Jockey Pump
The Pressure Maintainer

The Problem It Solves

A sprinkler system is never perfectly leak-free. Air bleeds out of fittings, a waterflow switch may weep, a small crack in a gauge adapter slowly drops pressure. Without anything to push back, system pressure slowly falls — and eventually the fire pump starts, runs for thirty seconds, pressurizes the system, and shuts off. Then the leak drops pressure again. On it goes: start, stop, start, stop.

That churning is bad for the fire pump's bearings, seal assembly, and controller contactors. NFPA 20 solves it with a much smaller pump that runs whenever pressure drops even slightly, replenishes the leak, and shuts off before the main pump ever sees a demand.

Sizing and Setpoints

NFPA 20 Annex A.4.26 gives sizing as a rule of thumb: flow no greater than the system's allowable leakage rate (typically 1–10 gpm) at a discharge pressure about 10 psi above the fire pump churn pressure. Setpoints follow the so-called 10-psi rule:

This stacking ensures the jockey always picks up before the fire pump does. If the jockey fails or cannot keep up with a real demand, pressure drops further and the fire pump starts.

Jockey Pump vs. Fire Pump

ITM Notes

NFPA 25 does not require a separate test program for the jockey pump — it's tested passively during every fire pump weekly churn and annual flow test. But you should still observe:

• Jockey pump stops cleanly when pressure is restored.
• Cycling is infrequent (more than a few starts per hour means an unaddressed leak or an undersized jockey).
• Jockey never runs continuously (that indicates it cannot meet the leak rate — a real problem).

References