What is a riser in the context of a gas piping system?

In the context of a gas piping system, a riser serves a critical role as a vertical pipe that supplies fuel gas. This design is essential for transporting gas vertically, typically from a lower level such as a basement or utility area to upper floors or different levels of a building. The riser system allows for efficient delivery of fuel gas to various appliances or fixtures throughout the structure that require it.

Understanding the specific function of a riser is key to ensuring that gas is distributed safely and effectively as it navigates different elevations within a building. This is particularly important in multi-story structures where appliances might be located on different floors. Thus, the riser's design not only facilitates functionality but also ensures compliance with safety regulations regarding gas installations.

In contrast, the other choices describe different components or functions within a gas piping system that do not pertain to the definition of a riser. Horizontal pipes serve to distribute gas laterally rather than vertically, a device that regulates gas pressure focuses on modulation rather than transportation, and a gas meter is associated with measuring gas flow rather than delivering it vertically within a building.