In which situation is the use of CNG considered hazardous?

The use of compressed natural gas (CNG) is considered hazardous in confined spaces without ventilation due to the risk of gas accumulation. In such environments, the potential for CNG to displace oxygen increases, which can create an asphyxiation hazard for individuals present. Additionally, since CNG is lighter than air, if it leaks in a confined area, it can accumulate at the ceiling level, increasing the risk of ignition if there is an ignition source present. Proper ventilation is essential to ensure that any leaking gas can dissipate safely into the atmosphere, minimizing the risk of an explosive atmosphere and ensuring that oxygen levels remain safe for breathing.

In contrast, outdoor settings and routine maintenance checks typically provide adequate ventilation, thereby reducing the potential hazards associated with gas accumulation. While storing CNG in high-pressure tanks requires careful handling due to the risk of leaks or ruptures, the primary concern related to hazardous conditions arises when the gas is confined without adequate airflow.