What is the minimum size of the auxiliary drain valve for a trapped section of a wet fire protection pipe with a capacity of 10 gallons?

The minimum size of the auxiliary drain valve for a trapped section of a wet fire protection pipe with a capacity of 10 gallons is determined by the need to ensure adequate drainage without creating excessive pressure or flow restrictions.

A 3/4 inch valve is appropriate for this application as it strikes a balance between being large enough to accommodate the drainage of water from a 10-gallon pipe while also being manageable in size. This allows for a quick and efficient release of the trapped water during maintenance or system checks, which is critical for maintaining the integrity of the fire protection system.

Using a valve that is too small, such as a 1/2 inch valve, may lead to slow drainage, potentially causing water to remain trapped longer than necessary, which could risk freezing or other issues. Conversely, a valve that is too large, like a 2 inch valve, could create unnecessary complexity and cost without providing significant benefits relative to the drainage need from a 10-gallon volume.

In fire protection systems, it’s essential to follow codes and standards, which often dictate specific requirements for valve sizes based on pipe capacities to ensure effective performance and safety.