Engineering Guidelines for Selecting Jockey Pump Flow and Pressure in Fire Protection Systems

In a fire pump system, the jockey pump (pressure maintenance pump) ensures stable system pressure and prevents unnecessary starting of the main fire pump. Correct jockey pump sizing is essential for system reliability and compliance with NFPA 20.

Below are the established engineering recommendations for selecting jockey pump flow and pressure:

1. Jockey Pump Flow: Approximately 1% of the Fire Pump Rated Flow

A widely accepted engineering guideline is:

Jockey Pump Flow ≈ 1% of Fire Pump Capacity

Example:

• Fire Pump Capacity: 1000 GPM

• Jockey Pump Flow: 1% × 1000 GPM = 10 GPM

This compensates for normal system pressure loss caused by minor leaks, thermal contraction, or valve seepage—without being large enough to satisfy real fire demand.

2. Jockey Pump Pressure: +10 PSI or +10–20 PSI Depending on Application

NFPA 20 does not specify an exact pressure requirement; however, engineering practice has formed two commonly used rules:

A. Standard Recommendation: +10 PSI

Jockey Pump Pressure = Fire Pump Rated Pressure + 10 PSI

This is suitable for:
✔ Low-rise commercial buildings
✔ Small to mid-size sprinkler systems
✔ Stable, low-pressure fire protection networks
✔ Projects with minimal static pressure fluctuation

This “+10 PSI rule” is widely referenced in pump manuals, design guides, and UL/FM installation documentation.

B. Engineering Recommendation for Complex Systems: +10–20 PSI

Jockey Pump Pressure = Fire Pump Pressure + 10 to 20 PSI

This range is used in more demanding applications, where a fixed +10 PSI may be insufficient.

Applicable scenarios include:
✔ High-rise buildings with large static pressure variation
✔ High-pressure or multi-zone fire protection networks
✔ Industrial systems (oil & gas, power plants, manufacturing)
✔ Long-distance pipe networks with greater pressure loss
✔ Systems experiencing water hammer or nighttime pressure drops
✔ Projects requiring tighter control of fire pump start-up logic

The additional pressure margin ensures:

• Stable pressure maintenance

• Prevention of nuisance fire pump starts

• Reliable operation in dynamic hydraulic environments

3. Why Proper Jockey Pump Selection Matters

Correct jockey pump settings ensure system reliability by:

• Maintaining stable network pressure

• Preventing unnecessary fire pump activation

• Reducing wear on fire pumps, drivers, and controllers

• Ensuring NFPA 20–compliant pressure sequencing

• Enhancing overall fire protection system performance

Improper selection may cause false starts, pressure instability, or even failure of the fire pump to activate correctly during an actual fire.

4. NMFIRE Support

NMFIRE offers complete technical assistance for selecting jockey pumps matched to our UL/FM certified fire pump systems. From low-rise commercial buildings to high-pressure industrial facilities, our engineering team helps ensure optimal pressure control and full compliance with international standards.