Did you know that propane-butane has no odor, but an Ethyl Mercaptan odorant is added to it so that any leaks can be detected easily?
The distinctive odor of propane-butane that people associate with it is actually added as a precaution. Ethyl Mercaptan is an odorant added to LPG and natural gas to give it a distinctive aroma. The process and the exact amount of flavoring added are closely monitored.
Industry has added Mercaptan to LPG and that is why propane-butane bottles smell stronger when they are almost empty. The flavoring is less volatile than the propane in which it is dissolved. Therefore, with the emptying of the bottle, the odor of Ethyl Mercaptan is felt more strongly.
Most people describe the smell of Ethyl Mercaptan as garlic, spoiled eggs or cabbage. Some people cannot smell the odourant and must rely on electronic leak sensors
An interesting fact is that flies like the smell of Ethyl Mercaptan. So if you notice that they are circulating around LPG bottles or appliances that use it, make sure there is no gas leaks and the cylinders are closed.