ABSTRACT
Many lives and facilities have been lost in fires. Especially, elderly, toddlers, and babies are affected the most. In Japan, the number of people older than 65 years who died in fires reached 53% in 2004, and the number of persons older than 81 years went to 20%. An elderly person takes more time to sense fire and also to evacuate to safe places. Although it is important to prevent the fire, it is also very important to report the fire as early as possible. Human sense decreases with age and it is difficult to perceive the fire at an early stage. It is desired to develop a highly sensitive element for fire and its system that can detect fire at an early stage. Many fires are smoldering fire. Therefore, it was attempted to detect a smoldering fire, which was mainly caused by a cigarette in a general house. In this chapter, same types of eight sensors are
used to detect the fire. The sensor is a type of a tin oxide gas sensor, which is used to detect various kinds of reducing gases. It is sold on the market as a gas detector. The sensor is mounted on a supporting bar and its height can be changed. The height was set at 50, 100, and 150 cm in the experiment. The burning cigarette was put on a cotton cloth and the generated gases were detected. The cloth was used as a subjective material for the fire. The sensor output near the fire source fluctuates largely. It was attempted to identify the position and burning material of the fire. The moving average characteristics of the sensor outputs were derived and the differential characteristic of the sensor output was also derived. The characteristics are effective in identifying the fire position. The scattering diagram for two sensor outputs near the fire source was introduced and the slope of the characteristic was derived. The slope is effective in distinguishing the material of fire source. The position of the fire and the material that caused the fire could be identified in about 30 s. Tin oxide gas sensor is good for detecting the smoldering fire.
