Why is Ethyl Mercaptan a crucial addition to propane?

Ethyl mercaptan is added to propane primarily for safety reasons. As a colorless and odorless gas, propane in its natural state poses significant risks because leaks can go undetected. Ethyl mercaptan has a distinct and unpleasant odor, often described as similar to rotten eggs, which serves as a warning signal to users. This odor allows individuals to detect even the smallest leaks, prompting a swift response to mitigate the risk of fire or explosion. By ensuring users can smell the gas, ethyl mercaptan plays an essential role in preventing accidents associated with propane use.

The other options do not relate to the primary function of ethyl mercaptan. It does not have properties that directly increase pressure, provide pest deterrence, or enhance flame quality. Thus, its main purpose is indeed to alert users to potential gas leaks, ensuring safe handling and usage of propane.