What is the minimum size of FDC piping that requires two inlets according to regulations?

The minimum size of Fire Department Connection (FDC) piping that requires two inlets is 4 inches according to regulations. This requirement is established to ensure adequate water supply and flow capacity for firefighting operations.

When the FDC piping is 4 inches or larger, the demand for water during a fire incident increases significantly. Two inlets help to improve the flow rate and maintain adequate pressure in the system, which is crucial for effective firefighting. This design consideration helps to accommodate larger volume requirements and allows for simultaneous connections to multiple firefighting apparatus, thereby enhancing the system's overall performance.

In contrast, sizes smaller than 4 inches typically do not necessitate dual inlets because the flow and pressure capabilities are generally sufficient with a single inlet. Therefore, regulations stipulate that the larger pipe sizes, starting from 4 inches and above, must incorporate the dual inlet design for improved efficiency and safety.