Red Seal Gasfitter — Class A Practice Exam

What is the riser main in a gas system?

1. A horizontal gas line

2. A valve controlling gas flow

3. A vertical pipe that distributes gas to various floors or levels

4. A pressure regulator for different gas levels

The correct answer is: A vertical pipe that distributes gas to various floors or levels

The riser main in a gas system is a vertical pipe that serves the crucial function of distributing gas to various floors or levels within a building. This type of piping is essential in larger structures where gas needs to be supplied to multiple levels, ensuring that each floor has access to a consistent gas supply. The vertical design allows for efficient transport and distribution of gas upward, minimizing the number of horizontal runs needed and helping to maintain adequate pressure throughout the system. In many installations, risers also include features for safety and maintenance, such as isolation valves and access points for testing. Understanding the role of the riser main is essential for any gas fitter, as it directly relates to the overall efficiency and safety of a gas distribution system.