The maximum flow capability for Class I and Class III standpipes for unsprinklered buildings is _____________ gpm.

The maximum flow capability for Class I and Class III standpipes in unsprinklered buildings is correctly established at 1250 gallons per minute (gpm). This standard is outlined in the National Fire Protection Association (NFPA) regulations, specifically NFPA 14, which governs the installation of standpipe and hose systems.

According to NFPA guidelines, Class I standpipes are intended for use by firefighters and trained personnel, providing a reliable source of water for firefighting efforts. Class III standpipes serve a dual purpose, supporting both firefighter operations and providing hoses for use by building occupants. In the case of unsprinklered buildings, the higher flow rate of 1250 gpm is necessary to ensure effective suppression of fires, as these structures lack the additional fire control measures that sprinklers would provide. This elevated flow capacity is critical in maintaining fire safety and ensuring that sufficient water is available quickly during an emergency response.

The other flow capabilities listed—250 gpm, 500 gpm, and 1000 gpm—are insufficient for the demands of firefighting in unsprinklered buildings, where rapid and effective water delivery is essential to control potentially dangerous fire situations.