Experimental results are presented of the piloted ignition delay time and the upward flame-spread rate over the surfaces of insulated electrical cables under an externally applied radiant flux. The objective of the experiments was to assess and rank the fire performance of seven types of complex cables commonly used in electrical installations. The experiments were carried out with 46 em long single cables that were suspended vertically and exposed to irradiance levels ranging from 0.5 -2.5 W/cm 2 • Some of the cables had a conducting core, and some did not. A simplified analysis, similar to that developed by Quintiere and coworkers was developed to indentify the parameters that dominate the fire characteristics of the cable. A method similar to that proposed by the above authors was applied to develop flammability diagrams and to define the flame spread properties of the cable materials in an attempt to assess and rank the fire performance of the seven types of cable. It is shown that the method can be successfully applied and that it provides a simple way to rank the cables and to calculate the parameters important to ignition and flame spread in electrical cables. The study also explores the feasibility of predicting the piloted ignition performance of the cable insulations using thermogravimetric analysis (TGA) data in conjunction with the ignition and flame spread formulas by proposing that the surface temperature at which thermal degradation produces pryolyzate is related to the ignition temperature for that particular material. The predicted ignition delay times are compared with experimental results and it is shown that for most polymers, the temperature at which thermal degradation is first Observed can be used to estimate ignition delay times, particularly at high irradiance levels.
Both the FRD and ORNL determined that the only way to obtain conclusive results and to accurately analyze the fire performance of the ventilation system, fire protection system, prefilters/HEPA filter array, FRP VOG duct, etc. was to design and conduct a full scale fire test series. In order to design and construct a representative test article, we had to gain an accurate and detailed understanding of the actual facility layout, fire protection systems, facility operating procedures, and ventilation system and operation. FRD personnel toured Bldg. 7920 to obtain first hand insight into its configuration and operational parameters. " However, since most of the significant areas were inaccessible, we spent a significant amount of time studying photos, building plans, facility SAR, and talking to knowledgeable ,, people. Through numerous phone calls and facsimile transmissions to ORNL and Lockwood Greene, we were able to complete these tasks and began developing a detailed test design. The majority of our questions were answered and information provided by personnel from Lockwood Greene. Although general information was available from other sources, detail and historic questions were answered by Lockwood Greene. In fact, Lockwood Greene provided a great deal of help in developing the prel!minary fire test matrix included as Table 4. BUILDING 7920 FACILITY DESCRIPTION As it turned out, NJ Alvares in his report [1] provided a good general facility description summary. It is, therefore, presented below: Facility Specifications "Figure N-1 is a plan view of the transuranium processing plant showing both office and operator's areas, and an isometric drawing of a typical cell in the operations area of the building. The shielded cell bank contains nine 7 ft. wide hot cells each with a 7 ft. long cubicle area, separated from each other by 2.0 ft. minimum thick concrete walls. Seven cells contain a tank pit area (9 x 22 ft. high). An inter-cell conveyor housing and the cellventilation exhaust duct run through the cubicle pits the full length of the cell bank. • "In the first seven cells air enters the south wall of the tank pit through a duct (10 in. diameter), the centerline of which is 21 ft. above the floor. The air exits the north wall of , the tank pit to the cubicle pit through a slot (2 x 4 ft.) ten feet above the cell floor and is drawn into a cell ventilation duct (20 x 40 in.) through an opening (17.5 in. diameter) located 8.5 ft. above the cell floor. "In the last two cells air enters the cubicle pit through a similar duct only 2' above the pit floor and exits to a cell ventilation duct. A waste-tank pit behind the last two cells and below the first-floor level is connected to each of the last two cubicle pits through a 2 ft 5
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