Fire Alarms for the Future
CSE: Have you noted any significant changes in how fire-alarm systems are set up in buildings since the events of 9/11? HEIN: Many people are beginning to recognize the importance of fire-alarm systems as part of a comprehensive security system. We've also seen a keen interest in emergency-evacuation systems.
CSE: Have you noted any significant changes in how fire-alarm systems are set up in buildings since the events of 9/11?
HEIN: Many people are beginning to recognize the importance of fire-alarm systems as part of a comprehensive security system. We've also seen a keen interest in emergency-evacuation systems. Since the fire system supervises all audio system functions, its place in the mind of security personnel has become paramount.
Another trend since 9/11 is the increased use of CCTV equipment. Obviously, having a camera pan-tilt-and-zoom based on a specific fire detector input provides a visual indication of the location, and could give responders insight into what to expect.
CLARK: The most significant changes we've noted are those related to survivability. More often than not, we find requirements for redundant circuits, especially in voice-evacuation systems for high-rise buildings. There is also increased demand for better intelligibility or clarity in voice-messaging systems.
HEIN: Fortunately, there's been a lot of technological advances facilitating these changes. For example, audio signals can now be transmitted digitally throughout the building, but converted back to an analog signal close to the speakers. This eliminates electrical noise typical of lighting ballasts and other high-voltage circuits. It also permits multiple messages—up to eight—that can be sent over a single pair of wires.
This also allows unique voice messages to be broadcast simultaneously providing area-specific instructions based on the initiating event.
Of course, there's also been a lot of human factor interface improvements including large multi-line LCD displays, color graphic maps and closed-circuit television pictures based on alarm-specific information.
CSE: On the subject of communications, many fire devices are now intelligent and therefore have the capacity to interface with other building systems. Has the need for more comprehensive control systems pushed greater levels of system integration?
SHORT: Since 9/11, the integration of security and fire-alarm systems is becoming more common, as well as the connection of fire-alarm systems to the building automation system. It's basically owner-driven because it cuts costs, eliminating an entire cable and conduit loop since both systems are monitored and controlled over the same cables. Also by allowing fire-alarm systems to be monitored off site, the building owner does not need a separate security person monitoring at odd hours of the day.
CLARK: And in the not too distant future, users will be able to receive e-mails of alarm and trouble events on wireless devices.
SHORT: Another factor contributing to the need for greater system integration is the increasing popularity of green building design, which often incorporates large quantities of natural light. Since glass atriums are an ideal way to do so, the integration of fire-alarm systems and HVAC smoke-control systems becomes necessary. For example, beam-type detectors can be equipped with addressable control modules that are integrated into the smoke-control fans. Should the beam detectors sense any type of smoke in the atrium, they signal for the HVAC smoke control system to start up.
CLARK: There's definitely a demand for centralized command and control, especially in larger buildings. More and more, we find that the specification of the BACnet protocol is finally taking hold. Owners seem to want one-line responsibility for service of all of their building systems including HVAC, security/CCTV, card access and fire. This requirement is pushing manufacturers toward complete integration. Sometimes this is proprietary, depending on the manufacturer, and sometimes it is an open architecture using published building communication protocol standards such as BACnet or Echelon's LonWorks.
Some of the limiting factors revolve around standards issues. While customers may want to integrate their systems, the local authority having jurisdiction usually requires UL-listed components. As an example, if the fire-alarm system manufacturer offers a UL-listed BACnet gateway that permits fire signals to be transmitted to another manufacturer's HVAC system, it is only UL-listed with the fire system, not the HVAC system. Therefore, the entire system may not meet UL requirements since the dampers and fans are not cross-listed as UL-864 devices with the fire system. It is possible that the only answer is for the HVAC manufacturer is to submit their devices to UL for cross-listing with the fire manufacturer's HVAC system. But this is an expensive proposition.
MOORE: I agree that integration is the buzzword floating about the industry, and it is indeed occurring, but it should be noted that system complexities and attendant costs that result from complete building systems integration seem to be dampening the desire to "totally" integrate all building systems.
Total building systems integration will be driven primarily by perceived cost savings, but the fear of putting all of the eggs in one basket—without assurance that a single fault won't take down critical systems—will continue to slow total building systems integration.
HEIN: It takes education, including the authority having jurisdiction. The major system providers are now all offering some level of integration, and by educating the AHJs, who have traditionally resisted integrating these functions, we have seen a mind change. Moreover, many AHJs have expressed an unforeseen benefit to integrating fire systems since most security systems are active, rather than passive, making maintenance a high priority.
CSE: On the subject of education, what are some common pitfalls engineers and building owners encounter when it comes to designing and utilizing fire alarm systems?
MOORE: Not understanding the limitations of the detection portion of the system. Second, not informing owners that the building codes traditionally require only partial detection, and that required limited detection—in other words, just meeting the code—may not meet the owner's fire-protection goals.
Finally, a common engineering error is assuming the equipment can make up for mistakes in the design process.
Owners, on the other hand, often make the assumption that the AHJ will ensure that the fire-alarm system will be installed properly. The AHJ is not responsible for monitoring the quality of the installation, nor is he or she responsible to enforce the specifications of the design engineer.
CLARK: In our experience, most problems occur when the project is design-build, rather than driven from a specification. Having said that, we have also seen projects where the specification called out Class A wiring, but the electrical designer never provided a return conduit path. It is truly amazing how weekly progress and informational meetings can make or break the project.
Sometimes problems can come out of left field, when the architect objects to the color or design of a device that may destroy the aesthetics.
SHORT: Back to the notion of codes. In some states there can be contradictions. For example, in Pennsylvania, the ANSI/BOCA code indicates that sprinklers must be installed in the elevator shafts of all buildings that are "fully sprinklered." However, the Pennsylvania Elevator Code does not allow anything in the elevator shafts. To resolve this issue, a variance must be obtained from the state in order to install the system per ANSI codes.
Another common pitfall is inadequate quantities of audible indicating devices. The NFPA and ADA requires that the audible level of fire-alarm signals be 15 dB above the ambient level for the area. Many times, designers do not show enough audible horn devices to produce this output in higher ambient sound areas such as manufacturing facilities. In facilities requiring voice evacuation systems, engineers often install an inadequate number of speaker devices which creates inaudible voice evacuation messages.
William J. Short, P.E., Electrical Project Engineer, Bala Consulting Engineers, Wynnewood, Pa.
Wayne Moore, P.E., FSFPE, Director of New England Operations, Hughes Associates, Inc., Warwick, R.I.
Pete Clark, Vice President of Marketing Honeywell, Northford, Conn.
Steve Hein, Vice President of Marketing, Edwards Systems Technology, Philadelphia
Fire-alarm control panels, which are now fully addressable, have advanced to become an intelligent system that allows individual addresses for each device. The front-end control panel can narrow the location of an alarm down to the very spot that the respective detector alarmed. New technology also enables the panel to poll up to five times faster than before. Further, the addressable fire-alarm control panels can digitally adjust the sensitivity of detectors to compensate for any dust or debris that may accumulate on them.
Specific advances include the following:
Multisensor technology. This type of sensors can distinguish between a legitimate change of state and a non-threatening situation that would otherwise lead to false alarms. Each sensor is equipped with an on-board microprocessor and is capable of performing many basic digital computing operations reducing the cost of cable installation.
Harsh environment type detectors. Similar to air-sampling type detectors, these detectors, employing a laser, can provide very early warning of slow smoldering fires at lower installed costs. The harsh environment detectors have a small, built-in intake fan that draws air across a filter into a photoelectric sensing chamber to provide active smoke detection. These types of detectors reduce the number of nuisance alarms common in harsh environments.
Visual strobe technology. Now featuring self-synchronization, this innovation allows all devices in an open area to flash in sync in the event of an alarm. This is a requirement of the Americans with Disabilities Act.
Field-adjustable candela (cd) level dipswitch. An offshoot of visual strobe technology, these devices help meet NFPA and ADA strobe standards for devices installed in areas ranging from 15 to 75 cd. The field-adjustable dipswitch allows the designer to specify one type of strobe device with the contractor setting the proper cd output for the proper field application.
Performance-Based Design & the Code
Perhaps the most significant change affecting fire alarm specifications that ripples through the codebook are the references to performance-based design. New guidelines have been added to the 2002 NFPA code that call for applying this design approach. Each performance objective must be documented in an approved format together with calculations, modeling or other technical issues that can be used to establish fire and life-safety performance. The code also directs approval of such designs to the local authority having jurisdiction.
Areas related to performance-based design include:
Audibility. Use of analysis and design to permit audible signaling to comply with masked threshold requirements in lieu of the prescriptive requirements (7.4.5).
Performance-based visibility. Language was added for a performance-based alternative for visible signaling design (188.8.131.52).
Other significant code changes that affect specifications are:
Requirements for survivability of circuits (184.108.40.206) are now applicable to both audible and visible notification appliance circuits. As stated above, the local AHJ can approve performance alternatives to stated requirements.
The new audible notification appliances in stairwells (220.127.116.11) section requires separate speaker circuits to stairwells and permits only manual selective paging.
Sleeping area minimum sound levels have been raised to 75 dBA at pillow (7.4.4).
Other parts of chapter 6 include new requirements for integrated systems, including devices found on modern networks such as routers and servers. The new code addresses recent advances in computerized fire-alarm systems and other combined systems.
Fire Alarm Design Software, A Vision
One noted trend in the world of fire-alarm system design is the number of software packages that have begun to hit the market. Some are as simple as basic quote packages with manufacturer's data filled in, while others are very sophisticated programs that provide smart front-end to high-end CAD systems.
The ultimate scenario would be for the fire system designer to lay down the NFPA symbols on a CAD layer called "fire." The manufacturer's branch or distributor accepts the CAD format and then modifies each symbol with either a smart block (AutoCad) or a Visio SmartShape. The benefit of a data attribute is that a complete list of data fields can be supported. This means that programs can automatically generate bills of material, based on the graphic element of a detector or fire device. If the device is a horn or strobe, the candela and current draw can be automatically computed and the power supply sized appropriately. Eventually, programs will be smart enough to automatically calculate the wire footage, type required, conduit lengths, address of the device and so on. Sales proposals can automatically collate and include complete submittal items such as the manufacturer's data sheets and accurate pricing.
In the scenario described above, the fire designer, architect or engineer would receive back the "fire" layer with all the smart blocks loaded with the attributes. If the proposal is accepted, the fire alarm supplier could even print off "as-builts" based on the final accepted drawings.
What does this all mean to manufacturers and specifiers? It permits the bidding entity to design systems more efficiently and provide more accurate bids with faster turnaround on proposals and the opportunity to bid on more projects. While design systems exist for audio and lighting packages, and while some larger bidding contractors have developed their own proprietary systems already, we should see completely automated fire design quoting and proposal packaging systems within three years.