What is natural gas odorization? Why do we odorize? What is the difference between an odorant, an odorizer, and odorization?
The Problem: Natural Gas is Odorless
Natural gas by itself is odorless and explosive, a fatal combination. One of the worst tragedies in the United States involved a gas leak at a London, Texas school in 1937. In that situation, the non-odorized gas ignited, and the explosion took over 200 students’ and teachers’ lives.
The Solution: Odorize Gas
The New London School explosion became the impetus to odorize natural gas in Texas and other states. Today, the federal U.S. government mandates that any combustible gas in a distribution pipeline must contain an odorant so that if the gas is present at 1/5 of the lower explosive limit, a person can detect it assuming they have a “normal sense of smell.” The regulations also require that beginning in 1977, transmission lines in Class 3 and Class 4 locations must also contain the same odorant level. Of course, there are some exceptions to this regulation, and they are in the rules at 49 CFR 192.625.
Most do not realize that odorization is the first line of defense against odorless and combustible gases.
What is an Odorant versus Odorizer?
The odorant is the chemical injected into the gas to deliver the rotten-egg odor. Over many years, a class of organosulfur compounds known as mercaptans and some non-sulfur compounds became the standard chemicals to odorize natural gas.
What is odorization of natural gas?
Gas odorization is the process of injecting an odorant into a gas stream by an odorizer or odorant injection equipment. The purpose, of course, is to make the gas smell so that one can detect it because, in its natural state, natural gas is odorless. Natural gas odorization is the first line of defense against a naturally combustible and odorless gas. The smell causes people to react to a gas leak to get to a safe place and call 911.
What mercaptan is in natural gas?
While the odorant often contains mercaptan, it is not always the case. The odorant is typically a blend of various organosulfur or non-sulfur compounds. It is customary that odorants for natural gas may include tertiary butyl mercaptan, tetrahydrothiophene, isopropyl mercaptan, dimethyl sulfide, and methyl ethyl sulfide.
What is the smell in gas?
Natural gas in its native state is odorless. The odorant, which may contain sulfur compounds, is added to natural gas to give off a distinctive foul odor often described as rotten eggs or hydrogen sulfide.
Who put the smell in natural gas?
Gas companies distributing gas to end-users have their gas lines odorized to assure safety. Natural gas odorizers inject the odorant into gas. Odorizing distribution gas lines gained widespread acceptance after an accident in a Texas school in 1927 caused the deaths of nearly 300 people.