Published on November 30, 2025
Your fire pump system operates under significant pressure, and without proper protection, that pressure can become dangerous. Pressure relief valves (PRVs) are critical safety components that protect your system from overpressure conditions that could cause catastrophic failure, pipe bursts, and equipment damage. Yet many building owners and facility managers don't fully understand how PRVs work, when they need maintenance, or the difference between overhaul and replacement.
At Apex Pumps, we've seen systems compromised by failed or improperly maintained PRVs that went undetected until testing revealed problems. Understanding PRV technology, recognizing maintenance needs, and knowing when to overhaul vs replace is essential for maintaining system safety and AS1851 compliance.
This comprehensive guide covers everything you need to know about fire pump pressure relief valves—from how they protect your system to CLA-VAL PRV maintenance, overhaul kits, circulation relief valves, and AS1851 compliance requirements.
What Are Pressure Relief Valves and Why Are They Essential?
A pressure relief valve (PRV) is a critical safety component that protects your fire pump system from overpressure conditions. When system pressure exceeds a safe limit, the PRV automatically opens to release excess pressure, preventing damage to pipes, fittings, pumps, and other system components.
Without a functioning PRV, your fire pump system has no protection against overpressure. This can lead to catastrophic failures including pipe bursts, equipment damage, system shutdown, and serious safety risks. PRVs are not optional—they're mandatory safety components required for AS1851 compliance.
Key functions of pressure relief valves:
- Overpressure Protection: Automatically opens when system pressure exceeds safe limits
- System Safety: Prevents catastrophic failure and equipment damage
- Pressure Regulation: Maintains system pressure within safe operating ranges
- Compliance: Required for AS1851 compliance and insurance coverage
- Equipment Protection: Protects pumps, pipes, and fittings from excessive pressure
PRVs are typically installed on the discharge side of fire pumps and are set to open at a pressure slightly above the system's normal working pressure but below the maximum pressure rating of system components.
Understanding CLA-VAL PRV Technology
CLA-VAL is a leading manufacturer of pressure relief valves for fire protection systems. Their pilot-operated PRVs are widely used in Australian fire pump installations and are known for reliability and precision.
CLA-VAL PRVs use a pilot-operated design where a small pilot valve controls the main valve. This provides:
- Precise Pressure Control: Accurate pressure setting and response
- Reliable Operation: Consistent performance under varying conditions
- Quick Response: Fast opening when overpressure occurs
- Durability: Designed for long service life in fire protection applications
Apex Pumps stocks CLA-VAL PRVs in threaded configurations, available in 25mm and 50mm sizes. These valves are designed to protect your system from overpressure while maintaining system integrity and compliance.
Overhaul Kits vs Full Replacement: Making the Right Decision
When your PRV needs attention, you have two options: overhaul with a replacement kit or full valve replacement. Understanding when each is appropriate helps you make cost-effective decisions.
When Overhaul Is Appropriate
PRV overhaul involves replacing the internal components (typically the diaphragm) while keeping the valve body. Overhaul is suitable when:
- Valve body is in good condition with no corrosion or damage
- Only internal components (diaphragm, seals) need replacement
- Valve is relatively new or well-maintained
- Overhaul kits are available for your valve model
- Cost of overhaul is significantly less than replacement
Apex Pumps stocks CLA-VAL overhaul kits for 25mm and 50mm W Series valves. These kits include the diaphragm and necessary components to restore valve performance.
When Replacement Is Necessary
Full valve replacement is required when:
- Valve body shows corrosion, damage, or wear
- Valve is incompatible with current system requirements
- Overhaul parts are no longer available
- Repeated overhaul failures indicate valve is beyond repair
- System upgrades require different valve specifications
- Valve is very old and replacement is more cost-effective
During routine maintenance, our technicians assess PRV condition and provide recommendations for overhaul or replacement based on valve condition, cost-effectiveness, and system requirements.
Circulation Relief Valves: Protecting Pumps from Overheating
Circulation relief valves serve a different but equally important function. While PRVs protect against overpressure, circulation relief valves protect pumps from overheating during low-flow conditions.
When fire pumps operate at very low flow rates or against closed valves, the pump can overheat due to recirculation of water within the pump casing. Circulation relief valves maintain minimum flow by opening when flow drops below a set point, allowing water to recirculate and preventing pump damage.
Key functions of circulation relief valves:
- Minimum Flow Protection: Ensures adequate flow to prevent pump overheating
- Pump Protection: Prevents damage from low-flow operation
- System Efficiency: Maintains pump efficiency during low-demand periods
- Hydraulically Controlled: Responds directly to flow conditions without pilot operation
Apex Pumps stocks 25mm CLA-VAL W Series circulation relief valves. These hydraulically controlled valves are non-pilot operated and provide reliable minimum flow protection for fire pump systems.
Both PRVs and circulation relief valves are essential safety components. Understanding their different functions helps you maintain a complete, compliant fire protection system.
Signs Your PRV Needs Attention
Recognizing early warning signs can prevent system failure and ensure compliance. Watch for these indicators:
- Leaking: PRV leaking or dripping when system is at normal pressure
- Failure to Open: PRV doesn't open when pressure exceeds set point during testing
- Premature Opening: PRV opens at pressures below the set point
- Diaphragm Failure: Visible damage, corrosion, or deterioration of diaphragm
- Corrosion: Valve body or components showing significant corrosion
- Incorrect Pressure Setting: PRV set point doesn't match system requirements
- Failed Testing: PRV fails AS1851 testing or calibration verification
If you notice any of these signs, schedule immediate inspection and testing. Early detection prevents system failure and ensures AS1851 compliance. Apex Pumps can assess your PRV during routine testing and provide recommendations for overhaul or replacement.
Choosing the Right PRV Size: 25mm vs 50mm
Selecting the correct PRV size is critical for effective overpressure protection. The size depends on your system's flow capacity and pressure relief requirements.
25mm Pressure Relief Valves
25mm PRVs are suitable for:
- Smaller fire pump systems
- Lower flow rate applications
- Systems with limited space requirements
- Standard commercial fire pump installations
Apex Pumps stocks 25mm CLA-VAL pilot-operated pressure relief valves with threaded connections, as well as 25mm overhaul kits for W Series valves.
50mm Pressure Relief Valves
50mm PRVs are required for:
- Larger fire pump systems
- Higher flow rate applications
- Systems requiring greater relief capacity
- Industrial or high-capacity fire pump installations
Apex Pumps stocks 50mm CLA-VAL pilot-operated pressure relief valves with threaded connections, as well as 50mm overhaul kits for W Series valves.
If you're unsure about the correct size, our technicians can assess your system during routine maintenance and recommend the appropriate PRV size based on pump capacity, system flow rates, and pressure requirements.
AS1851 Compliance and Testing Requirements
Pressure relief valves and circulation relief valves are critical safety components under AS1851 and must be regularly tested and maintained. The testing schedule includes:
- Monthly: Visual inspection
- Six-monthly: Operation and pressure setting verification
- Annually: Full performance testing
- Five-yearly: Comprehensive service and overhaul
During routine testing, our technicians verify PRV pressure settings, test operation, check for leaks, and assess overall condition. All testing is documented, and recommendations are provided for overhaul or replacement if valves fall outside acceptable tolerances or show signs of failure.
Why Choose Apex Pumps for PRV Services?
At Apex Pumps, we understand that pressure relief valves and circulation relief valves are critical safety components. Our team has extensive experience with CLA-VAL PRVs, overhaul procedures, and replacement installations.
Our clients choose us for:
- Expert Assessment: Accurate evaluation of PRV condition and recommendations for overhaul vs replacement
- Quality Parts: Genuine CLA-VAL PRVs, overhaul kits, and circulation relief valves in stock
- AS1851 Compliance: Complete testing and documentation for compliance requirements
- Transparent Pricing: Clear quotes for overhaul or replacement with no hidden costs
- Quick Response: Fast turnaround for PRV assessment, overhaul, or replacement
Whether you need PRV testing, overhaul, or replacement, Apex Pumps provides expert service backed by quality parts and comprehensive documentation. We stock CLA-VAL PRVs, overhaul kits, and circulation relief valves to keep your system operational and compliant.
Final Thoughts
Pressure relief valves and circulation relief valves are not optional components—they're essential safety systems that protect your fire pump installation from overpressure and pump damage. Understanding PRV technology, recognizing maintenance needs, and knowing when to overhaul vs replace ensures your system remains safe, compliant, and reliable.
If your PRV needs testing, overhaul, or replacement, or if you're unsure about your system's safety components, contact the Apex Pumps team today. We'll assess your valves, provide expert recommendations, and ensure your system meets AS1851 compliance requirements.