Gas Fitter Practice Test

What substance is commonly added to natural gas to give it an odor?

1. Propane

2. Ethanol

3. Mercaptan

4. H2O

The correct answer is: Mercaptan

Natural gas is odorless in its natural state, making it challenging to detect leaks, which can pose serious safety risks. To address this issue, an odorant is added to the gas for safety purposes. Mercaptan, a sulfur-containing compound, is commonly used as this odorant because it has a distinctive smell often described as resembling rotten eggs. This strong odor allows consumers to easily identify the presence of gas leaks, ensuring that they can take action to address the situation promptly. Other substances such as propane and ethanol are not used specifically for marking natural gas leaks, as their primary purposes lie elsewhere in the energy sector or as fuels. Water (H2O) does not serve the function of odor enhancement and is instead a byproduct in some gas combustion processes. Thus, the inclusion of mercaptan as the odorant for natural gas emphasizes safety and leak detection.