The inlet where the fire department pumps water into a building's sprinkler or standpipe system — what an FDC is, how to recognize the connection types, and how to supply one on the fireground.
A fire department connection (FDC) is the inlet on the outside of a building where an engine pumps water to back up the building's built-in fire protection — its sprinkler system, its standpipe, or both. The building's own supply is designed to get things started; the FDC is how the fire department adds the pressure and volume to finish the job. Supplying it correctly is one of the highest-impact things a pump operator does at a commercial or high-rise fire.
Sprinkler and standpipe systems are fed by a municipal supply that is sized to hold a fire, not always to overwhelm it — and in a tall building, gravity works against every gallon. Pumping into the FDC boosts pressure and flow into the system so sprinkler heads keep flowing and hose crews on upper floors get usable pressure at the outlet. On many systems, especially high-rise standpipes, the FDC is not a backup at all — it is the primary way the system reaches working pressure.
The placard matters because the two systems ask for different pressures:
For a standpipe, the FDC pump pressure has to overcome three things stacked together:
FDC Pressure = System Demand + Friction Loss + Elevation
When a required pressure is placarded on the FDC, use it. When it is not, the pre-incident plan is your best source — this is exactly the number a good pre-plan should hand you instead of making you solve it under stress.
What is a fire department connection? An FDC is an inlet on the outside of a building where the fire department pumps water to boost the building's sprinkler system, standpipe, or both — adding the pressure and volume the built-in supply cannot provide on its own.
How much pressure do you pump into an FDC? It depends on the system. A sprinkler FDC is often started around 150 psi, while a standpipe FDC must overcome the outlet demand (about 100 psi on a modern system) plus friction loss plus roughly 5 psi per floor of elevation — so a high-rise needs considerably more. Use the placarded pressure or the pre-incident plan when available.
What is the difference between a sprinkler and standpipe FDC? A sprinkler FDC supports automatic sprinkler heads; a standpipe FDC supplies hose outlets that crews connect to on the floors above. The identification plate on the FDC tells you which system it serves.
Should you assume a sprinkler or standpipe system is already charged? No. A closed valve, an impaired system, or a broken main can leave the system dry, so the FDC may be the only water reaching the fire. Supply it promptly whenever ordered.
Get the supply math right before the tones drop: build your discharge pressure with the free Pump Discharge Pressure Calculator, work the losses in your supply and attack lines with the Friction Loss Calculator, and confirm the hydrant behind you can carry the load with a fire hydrant flow test.