Odorants are chemical compounds that are added to natural gas to give it a distinctive smell, making it easier to detect leaks. The most commonly used odorant for natural gas is called mercaptan, which has a strong sulfur odor. However, there are other types of odorants available, including THT (tetrahydrothiophene) and non-sulfur odorants.

THT is a cyclic sulfide that has been used as an odorant for natural gas since the 1950s. It has a lower odor threshold than mercaptan, which means that it can be detected at lower concentrations. THT is also less corrosive than mercaptan, which can be beneficial for certain applications. However, THT has a slightly different odor profile than mercaptan, which can make it more difficult to detect in some situations.

Non-sulfur odorants are a newer class of odorants that have been developed in recent years. These odorants do not contain sulfur, which can be beneficial for applications where sulfur compounds are not desired. One example of a non-sulfur odorant is carboxylic acid, which has a distinct, pungent odor. Non-sulfur odorants can be more expensive than traditional sulfur-based odorants, but they may be preferred in certain situations.

In addition to THT and non-sulfur odorants, there are other odorants that have been used for natural gas in the past. One example is ethyl mercaptan, which was commonly used in the United States until the 1960s. However, ethyl mercaptan has a higher odor threshold than other odorants, which can make it less effective at detecting leaks.

Overall, odorants are an important component of natural gas distribution systems. They help to ensure that leaks can be detected quickly and easily, which is critical for safety. While sulfur-based odorants like mercaptan are the most commonly used, there are other options available, including THT and sulfur-free odorants, that may be preferred for certain applications.