What is the required size for class 2 standpipes that are over 50 feet?

In fire protection systems, the size of standpipes is crucial for ensuring adequate water flow to suppress fires effectively. Class 2 standpipes are designed to serve the needs of personnel on the scene who are often first responders or trained firefighters, utilizing hose connections primarily for hand line use.

For standpipes that are over 50 feet in height, the National Fire Protection Association (NFPA) codes typically mandate that the diameter of the standpipe should be 2.5 inches. This size is optimal because it balances the need for sufficient water flow and pressure while also ensuring that hoses can be easily managed by trained personnel. A 2.5-inch diameter allows for enough water to be delivered rapidly while minimizing the resistance and potential losses that come from smaller pipe sizes.

Larger diameters, such as 3 inches or 4 inches, might be used in different contexts, such as Class 1 standpipes or for other types of systems, but for Class 2 standpipes over 50 feet, 2.5 inches is specified as the standard to ensure effectiveness in fighting fires on upper floors.