Combustible gases such as propane gas and methane gas are widely used in many homes and factories. However,
accidents caused by gas leakage become a menace to everyday life. Therefore, development of quick and highly
sensitive gas leakage sensor is required strongly. From these backgrounds, we have studied about plastic optical fiber
(POF) gas leakage sensor because the POF have many advantages such as low-cost, light weight, immunity to electromagnetic noise. In this paper, the POF sensing system for multi-point gas leakages and its long term stability have been studied. In the experiment, gas concentration below 1% was detected for both propane gas and methane gas. This operation does not depend on a light wavelength. So, using several LED light sources with different wavelength, the POF sensing
system for multi-point gas leakages was constructed. In the experiment using blue-, green- and red-LED, sensing of
three-point gas leakages could successfully be obtained. Further more, considering its system for real application, long
term stability of the sensor head was also checked and it was confirmed that the sensitivity does not change over 15 days.