What is the required pressure at the top of the standpipe?

The required pressure at the top of the standpipe is determined by the need to ensure adequate water flow and pressure for firefighting operations. A pressure of 100 psi at the top of the standpipe is specified to facilitate effective operation of fire hoses and ensure that water can reach the necessary height to fight fires effectively. This pressure level is standard in many building codes and fire protection regulations, as it balances the need for sufficient pressure to deliver water while not exceeding what can be safely managed by the system's components. In practice, having 100 psi at the top ensures that when hoses are deployed, the firefighters have the necessary water supply even under peak demand conditions. This pressure also accounts for potential losses in the system due to friction, height, and other factors that can reduce effective pressure at the nozzles during use.