The Reason Behind The Smell of LPG Cylinders That Helps Detect Leakage

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We are all familiar with the stench that turns up our noses as soon as there is any sort of leak from an LPG (Liquid Petroleum Gas) cylinder that we keep in our kitchen. It’s quite interesting to note, however, that LPG itself is actually odorless!

What is LPG?

Liquefied Petroleum Gas contains propane, propylene, butane, and butylene in a number of mixtures. It is completely odorless. LPG is made from refining petroleum or natural gas. The source is mostly restricted to fossil fuel sources. They are also extracted from petroleum or natural gas streams. The gas is kept liquid by using pressure and is transported via pressurized steel vessels.

The major uses of LPG are rural heating, cooking, motor fuel and refrigeration. LPG is one of the most convenient fuel sources for cooking and is also doesn’t hurt your wallet. North America, India, and some Brazilian urban areas are the major users of LPG. For heating, LPG has mostly been used in Europe as an alternative to electric heating and heating oil.

Environmentally LPG is a better alternative as well. It burns more cleanly than heavier molecular weight as it releases less particulate matter. It does, however, release carbon dioxide and some amount of carbon monoxide. The amount of carbon dioxide per kWh released by LPG is around 81% that of oil and 70% that of coal!

What gives LPG the odor?

LPG gas is basically propane and butane, and it is odorless in its natural state. The smell that you notice when there is a leak is actually of an entirely different agent, called Ethyl Mercaptan. This substance is added to the gas when it leaves the main storage terminals.


(Photo Credit : U. Vainio / Wikimedia Commons)

Ethyl Mercaptan, a.k.a, ethanethiol is a clear colorless liquid. It has an overpowering stench. Its vapors can irritate nose and mouth. It could even be lethal if swallowed or upon inhalation. But the amount added to LPG is safe and does not cause any issues.

As we all know, LPG is very dangerous, because if it leaks, it can cause terrible fires and devastating explosions. To avoid this, Ethyl Mercaptan is added to the gas, which possesses that strong odor of rotten cabbages. This smell helps us detect when there is a leak, which actually makes a lot of sense from a safety and security perspective. In fact, some people actually refer to the process of adding this foul-smelling substance as “stenching”.

Basically, it’s for your own good, so don’t complain next time you smell a bit of that odor in your kitchen.

Just be thankful it’s there in the first place!


  1. Indiana University
  2. Texas A&M University
  3. NOAA
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About the Author:

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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