#mercaptan

[ilearnedthistodaysblog]

#1090 Why do they add a smell to gas?

Why do they add a smell to gas? Gas companies add an additive called mercaptan to natural gas so that people can smell it in the event of a gas leak. The natural gas we use to cook with or to heat our houses and our water doesn’t smell of anything. Natural gas contains many different compounds, but the largest component of natural gas is methane and methane doesn’t smell of anything. Some gases have a very strong smell and some gases don’t smell of anything. This all comes down to our ability to smell and not the gas itself. We have odor receptors in our noses and we are only able to smell molecules that can attach to these odor receptors. Methane is a very light gas and it does not attach to the odor receptors. Research has shown that we are generally able to smell gases that are 15 times heavier than hydrogen and we are unable to smell gases that are lighter. One of the reasons for this could be evolution. Many of the gases that we think smell bad are a signal to us that the source of them is toxic, such as a decaying body, or an open sewer. We might have evolved to be able to smell these gases to keep us safe. What actually is “natural” gas? Isn’t all gas natural? Natural gas was named in the 1800s and it was called “natural” gas to distinguish it from coal gas, which was made by heating coal. Natural gas came out of the ground naturally and coal gas had to be manufactured. After a while, we pretty much stopped using coal gas and natural gas was the only one left, but the name stuck. These days, a lot of people think the name should be changed because “natural” makes it sound as though the gas is safe, but it is still a fossil fuel and is a huge contributor to climate change. Natural gas is formed in the same way as oil. Millions of years ago, plants and animals died and sank to the bottom of the sea. They became buried under sand, dirt, and rock, and the pressure and heat began to build up. Over millions of years, the pressure squashed all of this organic material and left coal or oil. When coal and oil are formed, gas is also released. Oil and coal tend to stay where they are, unless they are drive upwards by the moving plates and seismic activity. Gas is often found with the coal and oil, but, because it is lighter, it rises up and gets trapped in pores and pockets in the ground. When the gas comes out of the ground it is called wet natural gas because it contains a lot of compounds, including water vapor. It is sent to a processing plant to have most of these removed before it is shipped or piped for use. Natural gas has many uses, such as power generation or cooking at home, because it is highly flammable. This is the reason why an odor has been added to it. Because natural gas is colorless and odorless, if there is a leak in a gas pipe, it can build up to dangerous levels and nobody will be able to see it or smell it. When the gas has reached a high enough density, any ignition source can cause it to combust explosively. This is what happened in the New London School in 1937. An odor has first been given to gas in Germany in the 1880s, but it didn’t catch on because it was time consuming and natural gas wasn’t as widespread as it became. It took the New London School disaster to make it go worldwide. The New London School was a school in Texas, USA. The school was built in 1932, which was right in the middle of the Great Depression, but the town it was in was wealthy due to oil discoveries. With the huge quantities of oil discovered were obviously huge quantities of natural gas. The architects of the school wanted to fit a boiler to heat it, but the school board overrode the architect and went for 72 gas powered heaters throughout the building. Gas leaked out of some of the pipes and steadily built up in the basement under the school. There was no way of detecting the buildup, although many students had complained of headaches. On March 18th, 1937, a teacher turned on an electric sander which ignited the gas. The school was destroyed and 300 teachers and students were killed. A lot of changes were made in the aftermath of this disaster, but the largest one that remains with us was the decision to add an additive to the natural gas so that people could smell it. A compound called mercaptan was added to the gas straight away. It has a very strong sulfurous smell, like rotten eggs. We have evolved to be able to smell sulfur for the reasons I mentioned earlier. Sulfur sends us a strong warning signal. Once the US began to add an odor to gas, it very quickly spread around the world. The odor is added by having tanks of mercaptan at the processing plant. Each tank is attached to a pipe and they drop drops of the chemical into the gas as it flows past along the pipes. That is enough to give it its odor. And this is what I learned today.  Photo by Pixabay: https://www.pexels.com/photo/burning-stove-266896/ Sources https://www.thenakedscientists.com/articles/questions/why-can-you-smell-some-gases-not-others https://www.reddit.com/r/explainlikeimfive/comments/buk2yo/eli5_why_do_some_gasses_have_an_odour_while/ https://indianapublicmedia.org/amomentofscience/gas-odorless.php https://www.peoples-gas.com/all-about-gas/safety/smell https://en.wikipedia.org/wiki/New_London_School_explosion https://en.wikipedia.org/wiki/Natural_gas https://en.wikipedia.org/wiki/Natural_gas Read the full article

[davekatzdefensesquad]

something I learned yesterday from a spn/911 lonestar crossover fic. gas companies inject the sulfur smell into gas so you can smell a leak and get out. that's so freakin' smart.

[q2technologies]

Mercaptans occur in all fractions from methane and heavier, but cannot be removed by distillation because of which it requires proper chemical treatment for mercaptan removal. The amount generally ranges from a few ppm to several thousand ppm. 

[truground]

This Day in Environmental History – On March 18, 1937 at 3:17 pm, a natural gas leak caused a massive explosion at a school in New London, Texas that killed 298 students and teachers with another 300 suffering serious injury. It is stilled considered the deadliest school accident in US history. The leak went undetected due to natural gas being both invisible and odorless. Following the disaster, governments both in the US and around the world began mandating that a chemical called mercaptan be added to natural gas, which would provide for a strong odor (rotten eggs smell) that could be easily detected by humans. A young reporter named Walter Cronkite covered the event that day on one of his first assignments. In 1996, he was quoted as saying, "I did nothing in my studies nor in my life to prepare me for a story of the magnitude of that New London tragedy, nor has any story since that awful day equaled it.”

[gordonanderson23]

Ethyl mercaptan is a clear liquid with a distinct odor. It is an organosulfur compound with the formula CH3CH2SH. Abbreviated EtSH, it consists of an ethyl group (Et), CH3CH2, attached to a thiol group, SH. Its structure parallels that of ethanol, but with S instead of O. The odor of EtSH is infamous. Ethyl mercaptan is more volatile than ethanol due to a diminished ability to engage in hydrogen bonding. Ethyl mercaptan is toxic. It occurs naturally as a minor component of petroleum, and may be added to otherwise odorless gaseous products such as liquefied petroleum gas (LPG) to help warn of gas leaks. At these concentrations, ethyl mercaptan is not harmful. The market research report analyzes the Global Ethyl Mercaptan Market after carrying out different intellectual and extensive analysis on the Ethyl Mercaptan industry. To gain a better understanding, vision, and assets of the market segments, the research report helps the leading vendors, suppliers, maufacturers, end-users, and distributors.The Ethyl Mercaptan report covers some of the major regions, including North America, Europe and Asia-Pacific, South America, Middle East and Africa.

[poetry-in-potion]

The Smell of Danger

Did you know that the gas we use on daily basis for cooking and heating purposes, the LPG gas, is actually – odorless? Nooo, but I know its smell, you might argue, it is so immediately recognizable, in fact, everyone knows it. You might enter someone’s apartment and say, in a second: I smell a gas leak.

Well, yes and no. Both LPG (which is propane and butane) and natural gas (methane) are in their natural state simply – odorless. What you smell, what you do detect so clearly, is the smell of a DELIBERATELY added agent called ethyl mercaptan or ethanethiol. This substance is a clear and TOXIC liquid with a distinct and infamous odor, which humans can detect in minute concentrations, less than one part per million. Its smell resembles that of “leeks, onions, durian”, says Wikipedia, but to most people it simply smells as either smelly socks, rotten eggs or rotten cabbage. How lovely.

So how did this whole nasty-smell business start? According to one source, during the early 1800s and the initial stages of the gas industry in Europe, something called “town gas” was used for lighting and heating. It contained mostly hydrogen and carbon monoxide and was therefore poisonous. Fortunately, however, it also contained sulfur compounds, which gave it a “gassy odor” – if there ever was a leak it was quite smellable. But the first deliberate gas odorization occurred much later, in Germany during the 1880s: the aforementioned ethyl mercaptan was added to water gas to intentionally reproduce the gassy odor previously associated with town gas, making it easily detectable.

Wikipedia claims that it all happened much later. In 1938 the employees of the Union Oil Company of California were the first to spot turkey vultures gathering at the site of any gas leak. After finding that this was caused by traces of ethanethiol in the gas, it was decided to boost its amount in the gas, to make detections of leaks easier. This was a simple and clever way to alert people of the very serious safety hazard they might find themselves in.

Be that as it may: nowadays ethyl mercaptan is simply added to the gas when it leaves the main storage terminals, before it’s delivered to customers. How much of it: according to some sources, it is customary to inject some 1.0-1.5 lbs (less than a kilogram) of ethyl mercaptan per 10,000 gallons of liquid LPG gas. At these concentrations, ethanethiol is not harmful.

I don’t know about you, but I actually do not find the “smell of gas”, i.e. of ethyl mercaptan, that disgusting, especially in small doses and fragrant hints. “Unbearable” would be a better adjective, but, then again, that’s the whole point. You are meant to run before you get to smell it well.

More on this topic HERE (by Luca Turin) and HERE. 

Images are from HERE, HERE and HERE. 

[mentaldefenestration]

How writing works

Me trying to write voluntarily: Uh...character A and character B.....talk about....things... Me trying to study for a lab final: *brain bashes me over the head with a plot bunny, I wake up an hour and a half later having written a thousand words of romantic fluff about video game characters* WHY?!?

[labphoto]

Ethyl mercaptan, the compound that probably has the most awful odor currently in the lab.

Ethanthiol is a colorless gas or clear liquid with a boiling point 35°C. It is an organosulfur compound with the formula CH3CH2SH. It is often added to otherwise odorless gaseous products such as methane, ethane or liquefied petroleum gas (LPG) to help warn of gas leaks.