Integrating Fire Alarm Systems
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Fire alarm systems are commonly used to supervise, monitor, and control functions of other building systems. They integrate with other fire protection and building systems in almost every project. Therefore, thoughtful consideration is needed to properly address the detailed hardware and software issues for integrating fire systems with other building systems. Such practice is not only “good design,” it will make installation and maintenance easier, too. This article provides a recipe of high-level and detailed information to consider on your next integration project.
The term integration has a variety of meanings. To some, integration consists of the monitoring or control of other building equipment, systems, or subsystems by a protected premises fire alarm system. To others, integration means the use of a common communications infrastructure that serves multiple systems in a building.
The interface between a fire alarm system and another building system can be code-mandated, such as that for activation of a smoke control system, the supervision of control valves serving fire sprinkler systems, and elevator recall. Integration also can be optional and voluntary. An example of voluntary integration is a combination system where the BAS and the fire alarm system are integrated and share a common infrastructure using a network protocol such as a BACnet or LonWorks. Such integration can include HVAC systems management, lighting systems, security systems, door locks, fire alarms, and more. The application of a common infrastructure on which these systems can operate has allowed integration of systems that historically have required independent network communications. A common infrastructure for communications can provide cost savings, or allow for redundancy and robustness at a reasonable cost.
Systems and functions that are commonly interfaced with fire alarm include:
Automatic sprinkler systems and other extinguishing systems
Elevator recall and power interruption
Control of air distribution systems—HVAC fan and damper controls
Door release and door unlocking
Mass notification systems
Fire extinguisher monitoring.
Some of these functions are considered “fire safety functions” within the context of NFPA 72: National Fire Alarm Code and are intended to increase the level of life safety for occupants or to control the spread of fire’s harmful effects. Other systems or functions may be integrated for other reasons, including cost savings, information sharing, and operational benefits.
Implications and considerations
The best time to begin planning for integration is early in the design process. Evaluating the implications of integration early in a project will help to determine if such an approach is practical and desirable. Reducing costs, sharing information, consolidating equipment, and consolidating information to a single workstation are good reasons for integrating systems. As noted earlier, redundancy in communication and system robustness also can be implemented in a cost-effective manner through shared communication infrastructure.
Integration has several practical implications, many of which are particular to local conditions involving the owner, contractor, and inspectors, including:
System operation and acceptance: Can the installer get the system operating and accepted by the authority having jurisdiction in time for a certificate of occupancy? If delays occur due to system operation and acceptance problems, how will they impact the project?
Ongoing O&M: If part of the integrated system goes down, can the remaining parts of the system still operate? Will the life safety system portion of the integrated system remain functional if other aspects of the system have trouble or fail? Will the system be reliable?
Contractual concerns related to the possibility of separate installers and no single point of responsibility.
Fire alarm reliability
As integration relates to fire alarm systems, NFPA 72 has specific provisions for combination systems and for fire safety functions that are performed by the fire alarm system. A core premise of integration as allowed by NFPA 72 is that fire alarm systems have a high level of reliability. Therefore, the functions of the fire alarm system must take precedence over other building systems in the integrated environment.
NFPA 72 addresses reliability concerns for combination systems with specific requirements. These requirements include provisions for listed barrier gateways when a fire alarm signaling line circuit is shared with another system. Transport equipment (servers and routers) must be listed for fire alarm service (except under specific conditions) when they are located in a fire alarm signaling path.
For fire safety functions, a basic requirement of NFPA 72 is that control of fire safety functions not interfere with other operations of the fire alarm system such as fire detection, notification of building occupants, notification of emergency responders, and supervision of fire suppression systems. To help prevent such interference, one provision in NFPA 72 requires that relays used for control functions must be listed and work within the voltage and current limitations of the fire alarm control unit. Compliance with the requirements of NFPA 72 and NFPA 70: National Electrical Code will limit the possibility of adverse interference with the fire alarm system operation.
Adequate coordination and compliance with the provisions of NFPA 72 and NFPA 70 will help ensure that proper integration is achieved and that the end product is reliable. Coordination among the combined systems and disciplines will help limit ambiguities in the specified approach and implementation. The goal is to achieve properly integrated systems that function as intended and avoid interferences that can result in system reliability and performance issues.
NFPA 72 does not limit the types of systems that can be combined with fire alarm systems. However, functions of the fire alarm system are to take priority over non-fire alarm functions and systems. The one exception to this rule is that mass notification may take precedence over the fire alarm system. This exception recognizes that communication to building occupants in an emergency situation such as a terrorist attack may need to take priority over the fire alarm system.
Integration is not always a straightforward process. Coordination and a good understanding of the integration approach are essential to achieving a properly operating system. A lack of proper planning during the design phase can lead to ambiguous objectives as well as complications during the installation phase of a project. Coordination is vital for multiple project participants including the design professionals (mechanical, electrical, fire protection engineers, etc.) and the installing contractors (fire alarm contractor, mechanical contractor, electrical contractor, etc.).
Integration can be achieved via multiple approaches. Defining the approach and systems integration architecture is a key step in the planning and coordination process. The design team communicates the integration approach typically within the project specifications. The specifications should contain equipment descriptions, performance criteria, and operational descriptions that are accurate and clear.
Three important steps in the overall integration process are:
Coordination among the design professionals that results in documentation of a clear plan for integration.
Development and implementation of a commissioning/testing plan that will include adequate testing to verify proper operation of the combined systems after they are installed.
Preparation of quality O&M manual documents to describe the key components of the systems and how the systems should be operated and maintained. A quality O&M manual will allow the end user to have the systems properly serviced and functioning over time.
When deciding on the integration approach, many factors should be considered. Some of the most important include:
Will the sequence of installation and operation of the integrated components affect the granting of a certificate of occupancy? An authority may grant a temporary certificate of occupancy if the HVAC system isn’t completed, but if the system is fully integrated and the fire alarm system isn’t operational at the time occupancy is needed, it would be difficult to obtain even a temporary certificate of occupancy.
Will the configuration allow for ease of maintenance and testing? If part of the system is offline, does the entire system need to be offline?
Does the ongoing operation of the fire /life safety system require multiple vendors or a single vendor? If multiple vendors are needed, troubleshooting issues become very complex and difficult to manage.
Potential integration snafus
One of the more complex integration challenges is the integration of fire alarm systems with smoke control systems. Smoke control systems that use dedicated stand-alone equipment, such as for stair pressurization or the normal building HVAC, may be used to provide smoke control. The HVAC may be supplemented by dedicated equipment. Often, numerous smoke control dampers are required to modulate to different positions depending on the area of fire origin.
With these types of systems, it is critical to develop a detailed matrix of operation that includes all of the dampers and fans that are required to operate (or turn off) and the positions they are required to be in for normal and emergency operation for each given fire/smoke scenario. The operation of these devices can be controlled by the BAS that receives input form the fire alarm system, or the fire alarm system can be designed to override and control the equipment. In either event, the detailed matrix of operation becomes the road map for the design, installation, and ongoing testing and maintenance of the system.
Fire safety functions
When complete integration with other building systems is not planned for a project, a fire alarm system often will still interface with other independent building systems to perform fire safety functions. The relay or appliance that activates fire safety functions must operate within the voltage and current limitations of the fire alarm control unit and must be listed and suitable for the intended purpose.
In addition to these general requirements, NFPA 72 contains specific requirements for protected premises fire safety functions related to elevator recall for firefighters service, elevator shutdown, HVAC systems, door release, door unlocking devices, and exit marking audible notification systems. The 2010 edition of NFPA 72 (which will be put before the membership of NFPA at its annual meeting in June 2009) relocates the criteria for fire alarm system operation of fire safety functions to a separate chapter to facilitate the use of the code.
Read more about NFPA 72-2010 here.
Operational testing can ensure that interfaced and integrated systems function properly. Functional testing at the time of system acceptance in combination with inspection and testing at regular intervals thereafter, in accordance with NFPA 72, will verify that the fire alarm system and fire safety functions are working properly. A system cause-and-effect matrix is a good resource to verify that system inputs are initiating performance of the appropriate outputs and that the system is operating in the approved manner. NFPA 72 requires tests of fire safety functions that consist of operating or simulating alarm signals. Testing personnel must be qualified and experienced in the arrangement and operation of interface equipment and fire safety functions. In an integrated system, technicians for other systems also may be needed for testing.
Fire alarm systems integrate with other fire protection and building systems in almost every project. Giving thoughtful consideration to designing the integration will ease the installation and ongoing maintenance of the systems.
|Mahoney is an Associate with Arup in Washington, D.C., where he focuses on fire protection engineering.|
Interface of elevator systems with fire alarm systems
Fire safety functions for elevators are related to removing elevators from normal service by recalling them to a primary or alternate floor where emergency responders can access and use them. Elevator shutdown is another fire safety function. When the application of water from sprinklers could cause unsafe elevator operations, ASME A17.1: Safety Code for Elevators and Escalators requires that a means be provided to automatically disconnect the main line power supply from the affected elevators upon or prior to the application of water, due to concerns of shorting electrical equipment and water getting on the braking system for the elevator.
The method for initiating main line power disconnect is generally accomplished in one of two ways by the fire alarm system: (1) via a water flow detection device that serves the sprinklers in the elevator machine room or elevator shaft, or (2) heat detection devices located adjacent to the fire sprinklers in the elevator machine room or elevator shaft. Both approaches are permitted by ASME A17.1. However, certain jurisdictions require that a specific method be used for shutdown. For example, for U.S. Dept. of Defense facilities, Unified Facilities Criteria document 3-600-01: Fire Protection Engineering for Facilities requires that water flow detection be used to remove power to the elevators.
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