What is the maximum number of 90-degree elbows allowed in a vertical pipe when installing a main vent system?

The maximum number of 90-degree elbows allowed in a vertical pipe when installing a main vent system is two. This is based on code requirements, which aim to ensure effective airflow and minimize resistance in ventilation systems.

Using more than two 90-degree elbows can lead to significant airflow restrictions, causing potential issues with the venting system, such as inadequate venting pressure, which could affect the system's overall performance. Limiting the number of elbows not only facilitates smoother airflow but also helps maintain the system’s efficiency and effectiveness in preventing gas buildup within vents.

In practice, minimizing bends in vertical pipes enhances the system's ability to expel gases safely and effectively, aligning with best practices and regulatory standards.