On wet systems, if a trapped section of pipe holds less than how many gallons, the auxiliary drain must consist of a valve not smaller than 1/2 inch?

In wet fire sprinkler systems, an auxiliary drain is necessary to facilitate the drainage of any trapped water that could potentially freeze, causing damage to the system. The specific requirement that the auxiliary drain must consist of a valve not smaller than 1/2 inch applies when a trapped section of pipe holds less than 5 gallons. This standard ensures that even if only a small volume of water is trapped, it can be adequately drained to prevent issues related to freezing or stagnant water.

A trapped section of pipe with less than 5 gallons is a critical consideration in the design and maintenance of wet systems. The specification of a 1/2 inch valve allows for efficient drainage while also balancing the need for system integrity and hydraulics. Using a valve that is too small could hinder the drainage process, leading to complications if water does not drain properly.

This requirement reflects a balance between practicality and safety, ensuring that the system functions effectively without the risks associated with trapped water. Understanding the specific gallon threshold is crucial for compliance with fire safety regulations, as well as for effective sprinkler system design and operation.