What is the minimum pipe size required for Class I and III standpipes?

For Class I and III standpipes, the minimum pipe size required is 4 inches. This requirement is based on the need to provide sufficient flow capacity for firefighting operations. Class I standpipes are designed for use by trained firefighters or personnel, providing a means to connect fire hoses to deliver water directly to the fire area. Class III standpipes serve both trained firefighters and the general public, allowing for both hose connections and hose storage.

Choosing 4 inches as the minimum size ensures that the system can deliver an adequate volume of water quickly and effectively. Smaller pipe sizes, such as 2 or 3 inches, would not be able to maintain the necessary water flow rates required to combat fires, especially in larger structures or scenarios requiring substantial firefighting efforts. A 6-inch pipe could be used in certain situations for greater flow capacity, but it is not the minimum requirement. Thus, 4 inches balances the need for effective fire response while adhering to safety standards and regulations.