A study on the flame spread over partition materials

Pao Yue-kong Library Electronic Theses Database

A study on the flame spread over partition materials

 

Author: Leung, Cheuk-wai
Title: A study on the flame spread over partition materials
Degree: Ph.D.
Year: 2007
Subject: Hong Kong Polytechnic University -- Dissertations.
Flame spread.
Building materials -- Fire testing.
Department: Dept. of Building Services Engineering
Pages: xxix, 148, [261] leaves : ill. ; 31 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2094037
URI: http://theses.lib.polyu.edu.hk/handle/200/890
Abstract: Flame spread over partition materials is one of the key driving forces in the fire growth in a compartment. An appropriate test method should be selected which is the key subject of this thesis. The study includes three major areas. The first area includes review of flame spread mechanisms, local legislative requirements on flame spread and use of construction materials. Partition materials with high flame spread hazard were identified. The likelihood of flashover in a typical small room covered by those materials was predicted using an empirical equation based on ventilation factor. Standard flame spread tests were reviewed and compared. Possible correlations of the tests were made. The second area is a series of full-scale burning tests on common partition and lining materials carried out in collaboration with the Harbin Engineering University in Northeast China. Wood partitions, fire retardants and plastics were tested in three groups of tests in a room calorimeter similar to ISO 9705. Heat release rate, time to flashover and flame spread rates were measured. Tests included a fully-lined room under a 45 kW small fire located at the room corner, products covered on one side of the room under a 100 kW growing fire and tests of the products under a 2.3 MW flashover fire. Results showed that products with limited flame spread and heat release rate under the small growing fire tests would give out much more heat and even fully consumed in the flashover fires. Taking plywood partitions treated with fire retardant as an example, testing under a 45 kW fire would reduce the peak heat release rate by 90 %. Onsetting flashover might be prevented. The same fire retarded partitions gave faster flame spread rate by 26 % than untreated plywood under the 100 kW growing fire. Under the flashover fire, the partition was burnt and reached over 500 kW within 200 s and released over 49 MJ within 400 s. Testing under flashover is proposed to evaluate the actual contributions of the materials in a fire. Such approach is recommended to the local Authority on assessing flame spread over partition materials. In the third area, mathematical flame spread models were reviewed as alternatives to assess flame spread over materials. A new model was developed in which the radiation from the flame, treated as a two-dimensional homogeneous gas/particulates medium, is described using a gray soot model with an absorption coefficient. The model is used to predict the radiative heat transfer, flame front and burnout front of an opposed flame spread problem in the Lateral Ignition and Flame spread Test (LIFT) setup using data from the Cone Calorimeter. Limitations of the models were identified and further improvements were suggested.

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