What does specific gravity measure?

Specific gravity is a dimensionless quantity that measures the weight of a substance compared to the weight of a reference substance, typically water for liquids and air for gases. This means that it provides a means to assess how dense or heavy a substance is in relation to another, which is often crucial in fields such as chemistry, physics, and engineering.

In the context of gas applications, knowing the specific gravity helps in understanding how a gas will behave in the presence of air or other gases, which is essential for safe handling and storage. For example, if a gas has a specific gravity greater than one, it is heavier than air and will tend to accumulate in low areas, whereas a gas with a specific gravity less than one is lighter than air and will rise.

The focus on weight in comparison with water or air also makes it a useful parameter in the calculation of buoyancy and the design of containment systems. Understanding specific gravity is particularly important in industries that use liquefied petroleum gases (LPG), as it affects storage, transport, and safety measures.