How is the overall capacity of the relay system determined?

The overall capacity of the relay system is determined by the smallest pump and the smallest diameter of hose used in the relay. This principle is based on the concept of flow restrictions, where the weakest link in the system will limit the total flow capacity.

In a relay operation, multiple pumps and hoses may be employed; however, regardless of the efficiency or capacity of the larger pumps or wider hoses, the flow will ultimately be limited by the smallest components in the system. A smaller pump will have a lower flow rate compared to larger ones, and a hose with a smaller diameter will restrict the volume of water that can pass through it, creating a bottleneck.

Thus, while other factors like pump performance and hose diameter can influence the system, it is the smallest pump and hose that governs the maximum flow capability of the entire relay setup. This is a critical aspect for operations to consider when planning for effective water supply in firefighting scenarios.