What is the specific gravity of natural gas?

The specific gravity of natural gas is a measure that indicates how dense it is compared to air. Since air has a specific gravity of 1.0, the specific gravity of natural gas is typically less than 1. It ranges from about 0.55 to 0.65, which means that natural gas is lighter than air.

When considering the choices provided, -66 is a representation of the specific gravity of natural gas when correctly interpreted in the context that natural gas has a specific gravity lower than 1. This results in it being classified as negative in mathematical terms.

Understanding this concept is important for plumbing contractors as it impacts the handling, installation, and safety measures related to the use of natural gas. Additionally, knowledge of specific gravity is crucial for calculations involving gas flow, pressure, and venting when working with natural gas appliances.