Cone Calorimeter
The cone calorimeter is a device used to burn small samples of various materials and gather data on heat release, combustion products, and other parameters associated with combustion.
How does it work?
The cone calorimeter is a fire test intrument based on the principle of oxygen consumption calorimetry. This empirical principle is based on the observation that, generally, the net heat of combustion of any organic material is directly related to the amount of oxygen required for combustion. Approximately 13.1 MJ of heat are released per kilogram of oxygen consumed.
At the core of the instrument is a radiant electrical heater in the shape of a truncated cone (hence the name). This heating element irradiates a flat horizontal sample, 100 mm x 100 mm and up to 50 mm thick, placed beneath it, at a preset heating flux of up to 100 kW/m2. The sample is placed on a load cell for continuous monitoring of its mass as it burns. Ignition is provided by an intermittent spark igniter located 13 mm above the sample.
The gas stream containing the combined combustion products is captured through an exhaust duct system, consisting of a high-temperature centrifugal fan, a hood, and an orifice-plate flowmeter. The typical air flow rate is 0.024 m3/sec. Oxygen concentration in the exhaust stream is measured with an oxygen analyzer capable of an accuracy of 50 ppm., and the heat release rate is determined by comparing the oxygen concentration with the value obtained when no sample is burning.
Smoke obscuration measurements are made in the exhaust duct by a helium-neon laser, with silicon photodiodes as main beam and reference detectors, and appropriate electronics to derive the extinction coefficient and set the zero reading. Locations are also provided in the exhaust duct for additional sampling probes, to determine concentrations of other combustion products, such as the carbon oxides.
All data are collected with a PC, which records data continuously at fixed intervals of a few seconds while a test is being conducted.
The cone calorimeter is used to determine the following principal fire properties: rate of heat release per unit area, cumulative heat released, effective heat of combustion, time to ignition, mass loss rate, and total mass loss, as well as smoke obscuration.
The test method for using the cone calorimeter is ASTM E 1354, "Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter." This test method is available from ASTM or in most libraries, including WPI's Gordon Library.
Maintained by webmaster@wpi.eduLast modified: August 08, 2006 09:12:55