct. Smoke production is calculated by numerically integrating the smoke production rate over the considered time interval. Reported variables are area-normalized because smoke production is proportional to area. The test method is used to evaluate the contribution of the tested product to the smoke propagation rate and the amount of smoke produced during involvement of a well-ventilated fire. These properties are again determined on small, representative samples.

• The standard "ISO 5660-2 Part 2: Smoke production rate (dynamic measurement)" specifies a small-scale method for evaluating the dynamic smoke production rate of essentially flat samples subjected to controlled levels of radiant heating under well-ventilated conditions, with or without an external igniter. The smoke production rate is calculated from measuring the attenuation of a laser light beam by the combustion product stream. Smoke obscuration is recorded throughout the test, regardless of whether the sample is aflame or not. The measurement system prescribed by this standard is an extension of the instrument described in ISO 5660-1. Therefore, this standard is used in conjunction with ISO 5660-1.

This test method is based on the observation that the light intensity passing through a volume of combustion products is an exponentially decreasing function of distance. This is often referred to as Bouguer's law. Samples in the test are exposed to a predetermined external irradiation range while being burned under ambient air conditions, and smoke obscuration, exhaust gas flow rate, and the sample's mass loss rate are measured. Smoke obscuration is measured as the fraction of the laser light intensity passing through the smoke in the exhaust duct. This fraction is used to calculate the extinction coefficient according to Bouguer's law.

Test results are reported in terms of smoke production and smoke production rate, both normalized to the exposed sample surface area. The smoke production rate is calculated as the product of the extinction coefficient and the volume flow rate of smoke in the exhaust duct. Smoke production is calculated by numerical integration of the smoke production rate over the considered time interval. Reported variables are area-normalized because smoke production is proportional to area. The test method is used to evaluate the contribution of the tested product to the smoke propagation rate and the amount of smoke produced during participation in a well-ventilated fire. These properties are determined on small, representative samples.

• The standard "ISO 5660-3 Part 3: Guidance on Measurement" examines the limitations of the cone calorimeter currently used for building products and suggests ways to overcome some of these for other product types and other application areas. This standard compiles knowledge from extensive experience with the instrument into a set of guidelines that will help standardize the use of the cone calorimeter in this broader context.

This standard provides specific guidance on aspects of sample preparation and the behavior of samples exposed to radiant heat, such as melting, disintegration, and swelling. It discusses the importance of sample thickness and substrate use, and substrate fixation methods. It also provides advice on approaches to testing various non-standard products. It also provides recommendations on instrument calibration techniques, selection of appropriate heat flux levels, and firing protocols. In addition to guidance for operators, this standard also includes recommendations for presenting test results.

• ISO 5660-4 Part 4: Measurement of low heat release levels describes a method for evaluating materials and products that produce low levels of heat release when exposed to the high irradiance levels typical of fully developed fires. It differs from ISO 5660-1 by specifying elements such as the specific sample size, sample holder, sample orientation, volumetric flow rate, and the irradiance levels at which the test is performed. The test method described in this standard is intended for use on products and materials containing only small amounts of combustible elements, for example, test samples giving a total heat release of 0,75 MJ/m2 to 15 MJ/m2. A test method for samples giving a moderate to high total heat release is included in ISO 5660-1. The information obtained from this test method in this standard can also be used for fire safety engineering purposes. As in ISO 5660-1, heat release rates are not measured directly and in absolute terms, but are calculated theoretically using an experimentally derived constant of proportionality that relates the heat released to the measured oxygen consumption.

Measurement of heat release rate and total heat release is used to quantify the test sample's ability to ignite and contribute heat to a fire. It is generally based on the observation that a material's net heat of combustion is directly related to the amount of oxygen required to burn it. This relationship is approximately 13,1 x 103 kJ of heat released per 1,0 kg of oxygen consumed. Optionally, additional measurements of carbon dioxide and carbon monoxide can be made and used in the calculation of heat release.

• The standard "ISO 5660-5 Part 5: Heat release rate (cone calorimeter method) and smoke production rate (dynamic measurement) in reduced oxygen atmospheres" describes the apparatus and procedure used to measure fire response behavior under reduced oxygen atmospheres. Continuous measurements are made to calculate heat release rates, smoke and specific gas production rates, and mass loss rates. Ignition time measurements are also made to obtain ignition behavior. Pyrolysis parameters of samples exposed to controlled irradiance levels and controlled oxygen supply levels can also be determined.

Different reduced oxygen atmospheres within the test environment are achieved by controlling the oxygen volume concentration of the inlet gas fed to the chamber (vitiation) or the total atmospheric volume fed to the chamber (ventilation). Oxygen volume concentration ranges below 20,95 percent oxygen can be examined. The instrument is not designed to control enriched oxygen conditions above 20,95 percent atmospheric oxygen concentration. The measurement system prescribed in this standard is based on the cone calorimeter apparatus described in ISO 5660-1. Therefore, this document is intended for use in conjunction with ISO 5660-1.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, boasts a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the ISO 5660 "Reaction to fire tests - Heat release, smoke production, and mass loss rate" standard.