In the last decade,air pollution has become a major problem in metropolises.Therefor using alternatives for common fuels, especially gasoline was ordered. In a country like Iran with the second biggest natural gas resources in the world, CNG was the most important choice.This potential led to vast manufacture and usage of CNG consuming automobiles. Being used in different climates and areas and because of the susceptibility of natural gas,these automobiles have always been vulnerable in accidents.

Based on the statistics from reliable sources and scientific methodes,this research tries to present the order of importance of CNG fuel system parts in accidents.The results of this reaserch will reveal the priority of making the system parts safe.