What size of auxiliary drain is required for trapped water over 50 gallons?

The requirement for an auxiliary drain size when dealing with trapped water over 50 gallons is determined by the need for effective drainage and maintenance of the system. An auxiliary drain serves as a means to remove accumulated water from the sprinkler system, ensuring that this water does not become stagnant and negatively impact system performance or lead to other issues such as corrosion or water hammer.

A drain size of no less than 1 inch is specified for trapped water in this volume because larger diameters facilitate faster drainage. This is crucial for maintaining system integrity and preventing potential pressure build-up that could harm the piping or sprinkler components. In addition, a larger drain allows for a sufficient flow rate, minimizing the time water remains trapped and contributing to a more reliable overall sprinkler system operation.

While smaller drain sizes might be adequate for lesser quantities of accumulated water, they may not provide the same efficiency for larger volumes, which is why the 1-inch size is the minimum requirement for situations where there is over 50 gallons of trapped water. This guidelines align with plumbing and fire protection codes to ensure the safety and efficacy of sprinkler systems.