How to design mechanical fire protection system coordination and integration

 

Fire protection insights

• The article applies fire and life safety foundational knowledge to some notable mechanical equipment-specific issues relevant to health care buildings.
• In addition, fire protection engineers can take a deeper look at some coordination and integration challenges specific to atrium smoke control.

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The coordination and integration of modern fire protection, life safety and mechanical systems require a common understanding of these systems’ performance objectives to ensure effective and successful planning, design, construction, inspection, testing, maintenance and operation. Rich examples where many fire protection and life safety system types require careful integration include fire pump rooms and fire command centers. Beyond these, there are many other technical nuances to fire protection and life safety system types.

For instance, there are three active fire protection system classifications: fire protection, fire suppression and fire extinguishing. There are many more passive fire protection systems. A detailed understanding of these system types is necessary for every team.

This article stresses that a common understanding of fire protection and life safety systems’ performance objectives will help better orient mechanical, fire protection and life safety system (MFPLS) designers to successfully address health care coordination and integration challenges, especially in the case study the article considers — a life safety atrium smoke control system. Note: A future article will discuss the integration of electrical, fire alarm, smoke control and life safety systems.

What are fire protection systems?

Fire protection systems typically encompass specific mechanical design elements, such as sprinkler systems, standpipe systems and fire pumps. But to exclusively hone in on sprinklers, is to bely the full scope and nature of the fire protection discipline. For example, the fire protection pump room in Figure 1 includes nine active and passive fire protection system elements with coordination issues involving architectural, structural, civil, mechanical, electrical and plumbing scopes of work.

Six active fire protection systems include:

• A site underground fire service main system.

• A fire and jockey pump system.

• Multiple automatic wet pipe fire sprinkler systems.

• Multiple automatic dry pipe fire sprinkler systems.

• Multiple single interlock preaction systems.

• Associated drainage systems.

Note: There is no standpipe system in the rendered image.

Separately, three distinct passive fire protection system elements include a mechanical incidental use fire separation, a stairwell vertical opening fire separation and a fire pump room fire separation. As a discipline, fire protection engineering strategically approaches internal and external fire safety challenges for the built environment. Fire protection engineering does this by integratingall key stakeholders to achieve performance objectives for a specific hazard.

In the case of a fire pump room, numerous critical elements are needed to mitigate active and passive fire protection system hazards. Active fire protection systems may be life safety systems depending on the system’s role and function (see definition below). Similarly, passive fire protection systems may also be life safety systems working together with active systems to protect people. Active and passive fire protection concepts are crucial to an ordered understanding of fire and life safety. They are defined by the NFPA Glossary of Terms, 2021 Edition, as follows:

Active fire protection system: A system that uses moving mechanical or electrical parts to achieve a fire protection goal (for definition, see NFPA 3: Standard for Commissioning of Fire Protection and Life Safety Systems, 2018 Edition Article 3.3.20.1). Active fire protection systems must move mechanically or be initiated to move by an electrical means. These active fire protection system elements include fire sprinklers, valves and pumps.

Passive fire protection system: Any component of a building or structure that provides protection from fire or smoke without any type of system activation or movement (for a definition, see NFPA 3 Article 3.3.20.5). Passive fire protection systems rely upon the compartmentalization spaces within the built environment to control the spread of fire or smoke.

Passive fire protection systems include:

• Fire or smoke assembly type.

• Associated opening protectives.

• Penetrations protection.

• Joints sealant.

• Thermal and sound insulation.

• Fire-resistance features.

When requiring a rated passive fire protection system, some opening protectives may also include active and life safety system elements such as:

• Fire, smoke, combination, ceiling radiation and corridor dampers.

• Balanced, low-energy power-operated, power-assisted, power-operated, exit access, fire exit.

• Glazing for fire door and window assemblies.

• Smoke guards and adjustable door floor sweeps.

In addition to clarifying the roles of active and passive fire protection systems, it is vital to understand the three main goals active systems aim to achieve as they relate to mechanical systems: fire protection, fire suppression and fire extinguishing.

Fire protection: Methods of providing for fire control or fire extinguishment (for a definition, see NFPA 801: Standard for Fire Protection for Facilities Handling Radioactive Materials, 2020 Edition Article 3.3.13). Fire protection systems are designed for normal hazard classifications and intended to control fire size by covering the fire, limiting its heat production and wetting adjacent combustibles to prevent structural damage.

Fire suppression: Sharply reducing the heat release rate of a fire and preventing its regrowth by means of direct and sufficient application of water through the fire plume to the burning fuel surface (for a definition, see NFPA 13: Standard for the Installation of Sprinkler Systems, 2019 Edition Article 3.3.76). Suppression systems are engineered for a specific hazard and listed based on full-scale fire testing. Fire suppression systems forcefully knock down the fire while breaking up the fuel source and limiting its consequential effects.

Fire extinguishing: The complete suppression of a fire until there are no burning combustibles (see NFPA 750: Standard on Water Mist Fire Protection Systems, 2019 Edition Article 3.3.8). Extinguishing systems are engineered for a specific hazard and listed based on full-scale fire testing. Extinguishing systems quench burning by cooling the fire, smothering the air supply, removing the fuel source or interrupting the chemical reaction.

The overarching goal of all active and passive fire protection systems is to protect people and property. When an active or passive system has historically protected people and property against near misses, injury, loss events, mission continuity, environmental protection or preservation of cultural resources, it is a sign that the system is achieving its goal. The surest sign an active or passive system must reconsider how it has been designed is if the building envelope encounters something called “flashover”:

“When the upper layer temperature reaches approximately 1,100°F, pyrolysis gases from the combustible contents ignite along with the bottom of the ceiling layer … those present in the room are unlikely to survive.”

Evaluation of active or passive systems that have failed to achieve their performance objectives are reevaluated by code authorities and codes and standards development committees and addressed in the code development process. In addition to the fire prevention efforts of active and passive fire protection systems, life safety systems also play a critical role in ensuring the life safety of occupants, first responders, neighbors and nearby communities.

What are life safety systems?

Life safety systems typically encompass specific mechanical design elements, such as elevator systems, emergency generators, fire alarm systems, smoke control and dampers. Like the discussion of fire protection systems, this is a siloed view of life safety systems. There are also nonmechanical life safety systems, such as means of egress and emergency lighting. As noted previously, active and passive fire protection systems may also be life safety systems depending on their goal and function. Life safety systems are defined in the NFPA Glossary of Terms, 2021 Edition, as:

Life safety systems: Those systems that enhance or facilitate evacuation, smoke control, compartmentalization and isolation (for a definition, see NFPA 4: Standard for Integrated Fire Protection and Life Safety System Testing Article 3.25.6).

A fire command center is a rich example of a life safety system. Fire command centers require more than 18 critical life safety elements to ensure a facilitated emergency response. These fire command centers employ active and passive life safety system elements.

A more specific example of a mechanical life safety system is where initiation controls actuate a combination fire/smoke damper. Integrating either fire pump rooms or fire command centers requires significant coordination between MFPLS stakeholders.

Specifying mechanical engineers focus on heating, ventilation, air conditioning (HVAC) and/or thermal and fluid system applications. In contrast, specifying fire protection engineers focus on active smoke control systems, explosion protection and prevention systems, passive building systems, egress systems and human behavior to design the building envelope for fire events. In health care, mechanical system equipment components may trigger active or passive fire and/or life safety system requirements (see Table 1).

Table 1 : Resulting equipment-specific system requirements Mechanical system Fire protection system Life safety system Active or passive Actuators x x Both Air distribution x x Both Boilers and furnaces x x Both Compressors – x Both Condensers/evaporators – x Passive Connections x x Both Control system components x x Both Control valves x x Both Controls x x Both Cooling tower x x Both Cooling/heating coils x x Both Energy recovery – – – Fluid coolers – x Active Fluid distribution/piping x x Both Heat exchanger – x Passive Pressure vessels – x Both Pumps and fans x x Both Pumps/compressors/fans x x Both Refrigerants x x Both Refrigeration components – x Both

Table 1: In health care, mechanical system equipment components may trigger active or passive fire and/or life safety system requirements, based on the code. Courtesy: WSP USA

MFPLS coordination, integration in health care

Air distribution system are among health care’s most prevalent mechanical systems. For a typical air distribution system, NFPA 90A: The Standard for the Installation of Air-Conditioning and Ventilating Systems, 2021 Edition, Chapter 5 helps to clarify specific passive MFPLS integration challenges. Chapter 6 details controls requirements for active MFPLS components.

For a more unique atrium smoke extraction system, NFPA 92: The Standard for Smoke Control Systems, 2021 Edition, Chapter 6, clarifies passive and active MFPLS integration challenges. Note: Both standards impact nondedicated systems.

Implementing these safe practices is further complicated for the mechanical systems in defend-in-place health care facilities, as articulated in NFPA 99: The Health Care Facilities Code, 2021 Edition, Chapter 16, and NFPA 101: Life Safety Code, Chapters 18 and 19.

Passive fire protection systems must be inspected or tested per NFPA 3 Article 5.4.1.2 and active fire protection systems must be inspected and tested in accordance with NFPA 4 per NFPA 3 Article 5.4.1.3. These considerations are evaluated in the following case study of a three-story atrium smoke extraction system.

[subhead/h2] Case study of atrium smoke extraction

With any fire protection and life safety system, beginning with the end in mind is recommended. For this reason, the framework of this case study is based on a confidential client’s real-life atrium smoke control system example. System coordination and integration efforts will follow NFPA 3. The framework of this standard illustrates benchmark activities to be conducted for commissioning fire protection and life safety systems in the planning, design, construction and occupancy phases.

The fire protection and life safety planning phase has three primary purposes:

• To detail the owner’s project requirements (OPR) with the relevant stakeholder team.

• The formation of the commissioning team.

• The development of the commissioning plan.

At the minimum, the commissioning team should include the owner and the fire commissioning agent. An ideal team would consist of a testing and balancing professional, a registered mechanical engineer and a registered fire protection engineer. The commissioning team or a third-party entity approved by the local authority may perform special smoke control inspections.

Atrium smoke extraction integration challenges that the commissioning team should consider in the planning phase of a project include the following:

• Applicable and conflicting codes, standards, guides and technical references such as ASHRAE, ICC, NFPA, SFPE.

• Specific user requirements: Building management, remote testing, emergency lighting

• Training requirements: Fire protection engineering, mechanical engineering and testing and balancing training for smoke control. Other training modules, such as enclosures, energy code issues and emergency management, should also be considered.

• Warranty requirements:

  • Active systems: Firefighter’s smoke control station, exhaust system components, supply system components, door components, fire and smoke dampers, fire alarm initiation devices, access control devices, fire alarm notification devices, fire sprinkler system zoning.

  • Passive systems: Building enclosure façade system, fire shutters, fire and smoke doors, air barriers, stairwells.

• Integrated testing requirements: All active and passive fire protection systems require integrated testing in new structures if two or more fire protection or life safety systems are integrated. Following system acceptance, periodic testing is also required, as indicated in the test plan, but no less than every 10 years.

• Performance criteria: Acceptance tests for an atrium exhaust system include requirements for detection devices, ducts, inlets and outlets, fans, smoke barriers and controls.

• Third-party requirements: Smoke control system testing shall be by approved agencies for smoke control testing with expertise in fire protection engineering, mechanical engineering and certification as air balancers.

Fire protection system design phase

The fire protection and life safety design phase follows the same three precepts as the planning phase as informed by the OPR:

• Development of the basis of design (BOD).

• Guidance and input are to be taken from the commissioning team.

• The commissioning plan will be updated accordingly with particular attention to scope and design issues.

The rational analysis report is the other important smoke control document for consideration in the design phase. Design effect considerations for successful MFPLS coordination and integration of active and passive systems include:

Passive fire protection and mechanical system design coordination and integration: Fire sprinkler system: MFPLS coordination of fire protection sprinkler systems may be influenced by a phenomenon known as stratification in spaces with high ceilings and glass glazing. Depending on how a mechanical engineer designs the HVAC system or informs architects of building envelope energy performance issues, solar radiation may cause hot air to become more buoyant than a smoke plume in a fire event, prohibiting sprinklers’ activation. Note: Fire detection systems are also influenced by stratification.

Passive fire alarm and mechanical system design coordination and integration: Fire alarm emergency voice and communications system (EVACS): MFPLS coordination of acoustical systems is one mechanical area that often impacts an EVACS design. Frequently, atrium spaces are subject to acoustically distinguishable space (ADS) requirements. The voice fire alarm system in an ADS is required to be intelligible. Mechanical HVAC and acoustical engineers must coordinate noise, reverberation and echoes, which may impact the fire alarm system’s design intelligibility.

Active fire protection and mechanical system design coordination and integration: Fire sprinkler system: MFPLS integration of fire protection sprinkler systems requires that the sprinkler system be zoned with the atrium space to ensure that if a sprinkler activates, the system’s interconnected water flow alarm will know to trip the atrium smoke control system. Note: Fire alarm systems may also be influenced by atrium detection, initiation and notification system zoning requirements.

Active fire alarm and mechanical system design coordination and integration: Fire initiation and detection system: MFPLS coordination of detection and initiation systems within the built environment may impact fire system detection capabilities. Ducted and indoor air quality designs may influence ducted air velocity, air humidity, air temperature and the system’s final exhaust flow rate may influence smoke color and density. Depending on indoor air quality design provisions, design specification of thermodynamics, psychometrics, heat transfer, fluid mechanics, energy and mass balance and heating and cooling loads may affect fire system detection capabilities.

Active smoke control and mechanical systems design coordination and integration: HVAC: MFPLS integration of HVAC systems is vital to a functional smoke control system

• Makeup air is sized based on exterior openings, interior forced air, leakage into the atrium building envelope or other mechanical system sources. Note: Makeup air must be limited below the exhaust air condition to ensure the atrium environment remains negatively pressurized.

• Exhaust air is sized based on natural ventilation from the space or mechanical means. The steps in this sizing are the specification of a design fire and the evaluation of visibility, velocity, temperature and asphyxiant tenability thresholds.

• Exhaust air inlets incorrectly located may cause plughole effects.

• Exhaust system temperatures will influence damper fire rating requirements.

• Extraction fans associated louvers, door controls and dampers are controlled by a dedicated firefighter’s smoke control station.

• Fire and smoke damper systems are typically required at smoke control shaft and smoke compartment boundaries duct openings. The damper closing influences the speed at which makeup air may be injected into an atrium space.

• The building automation system provides additional monitoring of the system.

• The graphics annunciator panel is observable from a fire command center.

• The smoke extraction system must integrate with testing elements for other smoke control systems.

• The smoke extraction system must integrate with testing elements for other HVAC systems.

• Additional considerations for HVAC systems include structural fire ratings of system support, exhaust air conditioning temperature, facade penetration requirements and fire-rated housing for variable frequency drives.

The above provisions must be coordinated in the planning and design phases.

Integrating fire, life safety and mechanical systems

Successful system integration requires a holistic understanding of the place and purpose of MFPLS systems within health care buildings. Fire protection systems are divided into active and passive system types. Fire protection, fire suppression and fire extinguishing systems are all mechanical systems specifically focused on addressing fire hazards by protecting people and property. Life safety systems also serve other building system concepts to amplify their goal of preserving life.

This case study illustrates a smoke control system design’s fire, life safety and mechanical integration elements. Integrating the fire, life safety and mechanical systems, especially smoke control systems is challenging but achievable with the right skills, perspectives and objectives working together as a team.

A future article will further evaluate this case study from the perspective of integration of electrical, fire alarm, smoke control and life safety systems.

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