As manufacturers and suppliers of fire and life safety equipment, we recognize our role extends beyond product creation. We are dedicated contributors to the safety, well-being, and sustainable development of the communities we serve. In this context, fire-resistant ductwork, often referred to as “fire-rated ducting,” stands as a critical component of passive fire protection, essential for high-rise buildings, metros, shopping malls, hospitals, and underground car parks.
The Crucial Role of Fire-Rated Ductwork
Why are fire safety products vital in buildings? The answer is twofold: to protect lives—both occupants and firefighters—and to safeguard property by maintaining building integrity, limiting collateral damage, and preserving building functions.
Fire-rated ducts play a pivotal role in fire protection as a key part of the passive fire protection system. Their primary function is to contain fire and prevent its spread from one compartment to another. This containment provides crucial time for occupants to evacuate in breathable air conditions and allows firefighters to effectively perform their duties. Furthermore, it supports active fire protection systems like sprinklers, enabling them to suppress the fire more efficiently. Rapid fire spread can overwhelm even the most robust active systems.
Types and Testing Standards
Fire-rated ducts are available in coated and non-coated steel. The critical factor is that any system, regardless of its type, must be rigorously tested and certified to meet stringent criteria. Testing and certification must adhere to the time-temperature curve, rather than being limited to specific temperatures like 400°C or 600°C.
The time-temperature curve (Figure 1), defined by standards like ISO 834, represents the heat progression in a furnace during fire testing. For example, at 60 minutes, the temperature reaches approximately 925°C, and at 2 hours, it reaches 1049°C. Standards like BS476-24 and EN1366- 8, 9 follow this curve for fire-rated duct testing. Therefore, full-temperature curve testing is essential for a product to be recognized as fire-rated.
Applications and Performance Criteria
Fire-rated ducts are indispensable in critical applications such as mechanical ventilation, smoke extraction, staircase pressurization, make-up air ducts, and kitchen extract ducts. These applications require fire-rated ductwork to prevent secondary fires and ensure breathable air during evacuation, even when ducts traverse multiple fire zones.
The potential risks of flashovers, uncontrollable secondary fires, and loss of life and property far outweigh the marginal cost increase associated with insulated ducts. Every investment in fire safety yields a substantial return in safeguarding lives and property.
Performance criteria for fire-rated ductwork, as defined by BS and EN standards, include stability, integrity, insulation, cross-section, and kitchen duct specific requirements. Tests must be conducted under two scenarios: fire outside the duct (Duct A) and fire inside and outside the duct (Duct B).
- Stability: Ducts must remain intact and stable across supports, without collapsing.
- Integrity: No fire or flame leakage should occur inside or outside the ducts, including wall penetration seals.
- Insulation: Surface temperatures of duct insulation must remain below 140°C on average and 180°C at any specific point above ambient temperature.
- Cross-Section: For smoke extraction, 75% of the cross-section must be maintained during testing.
- Kitchen Duct: The duct must withstand external fire while maintaining internal temperatures below 140°C on average and 180°C at any specific point.
Key Considerations for Specifiers
When evaluating fire-rated ductwork, consultants should ask critical questions:
- Is the duct tested to the full time-temperature curve?
- Are all criteria met for both Duct A and Duct B?
- Are integrity, stability, and insulation ratings adequate?
- Are Test Certificates verified? (Test Certificate must be issued by accredited certifying body)
- For Smoke and kitchen extract, has the duct been tested with insulation as a system?
- For smoke extract, is the smoke extraction criteria mentioned in the test certificate.
In line with our unwavering commitment to providing the highest level of fire safety, we are proud to introduce the innovative Airmaster Fire-Rated Ductwork System. This system not only surpasses international Fire & Life Safety Code standards but also achieves exceptional fire ratings, rigorously tested and certified by APPLUS Laboratories (Spain) and holding approvals from Dubai and Abu Dhabi Civil Defense. The system is fully compliant with testing standards BS476-24, “Fire tests on building materials and structures – Part 24: Method for determination of the fire resistance of ventilation ducts.” Offering superior fire ratings of up to 120 minutes for stability, integrity, and insulation (Duct Type A & B), enhanced smoke extraction meeting stringent cross-section criteria, and backed by globally recognized accreditations, this system provides ultimate safety for smoke control systems, effectively restricting flashover and secondary fires. The system is aligned with evolving regulations, emphasizing eco-friendliness and ease of installation. At Airmaster, we ensure the highest quality passive fire protection for your projects, reinforcing our dedication to building a safer and more secure environment for all.
For more information: Airmaster Fire Safety Equipments, Bangalore, Email: Sales.blr@airmaster.co.in
