From water gas to natural gas, the addition of an odorant to gas, or gas odorization has always been driven by the desire to keep people safe.
Town Gas Naturally Reeks
In Europe, during the early 1800s and the initial stages of the gas industry, town gas was manufactured for lighting and heating. This gas was produced from the carbonization of coal and contained mostly hydrogen and carbon monoxide and was obviously poisonous. The gas also contained sulfur compounds and innately had a gassy odor so that if there ever was a leak it was perceived through the sense of smell.
First Odorized Gas
The first odorization (i.e. adding an odorant to gas so that it is detectable by smell), occurred in Germany during the 1880s. In that situation, Von Quaglio added ethyl mercaptan to water gas to intentionally reproduce the gassy odor associated with town gas to make it detectable.
Tragically, however, the New London Texas disaster was the impetus to widespread odorization.
London School Explosion
The New London Texas economy was boosted in 1930 through an oil find in Rusk County. As a result, the London School was built in 1932 at a cost of $1 million dollars and considered a modern steel-framed building. In 1937, the New London Texas school board decided to cut costs by dropping their contract with United Gas Company. With approval from the superintendent, plumbers tapped a residue gas line from a local oil company to use the green or wet gas. The oil companies typically would flare off this waste gas. Using the waste gas, however, became a common money-saving practice for buildings on the oilfield at that time, although the oil companies did not explicitly authorized its use.
Apparently, the odorless and undetectable natural gas leaked from the connection of the residue line and made its way into the crawlspace which ran the length of the school. The gas built up until a spark ignited the gas and the explosion left behind a collapsed building and as many as 295 deaths.
As a result of the disaster, both the United States and Canada began regulating the use of odorants in gas. The current US regulation is 49CFR, 192.625, “Odorization of Gas.” It mandates that any combustible gas within a distribution line and transmission line (exceptions noted in the rules) must contain odorant at the level of 20% (1/5) of the lower explosive limit so that a person with a “typical” sense of smell can detect it. To read the current regulations we have posted them at What are the Natural Gas Odorization Regulations?