What is a key factor in determining the GPM flow for fire protection systems?

In fire protection systems, the gallons per minute (GPM) flow is heavily influenced by the nozzle and lines in use. This is because different nozzles are designed to deliver specific flow rates and patterns depending on the type of fire, required reach, and operational needs. The design of the hose lines, including their diameter and length, also significantly affects the amount of water that can flow through them, as friction loss can reduce the effective flow at the nozzle. Therefore, understanding the properties and specifications of the nozzles and hose lines allows firefighters to calculate the necessary GPM to effectively suppress the fire.

Factors such as the type of fire being extinguished, although relevant to the overall strategy and tactics used, do not directly determine the flow rate of water being discharged. The size of the pump is crucial for ensuring there is sufficient pressure and volume, but the pump's capacity must be matched with nozzles and hoses appropriately to achieve the desired GPM. Water temperature can impact the physical characteristics of water, but it does not significantly influence the flow rate for fire protection systems compared to the design and configuration of the nozzle and hoses used in the delivery system.