Jockey Pump
A jockey pump is a small pressure-maintenance pump on the fire main that automatically compensates for minor leakage, holding the system at set pressure so the main fire pump starts only when real firefighting demand drops the line.
Why it matters on an MEPF project
Every charged piping network seeps slightly. Without a jockey pump, the main fire pump would short-cycle on every small pressure sag — brutal on the machine and masking the difference between seepage and a genuinely open hydrant. The pressure-switch cascade is the design point: jockey cuts in first on a small drop; a larger, faster drop starts the main pump.
The jockey is also the system's built-in leak detector: its start frequency, logged over a week, tells you the health of the whole network. A jockey that runs every few minutes is reporting a leak or a passing valve — attention paid there is a repair; attention withheld is a failed inspection or worse.
How it's specified in practice
| Parameter | Typical / working position | Governing reference |
|---|---|---|
| Jockey cut-in | Small pressure sag (seepage scale) | scheme design per NBC 2016 Part 4 |
| Main pump start | Larger/faster drop (an outlet opened) | scheme design |
| Jockey capacity | A small fraction of main pump flow — enough for seepage, never for firefighting | standard practice |
| Health indicator | Start frequency log = network leak-tightness | maintenance practice |
Common mistakes
- Oversizing the jockey until it can mask a genuinely open outlet.
- Setting cut-in/cut-out so close to main-pump start that both race.
- Ignoring rising jockey start frequency — the free leak alarm nobody reads.
- Wiring the jockey through a switched circuit that gets turned off at night.
Related on this site
One of 68 working definitions in the MEPF & solar engineering glossary. The buying side of the same decisions is in the buyer's guides; the numbers are in the calculators.
Frequently asked
My jockey pump runs every ten minutes — is that normal?
No. Frequent cycling means the network is losing pressure — a leak, a weeping valve, or a passing check valve. Log the frequency, find the loss, fix it; the jockey is telling you something the inspection would also find.
Can the jockey pump fight a fire?
No — it is deliberately far too small. Its only job is holding static pressure. Firefighting flow is the main (or standby) pump's job, triggered automatically when pressure drops beyond the jockey's ability to hold.
Standards referenced: NBC 2016 Part 4 (scheme context)