For Class 1 and Class 3 structures, the water supply should provide how many gallons per minute (GPM) for 30 minutes at 65 PSI?

To determine the water supply requirements for Class 1 and Class 3 structures, it's essential to consider the standards set by fire protection authorities regarding fire flow calculations. Class 1 and Class 3 structures typically require substantial water flow to effectively suppress fires, particularly if they contain materials or configurations that can contribute to a fire's intensity or spread.

In this case, the standard specifies a minimum flow rate of 500 gallons per minute (GPM) for a duration of 30 minutes at a pressure of 65 PSI. This flow rate is crucial because it ensures that firefighters have a sufficient water supply to combat a fire effectively during the initial response phase, which can significantly impact the potential for fire spread and overall property protection.

The requirement for 500 GPM aligns with established fire codes and guidelines, which are based on the recognition that high-capacity water supply is necessary for effective firefighting operations in these classes of buildings. This flow rate not only supports the firefighting efforts but also helps to maintain adequate pressure throughout the operation, which is critical in delivering water to fire hoses and ensuring proper functioning of firefighting equipment.