Fire protection systems follow a different engineering logic from everyday water systems.
In most building services, energy efficiency and operating cost are major priorities. In a fire pump system, the first priority is readiness:
Will the system provide the required water when it is needed?
This does not mean that the main fire pump should start every time system pressure changes. Minor leakage, temperature variations, testing, or small pressure losses can occur without an actual fire demand.
This is why many fire protection systems use a smaller pressure-maintenance pump—commonly known as a jockey pump—before the main fire pump.
What Is a Jockey Pump?
A jockey pump is a small pump used to maintain pressure in a water-based fire protection system.
Its purpose is to compensate for minor pressure losses caused by conditions such as:
- Small leakage
- Valve seepage
- Temperature-related pressure changes
- Minor system testing
- Pressure loss over time
The jockey pump restores normal system pressure without unnecessarily starting the main fire pump.
It is not designed to supply the required fire flow.
Why Is the Main Fire Pump Not Used for Every Pressure Loss?
A main fire pump is designed to provide a substantial flow rate and pressure during fire demand.
Starting it for every minor pressure change could cause:
- Unnecessary motor or engine starts
- Additional mechanical stress
- Battery or fuel-system loading
- Increased maintenance
- Pressure surges
- Unnecessary alarm activity
- Difficulty distinguishing minor leakage from genuine demand
Using a smaller jockey pump separates ordinary pressure maintenance from emergency fire pump operation.
How Does the Starting Sequence Work?
A typical pressure-based sequence may operate as follows:
- System pressure falls slightly.
- The jockey pump reaches its start setpoint.
- It starts and attempts to restore pressure.
- If the demand is small, pressure recovers and the jockey pump stops at its defined setpoint.
- If demand is greater than the jockey pump can supply, pressure continues to fall.
- The main fire pump reaches its lower start setpoint and starts.
- The main pump provides the required fire protection flow and pressure.
The exact sequence, settings, and stopping logic must follow the approved system design and applicable requirements.
Does the Jockey Pump Always Start First During a Fire?
Not necessarily in a clearly observable sequence.
If a sprinkler, hydrant, or hose connection creates a large and rapid demand, system pressure may pass through the jockey pump’s start point and quickly reach the main fire pump’s start setting.
The jockey pump may receive a start signal first because of its higher pressure setting, but it cannot satisfy genuine fire flow. The main fire pump then starts as pressure continues to fall.
The important principle is that small pressure losses are handled without unnecessary main pump operation, while significant demand activates the fire pump.
Why Are the Pressure Setpoints Different?
The jockey pump’s start pressure is generally set higher than the main fire pump’s start pressure.
This creates a pressure sequence:
- Normal system pressure
- Jockey pump start
- Main fire pump start
- Additional fire pump start levels where required by the approved design
Setpoints must be separated sufficiently to avoid overlap, unstable operation, or accidental starts caused by normal fluctuations.
They should not be selected from a universal rule of thumb without considering:
- Static water-supply pressure
- Required system pressure
- Pump curves
- Building height
- Controller characteristics
- Pressure-sensing arrangement
- Applicable standards
- Approved fire protection calculations
Can the Jockey Pump Extinguish a Fire?
No.
A jockey pump is not intended to deliver the system’s required fire flow. Its capacity is deliberately limited to pressure maintenance.
If it is large enough to satisfy a meaningful sprinkler or hose demand, it could delay the pressure drop required to start the main fire pump.
The jockey pump must therefore be selected as part of the complete fire protection design—not as a smaller substitute for the fire pump.
What Is the Main Fire Pump’s Role?
The main fire pump supplies the required flow and pressure when the available water source cannot meet the fire protection demand on its own.
It may support systems such as:
- Automatic sprinklers
- Standpipes
- Hydrants
- Hose systems
- Foam-water systems
- Other approved water-based fire protection installations
Its required performance is determined by hydraulic calculations, water-supply conditions, and the applicable design criteria.
How Does the System Detect Fire Demand?
The fire pump normally responds to a hydraulic condition rather than directly detecting flames or smoke.
When water is discharged through the fire protection system, pressure falls. A dedicated sensing arrangement communicates this pressure change to the fire pump controller.
The controller then starts the driver according to the approved logic.
Fire detection and alarm systems may communicate with the broader building infrastructure, but the fire pump starting arrangement must follow the requirements of the approved fire protection design.
Why Is Pressure Maintenance Important Even Without a Fire?
Keeping the system pressurised helps ensure that:
- Water is already available throughout the network
- Small leaks do not repeatedly start the main pump
- Abnormal pressure loss can be identified
- The system remains ready for immediate demand
- Pressure conditions can be monitored over time
A fire protection system does not wait until an emergency to become pressurised. Readiness is maintained continuously.
Is Every Small Pump in a Fire Pump Room a Jockey Pump?
No.
Pump rooms may contain equipment serving different functions, including:
- Jockey pump
- Main electric fire pump
- Diesel-driven fire pump
- Additional fire pump
- Drainage or sump pump
- Test or transfer equipment
A pump’s function must be confirmed from the approved drawings, controller, nameplate, and system documentation.
Does Every Fire Pump System Require the Same Arrangement?
No.
The required number of pumps, driver types, water supplies, controllers, and pressure settings depends on:
- Applicable code or standard
- Adopted edition
- Project location
- Building risk
- Hydraulic calculations
- Water-supply reliability
- Authority requirements
- Insurer or civil defence requirements
NFPA 20 addresses stationary fire pump installations, including general requirements, electric and diesel drives, controllers, and acceptance testing. The project-specific arrangement must be approved under the applicable framework.
Why Must Fire Pump Starting Be Reliable?
A fire pump may remain on standby for long periods and still be expected to start immediately when required.
Readiness depends on:
- Reliable controller operation
- Available electrical power or fuel
- Suitable batteries for diesel starting
- Correct pressure sensing
- Open valves
- Adequate water supply
- Periodic inspection and testing
- Proper maintenance
- Suitable pump-room conditions
The starting sequence is only as reliable as the complete system supporting it.
Why Are Periodic Tests Necessary?
Testing helps verify that:
- Pressure switches and sensors respond
- Jockey pump settings are correct
- The fire pump starts as intended
- Controllers function
- Power or fuel is available
- Alarms are transmitted
- The pump develops expected pressure
- Abnormal noise, vibration, or leakage is identified
The procedures and frequencies must follow the adopted standard, approved maintenance programme, manufacturer instructions, and authority requirements.
What Happens If the Jockey Pump Runs Frequently?
Frequent jockey pump operation may indicate:
- System leakage
- A leaking non-return valve
- Incorrect pressure settings
- A failed pressure tank where used
- Pressure-sensing problems
- Temperature-related changes
- A deteriorating pipe or valve condition
Repeated operation should be investigated rather than accepted as normal.
Future Fire Protection Systems Will Provide Greater Visibility
Digital monitoring can give operators more information about:
- System pressure
- Jockey pump cycles
- Fire pump status
- Controller alarms
- Power availability
- Battery condition
- Room temperature
- Test history
- Abnormal pressure loss
This information can support readiness, but it cannot replace approved controllers, physical inspections, periodic testing, or maintenance.
Conclusion
The main fire pump is not intended to respond to every small pressure loss.
The jockey pump normally manages minor pressure changes and keeps the system ready without unnecessarily starting the main unit. When a genuine fire demand exceeds the jockey pump’s limited capacity, pressure continues to fall and the main fire pump starts.
This sequence reflects a central principle of fire protection engineering:
The system should avoid unnecessary operation during normal conditions while remaining ready to deliver full performance during an emergency.
Frequently Asked Questions
Why does the jockey pump start before the fire pump?
Its start pressure is typically set higher so that it can correct minor system pressure losses before the main fire pump is required.
Can a jockey pump supply sprinkler demand?
It is not intended to supply the required fire flow. Genuine sprinkler demand should cause pressure to continue falling and activate the main fire pump.
What happens if the jockey pump is oversized?
It may satisfy more flow than intended and potentially delay the pressure reduction that starts the main fire pump.
Why does the jockey pump start repeatedly?
Possible causes include leakage, faulty valves, unsuitable setpoints, sensing problems, or other pressure losses in the system.
Does the fire alarm directly start the fire pump?
Fire pumps commonly start in response to a pressure drop through their approved sensing and controller arrangement. Exact logic depends on the approved system design.
Does every fire pump system need a jockey pump?
The pressure-maintenance arrangement depends on the applicable standard and approved design. Requirements should be confirmed for each project.