Fire Rated Service Transits

Passive Fire Protection, particularly through the use of fire rated service transits, is a fundamental aspect of a building's fire safety strategy. These systems are designed to maintain the integrity of fire compartments by sealing service penetrations, preventing the spread of fire and smoke. The effectiveness of these systems relies on careful design, proper installation, and ongoing maintenance, all of which must be guided by stringent regulatory and testing standards. By understanding and implementing these principles, building professionals can ensure that their structures are well-protected against the dangers of fire.

Definition and Purpose

Passive Fire Protection refers to building components and systems that are integral to the structure itself and are designed to contain or slow the spread of fire and smoke without requiring any active intervention. PFP is crucial for maintaining the integrity of fire compartments, ensuring that fire and smoke are contained within designated areas for a specified period, thereby protecting the structure, enabling safe evacuation, and providing time for firefighting efforts.

Fire Rated Service Transits are a key component of PFP, specifically designed to maintain the fire resistance of walls, floors, and other barriers when services (like cables, pipes, and ducts) penetrate these barriers.

Role of Fire Rated Service Transits in PFP

Functionality:

Fire rated service transits are designed to seal the openings around services that pass through fire-rated walls, floors, and ceilings. These openings, if not properly sealed, can become points of failure in a building’s fire protection strategy, allowing fire and smoke to pass through and compromising the integrity of the fire compartment.

The primary function of these transits is to restore the fire resistance of the barrier by creating a seal that prevents the spread of fire and smoke. This is achieved through the use of materials that can withstand high temperatures and, in many cases, expand or intumesce when exposed to heat, thereby sealing the gaps left by melting or shrinking services.

Components and Materials Used in Fire Rated Service Transits

Intumescent Materials:

Intumescent materials are central to many fire rated service transits. These materials expand when exposed to heat, typically by 5 to 10 times their original volume, filling gaps and creating an insulating char layer that prevents the passage of fire and smoke.

Examples of intumescent products include wraps, sealants, and collars. These are commonly used around pipes (particularly plastic pipes that melt during a fire), cables, and ducts.

Fire-Resistant Foams and Sealants:

Fire-resistant foams are used to fill larger gaps around service penetrations. These foams can expand to fill irregularly shaped openings and provide a robust barrier against fire and smoke.

Fire-resistant sealants are typically used in conjunction with other materials to seal the edges of penetrations, ensuring a tight and fire-resistant closure around services.

Collars and Wraps:

Pipe Collars: These are typically made from intumescent materials and are designed to fit around pipes. In the event of a fire, the collar expands inward, crushing the pipe as it melts and sealing the opening to prevent fire and smoke from passing through.

Wraps: Intumescent wraps are used around cables and pipes where they pass through fire-rated barriers. These wraps expand to fill the void left by the melting or shrinking service, maintaining the fire integrity of the barrier.

Fire-Resistant Mortars:

Used for sealing large openings around service penetrations. These mortars are typically non-combustible and provide a durable seal that maintains the fire resistance of the barrier. They are often used in conjunction with other fire-stopping materials to ensure a comprehensive seal.

Types of Passive Fire Protection Systems Involving Service Transits

Penetration Seals:

Penetration seals are used to firestop the openings around services where they pass through fire-rated walls, floors, or ceilings. These systems can be complex, involving multiple layers of different materials to ensure that the fire resistance of the barrier is maintained.

The choice of sealant or system depends on the type of service, the size of the opening, and the required fire rating. For instance, the materials used to seal around a cable bundle might differ from those used around a plastic pipe.

Fire-Resisting Ductwork and Dampers:

For HVAC systems, where ducts penetrate fire-rated compartments, fire-resisting ductwork and dampers are used. These systems are designed to close automatically in the event of a fire, preventing the spread of fire and smoke through the ductwork.

Fire dampers, for example, are usually installed within the duct and are connected to a fusible link or a fire detection system that triggers the damper to close when a fire is detected. This prevents the fire from travelling through the ducts, which could otherwise compromise multiple fire compartments.

Curtain Wall and Cavity Barriers:

In buildings with curtain walls or cavities, fire rated transits and barriers are essential to prevent the spread of fire within the building envelope. These barriers are often intumescent strips or boards installed at key points to compartmentalise the cavity and prevent fire spread.

These systems are particularly important in modern high-rise buildings, where cavities in the external wall construction could otherwise act as chimneys, rapidly spreading fire between floors.

Design Considerations in Fire Rated Service Transits

Compatibility with Building Elements:

The design and installation of fire rated service transits must consider the construction materials of the building elements they are penetrating. Different substrates (e.g., concrete, gypsum, masonry) interact differently with fire-stopping materials, which can affect the overall fire resistance of the system.

For example, the method of sealing a service penetration in a concrete wall may be different from that used in a drywall partition due to the different thermal and mechanical properties of these materials.

Integration with Other Fire Protection Measures:

Fire rated service transits are just one part of a broader fire protection strategy. They must be integrated with other passive measures (like fire doors and fire-resisting walls) and active systems (such as sprinklers and alarms) to ensure a comprehensive fire safety plan.

This integration often involves coordination between different building systems, ensuring that the fire-rated transits work in harmony with other fire protection elements. For example, a smoke detector might be linked to the activation of fire dampers within ductwork.

Performance Under Real Fire Conditions:

While fire rated service transits are rigorously tested under controlled conditions, their real-world performance can be influenced by various factors, such as the size and type of fire, the configuration of the building, and the nature of the services penetrating the barrier.

Designers and engineers must consider these factors when specifying fire rated transits, ensuring that they are suitable for the specific conditions of the building in question. This might include accounting for potential thermal expansion of services, the possibility of fire spread through concealed spaces, and the impact of building movement during a fire.

Regulatory and Standards Considerations

Building Regulations:

Compliance with building regulations, such as those outlined in Approved Document B in the UK, is essential when designing and installing fire rated service transits. These regulations set out the minimum fire resistance requirements for different types of buildings and services, ensuring that all fire-stopping measures meet the necessary safety standards​​.

These regulations are continually updated in response to lessons learned from real fire incidents, so it is important for designers and contractors to stay informed about the latest requirements and best practices.

Standards and Testing Requirements:

Fire rated service transits must meet stringent testing requirements to be certified for use. Standards such as BS 476 and EN 1366-3 outline the testing procedures for penetration seals, ensuring that they maintain integrity and insulation under fire conditions​​.

These tests simulate the conditions of a real fire, exposing the service transit to high temperatures and measuring its performance over time. The results are used to determine the fire rating of the product, which indicates how long it can be expected to maintain its protective properties in a fire.

Maintenance and Lifecycle Considerations

Ongoing Maintenance:

Fire rated service transits must be maintained throughout the life of the building to ensure they continue to provide effective fire protection. Regular inspections should be conducted to check for any damage or degradation of the fire-stopping materials, especially in buildings where services are frequently modified or upgraded​.

Any repairs or replacements should be carried out by qualified professionals, following the manufacturer’s guidelines and ensuring that the new materials are compatible with the existing fire protection systems.

Lifecycle Cost Considerations:

While fire rated service transits are a critical component of a building’s fire safety strategy, they also represent a significant investment. Building owners and managers must consider the lifecycle costs of these systems, including the costs of installation, maintenance, and any potential replacements over the building’s lifespan​.

By investing in high-quality, certified fire rated transits and maintaining them properly, building owners can reduce the long-term costs associated with fire safety, while also ensuring compliance with regulations and safeguarding the building’s occupants. 

Fire Resistance Criteria

Definitions and Requirements:

Fire Resistance: This is the ability of a building element, like a wall or a floor, to withstand fire exposure for a specified period. This is typically measured in terms of integrity (preventing flames and gases from passing through), insulation (limiting heat transfer), and load bearing capacity (if applicable)​.

Fire Testing and Assessment: Fire rated service transits must undergo rigorous testing to ensure they meet the required fire resistance standards. For example, a fire protective coating for structural steel might be tested for a specific duration to ensure it provides adequate protection during a fire​.

Testing Standards:

BS 476-20: This standard outlines the methods for determining the fire resistance of elements of construction, including service penetrations. Fire rated transits are tested according to this standard to ensure they maintain the required fire resistance when services pass through a fire-rated barrier​.

EN 1366-3: This is a European standard for fire resistance tests on service installations, specifically focusing on penetration seals. It assesses the performance of fire rated transits under fire conditions, ensuring they prevent fire spread through service penetrations​.

Fire Testing and Certification

Testing Processes:

Physical Fire Testing: Before any fire protection system, including service transits, can be marketed, it must undergo physical fire testing. This testing assesses how the system performs under fire conditions, including its ability to maintain the integrity and insulation of the compartment it protects​.

Limitations and Assessments: Not every configuration of a fire rated transit can be physically tested due to practical limitations. Therefore, manufacturers often use assessments or expert judgments to extend the applicability of test results to a broader range of conditions and configurations​.

Certification Levels:

Third-Party Certification: This is the most rigorous form of certification, involving independent evaluation by a certified body like the United Kingdom Accreditation Service (UKAS). This process includes factory production control audits, ongoing product testing, and verification that the products continue to meet fire safety standards​.

Expert Judgement: When full certification isn’t feasible, an assessment by a qualified fire consultant or test laboratory may be used. However, this level of certification does not include the quality control measures inherent in third-party certification​.

Types of Fire Rated Service Transits

Cable Transits:

These systems are designed to seal openings around cables that pass through fire-rated barriers. They often use modular components that can be adjusted or added to as the number of cables increases. These transits must be capable of withstanding fire conditions without allowing fire or smoke to pass through​​.

Pipe Collars and Wraps:

Pipe collars and wraps are specifically designed for plastic pipes, which melt and create openings during a fire. Intumescent collars expand when exposed to heat, sealing off the opening left by the melted pipe, thus preventing fire and smoke from passing through​.

Ductwork and Fire Dampers:

For ducts that penetrate fire compartments, fire dampers are installed to close automatically in the event of a fire. These are crucial in HVAC systems to prevent the spread of fire and smoke through the ductwork. These systems are often tested to ensure they close effectively under fire conditions​​.

Installation and Maintenance

Installation Best Practices:

Compliance with Guidelines: Proper installation according to manufacturer’s guidelines is critical for the effectiveness of fire rated service transits. Incorrect installation can severely compromise the fire resistance of the barrier. Installers must consider the type of service, the material of the barrier, and the specific fire stopping product used​.

Consideration of Substrate: The substrate material, whether it’s concrete, drywall, or another construction material, affects how the fire rated transit should be installed. Different materials may require different fire-stopping solutions to ensure that the fire resistance is maintained​.

Maintenance and Inspections:

Regular Inspections: Regular maintenance is essential to ensure that fire rated service transits remain effective over time, especially in buildings where services might be modified or added after the initial installation​.

Record Keeping: Documentation of the installation and maintenance of fire rated transits is crucial. This includes details of the products used, the installation process, and any inspections or repairs carried out. Keeping accurate records helps in maintaining compliance with fire safety regulations and facilitates future audits​.

Regulatory Compliance

Building Regulations:

Approved Document B: In the UK, fire rated service transits must comply with the fire safety requirements outlined in Approved Document B. This document specifies the fire resistance requirements for various types of buildings and occupancies, ensuring that all fire rated products installed in a building meet the necessary standards​.

Insurance and Legal Implications: Non-compliance with fire safety regulations can have severe consequences, including legal penalties and increased insurance premiums. Additionally, in the event of a fire, non-compliance may result in insurance claims being denied, further emphasising the importance of adherence to regulations​.

Advanced Considerations

Performance-Based Design:

In complex or non-standard buildings, such as high-rise structures or industrial facilities, a performance-based fire safety strategy may be employed. This approach uses scientific and engineering principles to design fire protection systems that meet the specific needs of the building. In such cases, fire rated service transits must be carefully selected and tested to ensure they provide the necessary level of protection​.

Custom Solutions:

For unique or challenging scenarios, standard fire rated transits may not be sufficient. Custom solutions may need to be developed, often in collaboration with fire safety engineers, to address specific risks or requirements of the building. This might involve tailored fire testing and certification processes​​.

Environmental Factors:

Humidity and Chemical Exposure:

The performance of fire rated service transits can be affected by environmental conditions, such as high humidity or exposure to chemicals. In such environments, it may be necessary to use specialised fire-stopping materials that are designed to withstand these conditions without degrading​.

Seismic Considerations:

In seismic zones, fire rated transits must be designed to withstand not only fire but also the structural movements caused by earthquakes. This requires additional testing and certification to ensure that the transits maintain their integrity under such conditions​.

FAQs for Fire Rated Service Transits

What are Fire Rated Service Transits?

Fire Rated Service Transits are specifically designed systems used to maintain the fire resistance of a wall, floor, or other barriers when these are penetrated by building services such as pipes, cables, or ducts. These transits ensure that fire and smoke do not pass through these penetrations, which would otherwise compromise the integrity of the fire compartment.

Why are Fire Rated Service Transits important in building fire safety?

The primary role of Fire Rated Service Transits is to prevent the spread of fire and smoke between different compartments within a building. Compartmentation is a crucial aspect of passive fire protection, as it contains the fire within a defined area for a specified period. This containment allows safe evacuation, protects property, and aids firefighting efforts. Without effective Fire Rated Service Transits, fire and smoke could spread through service penetrations, leading to increased danger to occupants and potential structural damage​​.

How does the building’s fire strategy influence the selection and implementation of Fire Rated Service Transits?

The building's fire strategy plays a crucial role in the selection and implementation of Fire Rated Service Transits. This strategy is a comprehensive plan that outlines how the building will prevent, contain, and respond to a fire. It includes considerations for both passive and active fire protection measures and is designed to ensure the safety of occupants, protect property, and facilitate firefighting efforts.

Fire Compartmentation and Passive Fire Protection

A key element of any fire strategy is fire compartmentation, which involves dividing a building into sections (compartments) to contain the spread of fire and smoke for a specified period. Fire Rated Service Transits are essential components of passive fire protection within these compartments.

• Compartment Walls and Floors: The fire strategy will dictate the required fire resistance rating of compartment walls and floors. When services such as pipes, cables, and ducts pass through these barriers, Fire Rated Service Transits must be selected to match or exceed the fire resistance rating of the compartment. For example, if a wall has a fire resistance rating of 60 minutes, the transit system used must also be rated to maintain that level of fire resistance.
• Penetration Seals: The type and size of services passing through a compartment wall or floor influence the choice of penetration seals. The fire strategy will specify whether additional protection (such as intumescent materials that expand when exposed to heat) is necessary to seal gaps and maintain the integrity of the barrier under fire conditions​​.

Building Use and Occupancy

The fire strategy considers the building’s use and occupancy type, which impacts the selection of Fire Rated Service Transits. Different building uses have varying fire risks and occupant vulnerabilities.

• High-Risk Occupancies: Buildings with high-risk occupancies, such as hospitals, care homes, or industrial facilities with hazardous materials, require more robust fire protection measures. The fire strategy for these buildings will often demand higher fire resistance ratings and more rigorous testing of Fire Rated Service Transits. For instance, in a hospital, where evacuation may be challenging, the fire strategy might require service transits that offer extended fire resistance to ensure that fire and smoke do not compromise escape routes​.
• Complex Building Structures: In large and complex buildings, such as high-rise towers or mixed-use developments, the fire strategy will likely involve a detailed assessment of potential fire spread routes. This includes vertical and horizontal penetrations where services pass through multiple compartments. Fire Rated Service Transits in these buildings must be carefully selected to address the specific challenges posed by complex building layouts, including the potential for fire to spread between different uses or occupancies within the same structure​.

Integration with Active Fire Protection Systems

The fire strategy also considers the interaction between passive and active fire protection systems. In some cases, the selection of Fire Rated Service Transits will be influenced by the presence of active systems, such as sprinklers, fire alarms, and smoke control systems.

• Fire Dampers and Smoke Control: Where ductwork passes through fire compartments, the fire strategy may require the installation of fire dampers that automatically close in response to a fire alarm. These dampers must be compatible with the overall fire strategy and must be selected to work in conjunction with other systems to prevent the spread of fire and smoke.
• Coordination with Detection Systems: In buildings where smoke detectors and alarms are integrated with fire doors or shutters, the fire strategy may specify that certain service transits need to work seamlessly with these systems. For example, a fire-rated cable transit might be required to ensure that power and communication lines for fire detection systems remain operational during a fire, maintaining the functionality of alarms and automatic doors​​.

Regulatory Compliance and Standards

The fire strategy must comply with local building codes and fire safety regulations, which often dictate the minimum standards for fire resistance and the use of Fire Rated Service Transits.

• Building Regulations and Approved Documents: In the UK, for example, Approved Document B of the Building Regulations provides guidance on fire safety and specifies the requirements for compartmentation and fire resistance. The fire strategy will incorporate these regulatory requirements, ensuring that the selected Fire Rated Service Transits are certified and tested according to the relevant British Standards (such as BS 476 or BS EN 13501-2).
• Certification and Testing: The fire strategy will often require that all Fire Rated Service Transits used in the building are third-party certified to ensure they meet the necessary performance criteria. This certification process includes testing for fire resistance, integrity, and insulation, ensuring that the transits will perform as required in the event of a fire​​.

Future-Proofing and Adaptability

Finally, the fire strategy must consider the potential for future changes in building use, occupancy, or service requirements. This adaptability is critical for ensuring that the fire protection measures, including Fire Rated Service Transits, remain effective over the building's lifetime.

• Modular and Scalable Solutions: In buildings where future modifications are likely, the fire strategy may favour modular Fire Rated Service Transits that can be easily adapted to accommodate new services or changes in building layout. These systems must be versatile enough to maintain fire resistance even if the building's use or configuration changes.
• Ongoing Maintenance and Inspection: The fire strategy will outline the need for regular maintenance and inspection of Fire Rated Service Transits to ensure they remain in good condition. This ongoing attention is vital for ensuring that the fire protection strategy remains effective, particularly in buildings where services are frequently updated or modified​​.

The building’s fire strategy is a comprehensive plan that influences every aspect of the selection and implementation of Fire Rated Service Transits. It takes into account the need for compartmentation, the building’s use and occupancy, the integration with active fire protection systems, regulatory compliance, and the need for future adaptability. By aligning the selection of service transits with the overall fire strategy, building owners and managers can ensure that their facilities are well-protected against the risks of fire, providing safety for occupants and resilience for the structure itself.