Can you run a fire pump without water?

Fire pumps are critical components of fire protection systems, ensuring reliable water supply during emergencies. But what happens if a fire pump runs without water? Many facility managers, engineers, and fire safety professionals have asked this question while installing, testing, or maintaining their systems.

In this article, we will explain why running a fire pump without water (dry running) is highly dangerous, what damage it can cause, how NFPA 20 and other standards regulate fire pump operation, and the best practices to avoid costly system failures.

1. Why Fire Pumps Should Never Run Without Water

A fire pump is designed to move water, not air. When the impeller inside the pump rotates without water, it cannot create the hydraulic pressure needed for proper operation. Instead, the pump experiences dry running, which leads to several problems:

• Friction and Overheating – Water normally lubricates the pump’s internal components. Without it, friction rises rapidly, leading to high temperatures that damage seals, bearings, and impellers.

• Cavitation Damage – Running without water causes air bubbles inside the pump casing. When these bubbles collapse, they create shockwaves that erode internal surfaces.

• Motor or Engine Overload – Whether you’re using an electric fire pump or a diesel-driven unit, running dry forces the driver to work harder, risking burnout or engine seizure.

In short, operating a fire pump without water can lead to catastrophic pump failure within minutes.

2. The Role of NFPA 20 in Fire Pump Operation

The National Fire Protection Association (NFPA) 20 standard defines the installation and operation guidelines for fire pumps. According to NFPA 20:

• Fire pumps must be primed before starting.

• Running pumps without water supply is prohibited except under controlled testing conditions.

• Automatic shutdown systems should be installed to prevent dry running during failures in water supply.

By following NFPA 20, facilities can minimize risks and ensure compliance with international fire safety codes.

3. Scenarios Where Dry Running May Occur

Even if you follow best practices, there are situations where a fire pump might unintentionally operate without water:

a) Water Supply Failure

If the water tank, reservoir, or city main feeding the pump is empty or blocked, the pump may continue running without realizing there’s no water.

b) Improper Priming During Commissioning

During system startup, technicians sometimes forget to prime the pump, leading to immediate dry running damage.

c) Valve Misalignment

If suction valves are closed or partially obstructed, water cannot reach the impeller, causing the pump to run dry.

d) Testing Mistakes

During routine fire pump testing, failure to connect the test header properly or open the necessary valves can result in dry operation.

Recognizing these risks early is essential to prevent pump damage and downtime.

4. The Consequences of Running a Fire Pump Without Water

Dry running a fire pump can cause significant mechanical and safety issues, including:

• Seal Failure – The mechanical seals that keep water inside the pump rely on water for cooling. Without it, seals burn out rapidly.

• Impeller Wear – Impellers overheat, warp, or crack when operated dry, requiring costly replacements.

• Casing Damage – Cavitation can cause pitting and erosion on the pump casing surface.

• Motor Burnout – Electric fire pumps may draw excessive current, leading to motor winding failure.

• Diesel Engine Overload – Diesel-driven pumps risk overheating and piston damage if operated dry.

• Reduced System Reliability – A damaged pump may fail to operate during an actual fire emergency, endangering lives and property.

A single dry running incident can cost thousands of dollars in repairs and replacements. Prevention is far more cost-effective.

5. How to Prevent Dry Running in Fire Pumps

As a fire pump manufacturer, we recommend several preventive measures to protect your system:

a) Install Low-Pressure Sensors

Integrate sensors on the suction side to detect when water levels are too low, automatically stopping the pump before damage occurs.

b) Perform Routine Maintenance

Check suction valves, strainers, and pipelines regularly to ensure unobstructed water flow.

c) Follow NFPA 25 for Testing

NFPA 25 recommends proper wet testing procedures to ensure that water is available before starting the pump.

d) Verify Priming Before Startup

Always confirm that the pump casing is filled with water before running tests or performing initial startups.

e) Use Automatic Control Panels

Modern fire pump controllers can be configured to detect dry running conditions and shut the system down automatically.

These preventive steps safeguard both your pump investment and your overall fire protection system.

6. Testing Fire Pumps Without Water: Is It Ever Safe?

In certain cases, fire pump manufacturers and service teams may perform “no-flow tests” or dry testing—but these are done under controlled conditions:

• The pump is run for only a few seconds.

• Low-speed modes are used to avoid overheating.

• Specialized monitoring equipment ensures safe operation.

Unless you are a certified fire pump technician, never attempt to test a pump without water on your own. Doing so can void warranties and compromise system safety.

7. How to Troubleshoot a Fire Pump That Has Run Dry

If your fire pump has accidentally run without water, act immediately:

1. Shut Down the Pump – Stop operation to prevent further damage.

2. Inspect Seals and Bearings – Check for signs of overheating or leakage.

3. Check the Impeller and Casing – Look for cracks, erosion, or warping.

4. Examine Motor or Engine Health – Measure winding resistance for electric motors and temperature levels for diesel engines.

5. Contact the Manufacturer – A qualified fire pump manufacturer or service provider should inspect the unit and recommend repair or replacement.

Timely intervention can reduce repair costs and prevent complete system failure.

8. Why Choosing a Reliable Fire Pump Manufacturer Matters

Selecting a trusted fire pump manufacturer ensures that your system includes built-in safeguards against dry running. At Better Technology Group, we design and manufacture UL-listed and NFPA 20-compliant fire pumps with features like:

• High-quality mechanical seals resistant to heat damage

• Smart controllers that monitor water levels

• Durable impellers designed for heavy-duty operation

• Expert technical support for troubleshooting and maintenance

Choosing the right manufacturer means better protection, higher reliability, and lower long-term costs.

9. Key Takeaways

• Running a fire pump without water is dangerous and can cause severe damage within minutes.

• NFPA 20 prohibits dry running and provides guidelines for safe operation.

• Prevent dry running by installing sensors, performing regular maintenance, and ensuring proper priming.

• Always consult your fire pump manufacturer for testing and troubleshooting procedures.

• Investing in high-quality, NFPA-compliant pumps protects both property and lives.
  

Conclusion

Fire pumps are vital for protecting people, property, and assets during emergencies. Running them without water—even briefly—can lead to severe equipment damage, costly repairs, and system failure during critical moments. By understanding the risks, following NFPA guidelines, and working with a reliable manufacturer, you can ensure your fire protection system operates safely and effectively when it matters most.