Journeyman Plumber Practice Exam

A gallon is a standard unit of volume used in the United States and is equal to 231 cubic inches. This conversion is based on the definitions used in the imperial system, where 1 gallon is defined to contain precisely 231 cubic inches. Understanding this relationship can be essential for plumbing calculations that involve fluid volumes, such as determining how much water a particular tank can hold or how to properly size piping for water transport.

The other figures mentioned—128, 256, and 512—are not accurate representations of a gallon’s volume in cubic inches and don't correspond to the established conversions used in the industry. Familiarity with these conversions is fundamental for plumbers as they often work with different units of measurement while planning and executing their tasks.