Analysis and design of an improved light interference methane sensor

The light interference methane sensor has many advantages except inconvenient reading and no communication with monitoring system. To improve it, many systems have been reported, but which are too big in size to use in practice. In this paper, we analyzed the reason for the big size and proposed two optical configurations to reduce the system size. Based on the one-to-one relationship between the output of the photosensitive element and the methane volume fraction, we redesigned two types of chambers taking up most room of the optical configuration. The one with the rectangular cross section was only for measuring the low methane volume fraction, and the other one with the trapezoid cross section for both low and high methane volume fraction. The feasibility of the design method is verified by the simulation. We showed the manufactured optical configuration compared to the original, and the new designed optical configuration is less than half size of the original. The experiments showed that the maximum measuring error of the calibrated sensor with the designed optical configuration was ±0.01%.