Safety Level

Maintaining the reliability and effectiveness of a fire extinguishing system over its operational lifespan is critical, requiring regular inspection and replacement of components affected by aging and corrosion. These procedures ensure the system will function correctly even after long years of readiness.

aging and Corrosion in Fire Extinguishing Systems

 

Fire suppression systems, particularly water-based ones, are highly susceptible to internal corrosion. The primary causes are the presence of oxygen, water, and metal, which lead to various types of corrosion, including pitting corrosion and Microbiologically Influenced Corrosion (MIC). This degradation reduces pipe wall thickness and can lead to system failure or premature leaks.

1. Hose Sets for Special Extinguishing Systems

 

Hose sets, especially those connecting gas extinguishing agent cylinders to the pipe network, are critical components and subject to a natural aging process. Their stability is a basic prerequisite for the system’s functionality.

  • Risk: Over time, the physical properties of the hoses change. Porous hoses can become a serious risk, potentially leading to the hose bursting upon activation, resulting in system failure and danger to personnel.

  • Action: Hoses and their fittings must be checked during routine inspections. Standards (like DIN 20066) often limit the duration of use (including storage time) to six years, after which they must be replaced. Increased loads or environmental influences may require earlier replacement.

2. Reliability Verification of Fire Detection Systems

 

The fire detection system is the “eyes and ears” of the suppression system. Its reliability depends on the consistent performance of its components over time, which can be affected by dirt, environmental changes, and component degradation.

  • Key Checks: Verification involves a multifaceted approach:

    • Sensitivity Testing: Smoke detectors require sensitivity testing (often every two years) to ensure they respond accurately without false alarms.

    • Component Integrity: Visual inspection for damage, wear, or paint on detectors, control panels, and wiring.

    • Battery Checks: Inspection and testing of backup batteries to check for corrosion and ensure they can supply power during an outage.

    • Functional Tests: Triggering manual pull stations, heat sensors, and smoke detectors to confirm the entire alarm and notification chain works as intended.

3. Surveying of Compressed Air Tanks

 

Compressed air tanks are often used in dry pipe or pre-action sprinkler systems, as well as for storing clean agents. These pressure vessels require special attention due to the high-pressure environment.

  • Risk: The metal of the tank is subject to stress and corrosion, especially if moisture is present in the compressed air. This can compromise the vessel’s structural integrity.

  • Action: Cylinders containing compressed gas must be subject to periodic hydrostatic testing and internal examination. High-pressure cylinders typically require testing at intervals not exceeding 10 years (and often before the 20-year mark, and every 10 years thereafter) to confirm the tank is structurally sound and can withstand the required pressure. Flexible connections on these systems must also be regularly inspected and replaced.

4. Inspection of Old Water Extinguishing Systems

 

Older water-based systems (like wet pipe and dry pipe sprinklers) are highly prone to internal pipe corrosion and organic deposits (encrustations).

  • Dry Pipe Systems: These have a higher risk of corrosion because trapped water at low points (where the oxygen-rich compressed air is present) accelerates corrosion. Inspections are often required more frequently (e.g., every 12.5 years under some guidelines).

  • Wet Pipe Systems: Corrosion is less severe but still occurs, usually at air pockets in the system’s high points. Inspections are typically required every 25 years under some guidelines.

  • Action: The inspection process involves:

    • Endoscopic Examination: Video scoping the pipe network to check for corrosion, pitting, and deposits.

    • Sample Analysis: Taking random pipe and sprinkler samples for laboratory analysis to determine residual wall thickness and the severity of metal loss.

    • Corrective Measures: Intensive flushing, replacement of corroded pipes, and substitution of defective sprinkler heads are implemented if the system fails the inspection criteria.

Regular, scheduled maintenance and testing are the cornerstones of ensuring a fire extinguishing system remains a reliable safety asset, effectively combating the twin threats of aging and corrosion to sustain its operational readiness.