What does "1st 100' at 100PSI, add 2 lbs per 100'" refer to in fire management?

The phrase "1st 100' at 100PSI, add 2 lbs per 100'" specifically pertains to the pressure and flow calculations associated with water supply for firefighting operations. It indicates that the first 100 feet of hose requires a pressure of 100 PSI (pounds per square inch) to ensure adequate water flow, and for every additional 100 feet of hose beyond the first 100 feet, the pressure must increase by 2 PSI to maintain the required flow rate.

Understanding this is crucial for effective fire suppression, as pressure loss can significantly impact the water delivery to the fire. Properly managing water supply ensures that firefighters can effectively combat flames, control the fire, and protect property and lives. This formulation is essential for fire managers and operational personnel to ensure that they are providing sufficient pressure throughout the entirety of the hose layout when engaged in firefighting activities.