What is the pressure requirement for a Standpipe system and Siamese connection?

The pressure requirement for a standpipe system and Siamese connection is based on the need to effectively deliver water to various floors of a building or to the fire scene. Adding 25 psi is considered a standard calculation to ensure that there is sufficient pressure available to overcome the friction loss in the hoses and the elevation gain when water must be delivered vertically.

In the context of firefighting and standpipe systems, it's essential to achieve a specific pressure at the most demanding outlet, especially considering the height and layout of structures where these systems are deployed. The 25 psi is generally used because it accommodates the hydraulic losses that would otherwise affect the water flow and firefighting effectiveness.

Understanding the standard of adding 25 psi directly helps fire engineers assess the pressure needed when planning hose lines, ensuring that crews maintaining adequate water delivery to suppress fires effectively, particularly in high-rise buildings where elevation can significantly impact water pressure.