Enclosure Integrity Testing for Gaseous Fire Suppression Systems in Combustion Turbines
Enclosure integrity is essential for gaseous fire suppression systems inside combustion turbine enclosures. Compromised enclosure integrity can lead to gas leakage, reducing the gas concentration and undermining fire suppression effectiveness. This Quick Tip summarizes key considerations and NFPA requirements to help verify that combustion turbine enclosures are properly sealed and capable of maintaining the design concentration. Applicable guidance can be found in NFPA 12 for CO₂ systems and NFPA 2001 for Clean Agent systems.
Why Enclosure Integrity Matters
Gaseous fire suppression systems for combustion turbines rely on maintaining a minimum concentration for a specified time to effectively suppress a fire. Missing, failed or poor sealing of an enclosure can compromise system performance, an issue made more likely from the complex penetrations and seams typical in combustion turbine enclosures.
Systems must be designed and installed to achieve and maintain the required concentration throughout the protected space. Enclosures must be tight enough to limit leakage and prevent loss of agent during discharge and hold time.
Initial Testing of a Newly Installed System
Before a CO₂ system is placed into service, an acceptance concentration test must be performed to verify that the system can achieve and maintain the required concentration inside the combustion turbine enclosure to extinguish a fire. This test confirms that the system has been installed correctly, the enclosure is adequately sealed, and the system will function as designed.
Clean Agent fire suppression systems do not require concentration testing. However, they do require that the enclosure be examined and tested to locate and effectively seal any significant air leaks that could result in a failure to hold the specified agent concentration for the required holding period. This can be accomplished by using an approved blower fan unit or by other approved means that achieves quantifiable and recorded results to demonstrate effectiveness.
For CO₂ systems, a blower fan unit test should ideally be performed in conjunction with the initial concentration testing. Subsequent blower fan tests can then confirm the enclosure remains in the same condition as when it originally passed a concentration test.
Common Sources of Leakage in Combustion Turbine Enclosures
Combustion turbine enclosures present unique challenges. Common leakage points include:
- Cable and conduit penetrations
- Pipe and tubing penetrations
- HVAC openings and louvers
- Access doors, hatches, and panels
- Floor, wall and ceiling joints
Recommended Testing Frequencies
AEGIS recommends annual, documented visual enclosure integrity inspections for all enclosures protected by gaseous suppression agents.
While subsequent blower fan testing is not mandated by NFPA for Clean Agent systems, AEGIS advises that it be conducted every five years or at the conclusion of an outage where the enclosure has been disassembled, for both CO₂- and Clean Agent-protected enclosures.
A full discharge concentration test should be performed whenever a CO₂-protected enclosure has been significantly modified or when maintenance indicates it is advisable. For high-pressure CO₂ systems, consider aligning full-discharge testing with cylinder hydrostatic testing to minimize costs and system impairments.
AEGIS recommends a phased approach to minimize costs and disruption: start with light and/or smoke testing to identify and correct leaks, then confirm performance with a blower-fan test or a full-discharge test.
Recommended Inspection Practices
- Seal any new openings created during maintenance or equipment upgrades. Re-check these areas after major outages.
- High temperature areas can degrade gasket materials. Replace any that are cracked, missing, or permanently compressed.
- Ensure and document that all automatic dampers function correctly, manual dampers are in their proper positions, and ventilation fan shutdown interlocks operate as intended.
Tips to Improve System Reliability
- Keep a record of each visual enclosure integrity inspection
- Keep an updated penetrations log for the enclosure
- Train maintenance teams on the importance of resealing after work
- Verify doors operate properly after outages
- Include enclosure integrity inspection in pre-outage and post-outage checklists
- Coordinate with OEMs before modifying combustion turbine enclosures or ventilation paths
Please call your AEGIS Property Loss Control Professional with any questions regarding enclosure integrity testing.
