What is the main drain size for risers up to 2 inches in size?

The main drain size for risers up to 2 inches in size being ¾ inch is based on the established standards for plumbing and sprinkler system design. In these systems, the main drain is responsible for removing water from the riser and must be appropriately sized to ensure efficient drainage without causing any blockages or pressure issues.

Using a ¾ inch drain for risers up to 2 inches strikes a balance between adequate flow capacity and maintaining the structural integrity of the plumbing system. The size allows for the effective drainage of water while minimizing potential issues like water velocity problems that could arise with a drain that is either too large or too small relative to the riser size.

This sizing is typically guided by codes and best practices in the industry, which have been designed to optimize performance and safety in fire protection systems. Proper drain sizing is crucial to prevent water hammer, backflow, or other unwanted hydraulic phenomena that could compromise the system's functionality.