- Author
- Ishii, H. | Ono, T. | Muroi, N. | Sato,F. | Kawano, T. | Megumi, H.
- Title
- Study of a Fire Behavior in a Miniature Simulation of a Cable Tunnel: From the Viewpoint of Fire Detection.
- Coporate
- Nihon Univ., Tokyo, Japan Hitachi Engineering Corp., Ibaraki, Japan Yamato Protec Corp., Osaka, Japan
- Journal
- Bulletin of Japan Association for Fire Science and Engineering, Vol. 40, No. 2, 9-18, 1991
- Keywords
- cables | tunnels | fire behavior | fire detection | telecommunications
- Abstract
- [ABSTRACT IN ENGLISH] Within today's advanced information society, it has become more and more important to prevent fires in cable tunnels where power cables and telecommunications cables are housed. Despite the existing technologies for fire-retardant treatments for cable sheathing, prevention of a cable tunnel fire is still a major issue because fire-retardant cables are quite expensive, because considerable time and money are required to replace the conventional cables with fire-retardant ones, and because considerable time and money are required to replace the conventional cables with fire-retardant ones, and because even fire-retardant cables can burn under certain conditions. The authors have made a miniature simulation of a cable tunnel carefully designed so that it reflects the conditions of an actual cable tunnel to study fire behavior in cable tunnels. The study clarified the following: (1) Polyethylene cables, which are highly combustible, generate a large quantity of dark smoke. When they burn in a tunnel, the temperature in the tunnel rises to more than 300 deg C. It is possible to forecast the rise of temperature and smoke density inside the tunnel by using an approximate function. (2) Fire-retardant vinyl cables are highly self-extinguishing even when they are forcibly ignited. As a result they hardly cause fire to spread. However, if these cables are loosely bundled so that air can flow among them, the cables could keep burning depending on the air flow speed. (3) With a bundle of both polyethylene cables and fire-retardant vinyl cables, the polyethylene cables keep burning if the air flow speed is more than 0.4 m/s, and the heat generated by the burning polyethylene cables helps the fire-retardant vinyl cables burn, causing the fire to spread. (4) Temperature sensors and smoke sensors are both effective in the detection of the early stages of a tunnel fire. However, temperature sensors, especially of the spread type, are more effective in locating the fire source. (5) The detection of a cable tunnel fire may be effectively carried out with a gas sensor for CO and/or H2 in addition to a temperature sensor and a smoke sensor.