Evolution 10 — Sprinkler System Supply (FDC)

Overview

When a building's sprinkler system activates, the fire department augments the system's water supply through the FDC. This evolution teaches operators to supply the correct pressure and flow to a sprinkler system without over-pressurising the piping. Unlike standpipe operations where you are supplying hose lines, sprinkler systems have fixed piping with specific pressure ratings. Over-pressurising a sprinkler system can burst pipes, flood uninvolved areas, and compromise the system's ability to control the fire. The operator must deliver enough pressure to keep the activated sprinkler heads flowing effectively while respecting the system's design limits. Two supply lines to the Siamese connection must be balanced to prevent turbulence and uneven flow distribution.

Training Objective

Supply a building sprinkler system via the FDC using two balanced supply lines at the correct system pressure. Maintain pressure within the system's design parameters without over-pressurisation.

Skills Practiced

• Sprinkler system FDC procedures and connection
• Dual-line balanced supply to Siamese connection
• System pressure requirements for different sprinkler types
• Siamese connection operations and flow balancing
• Avoiding over-pressurisation of fixed piping systems
• Understanding the difference between standpipe and sprinkler FDC requirements
• Monitoring for system pressure feedback

Setup

Hydrant supply with two discharge lines connected to the building's Siamese FDC. Both lines must flow at equal rates to properly supply the sprinkler system. The target FDC pressure is typically 150 PSI but varies by system design and local requirements.

Scenario

A commercial building with an activated sprinkler system. Multiple sprinkler heads have opened on the fire floor. The building's domestic water supply is supplementing the system, but the fire department must augment through the FDC to ensure adequate pressure and flow reach all activated heads. The pump operator connects to the FDC and brings the system to operating pressure.

What to Expect

The simulation monitors pressure at the FDC and flow balance between the two supply lines. Unbalanced lines (more than 15% flow difference) or excessive pressure (above system rating) will result in scoring penalties. The operator must bring pressure up gradually — a sudden pressure spike can damage sprinkler piping.

Tips

• Both lines to the Siamese should flow at the same rate — open them simultaneously and balance
• Know the required FDC pressure for sprinkler systems in your jurisdiction — typically 150 PSI
• Over-pressurising a sprinkler system can cause pipe failure and flood uninvolved areas
• Open both lines gradually and balance them before increasing throttle to target pressure
• Sprinkler FDC pressure is usually lower than standpipe FDC pressure — do not use standpipe numbers
• If you see water flowing back out of the FDC, the check valve may be failed — notify command