What pressure is typically used to start a relay pumping operation?

In relay pumping operations, the typical pressure used to initiate the system is around 125 PSI. This pressure is considered optimal because it provides a sufficient force to effectively transfer water over long distances, which is necessary when multiple fire engines are working together in a relay.

The 125 PSI level helps ensure that water can reach the needed pressure at the receiving engine while also taking into account potential friction loss over distance, especially in large hose lines or when water must be pumped uphill. This pressure is a standard used by many fire departments and is effective at maintaining the necessary flow rates required to combat fires while keeping safety and equipment durability in mind.

Choosing a pressure below this, such as 50 or 100 PSI, may not provide adequate flow, while a significantly higher pressure like 150 PSI could risk damaging hoses or equipment and creating unnecessary complications in maintaining safe operations. Thus, 125 PSI strikes a balance between efficiency and safety in a relay pumping scenario.