LPG is colourless, odourless and heavier than air. It has a high heating or caloric value that allows it produce more heat in a short lifetime. It is a clean-burning fuel which is usually sold in cylinders of different sizes in liquid form. So, it is a portable, convenient energy source that is easy to store, use and transport. The unpleasant smell of the LPG is due to the presence of an odorant which is added to LPG for safety reasons.