MATERIAL TYPE Δ Acoustic Tile Lauan Plywood Fir Plywood Particle Board Melamine/Hardboard 100 50% Figure 8. Flame spread data obtained by ASTM E-84 Tunnel, E-162 Radiant Panel and Corner Fire Tests. 650 and vertical photometric smoke measurements during the full-scale corner fire tests. It should be noted that the chamber method measures the maximum accumulated smoke level under a closed system condition whereas the full-scale test is a measure of the smoke accumulation in a room with an open doorway through which a significant portion of the smoke leaves. The latter measurement obviously depends upon the degree of ventilation and the intensity of the room fire, and should not be considered unique. Despite this, correlation is fair as indicated in the figure. A reproducible fire with a standardized wood crib was found to be capable of duplicating the essential features such as: temperature, heat flux and heat output levels, and the size and shape of the flame of typical well ventilated incidental fires. The presence of combustible interior finish materials has a significant influence on fire growth in buildings by shortening the time to reach full involvement of combustible contents, enhancement of rapid spread of fire, and increased generation of heat and smoke. The potential fire hazard of interior finish materials can be measured by use of a corner fire test in which the materials to be evaluated are installed as the walls and ceiling in a typical full-size room. This arrangement permits separate measurement of ease of ignition, flame spread rate, flame penetration, and smoke producing properties during a single test. The authors wish to thank Mr. C. F. Veirtz, Mr. T. F. Maher and Mr. B. E. Ramey for their assistance in the experimental work and Mr. J. W. Raines for his help in modifying the computer program to process the outputs of the data acquisition system. This work was supported in part by the United States Department of Housing and Urban Development. [1] Surface Flammability as Determined by the FPL 8-Foot Tunnel Method, U.S.D.A. Williamson, R. B. and Baron, F. M. A Corner Fire Test to Simulate Fang, J. B., Measurement of the Behavior of Incidental Fires in a Compartment (to be published). [2] [3] [4] Parker, W. J., The Development of a Test for Ease of Ignition by Flame [5] [6] [7] [8] Standard Method of Test for Surface Burning Characteristics of Building Surface Flammability of Materials Using a Radiant Heat Source, ASTM E162-67, Parker, W. J. and Long, M. E., Development of a Heat Release Rate Calori- Lee, T. G., Interlaboratory Evaluation of the Smoke Density Chamber Test NATIONAL BUREAU OF STANDARDS SPECIAL PUBLICATION 411, Fire Safety Research, Proceedings of a Symposium Held at NBS, Gaithersburg, Md., August 22, 1973, (Issued November 1974) FIRE BUILD-UP IN REDUCED SIZE ENCLOSURES1 W. J. Parker and B. T. Lee National Bureau of Standards, Washington, D.C. A 30 x 30 x 32 inch enclosure was constructed to study the Key words: Fire tests; flashover; heat release rate; scale models; thermal radiation. Proper selection of wall, ceiling, and room furnishing materials can prevent the build-up of a serious fire in a room. Unfortunately, the fire performance of any material is difficult to assess on the basis of a single test or even from a series of laboratory tests. The fire behavior of a material must be evaluated along with the room and its furnishings so that the combination will have a low probability of full involvement in the event of an accidental ignition. Prerequisite to this approach, it is necessary to develop an understanding of the growth and spread of fire in the room. Instrumented compartment fires on both full and reduced scales can provide such information. However, smaller fires are more economical and manageable, and can be used to explore variables in a more expeditious and systematic manner. Reduced scale modeling methods for simulating the fire build-up in compartments have been developed at the Illinois Institute of Technology Research Institute (IITRI) [1] and at the Factory Mutual Research Corporation (FMRC) [2], however, their potential usefulness for predicting the performance of real room fires has not been thoroughly explored. The IITRI technique requires a constant ratio of heat release rate to the volumetric rate of air inflow in order to maintain the same temperature distribution in the enclosure. The volumetric rate of air inflow, V, is proportional to wh3/2 [1] where w is the width of the doorway and h is its height. the ratios of the width of the doorway to the width of the room (W) and the height of the doorway to the height of the room (H) are kept invariant, then igh V2WH3/2. ᏙᎳᎻ The heat release rate, q, should be proportional to the floor area, w2, where the width of the room is equal to its depth. Thus, if If W. 2 1 2 floor scales as If it is assumed that the mass burning rate of a combustible wall is proportional to its area, then its heat release rate is proportional to w5/3 which violates the requirement that the heat release rate be proportional to w2. To summarize: when the horizontal dimensions of the prototype compartment are reduced by a scale factor, the IITRI modeling criteria require that the vertical dimension should be proportional to the scale factor raised to the two-thirds power and the rate of heat release be proportional to the square of the scale factor. Using this technique for non-combustible walls, IITRI found that the radiation flux, CO2 concentration, gas temperatures, and wall surface temperatures measured at several locations within the compartment were in fair agreement for both model and 10 x 10 x 8 foot room fires for model sizes as small as 1/8 scale. However, as seen above, the technique breaks down for combustible walls. FMRC approached the scaling problem from dimensional analysis considerations. Their findings indicate that the temperatures and gas compositions in a room scale reasonably well for geometrically similar enclosures where the heat release rates are proportional to the 5/2 power of the scale factor. This method assures that the ceilings of the model and the prototype are at geometrically similar points of the convection column generated by the flames. If it is again assumed that the burning rate of a combustible wall is proportional to its area, then it is proportional to w2 for geometric scaling, whereas, the burning rate required by the FMRC modeling is proportional to w5/2. This scaling method also fails to account for the contribution of combustible walls. The objectives of the present study are to determine the degree to which models can be used to scale the fire development in rooms with combustible linings, and to develop a procedure for predicting the potential for full fire involvement of a room based on measurements of the fire and thermal properties of the materials comprising the linings and the furnishings. This work is only in its initial stages. This paper describes some tests conducted in accordance with the IITRI scaling rules in a small enclosure which approximates a quarter scale model of a 9.5 x 10.5 x 7.9 foot burnout room. It compares the results of some corner tests in the model with those obtained from tests conducted in the full-scale room. It includes a preliminary examination of the effect of the gas flow rate and the location of the burner on the oxygen and temperature profiles in the small enclosure. The model has a 30 x 30 inch floor area, a ceiling height of 32 inches and a 6.8 x 27.4 inch doorway opening in the middle of one wall. The model enclosure consists of a steel shell with a non-combustible interior lining of one inch thick asbestos insulation board (36 lbs/ft3) (AIB). Several preliminary experiments with a gas burner at the center of the floor were conducted to assist in the selection, development and placement of adequate instrumentation to characterize the fire behavior in the model as well as to establish an overall energy balance. The latter not only contributes to an understanding of the fire behavior, but also checks on the accuracy of the measured data. |