A working fire alarm system isn’t generally a newsworthy event - yet the method utilized here is.
Advantages of intelligent designAn increasingly popular decision is to bring specialty contractors in for consultation during the design phase.
No, this isn’t a religious comment. An increasingly popular decision is to bring specialty contractors in for consultation during the design phase. This allows experienced hands-on construction representatives to share their opinions while having them validated and integrated by the design professionals. In this instance, AMFES was brought in early on to discuss the fire alarm system and how it would impact the building - and what cost savings options could be considered. Several key items were discussed in these early phases and approval was granted for multiple changes - with substantial anticipated cost-savings.
Duct detectors are an (un)necessary evilif an area smoke detection system protects the area served by the air handling system, that area detection system may be substituted for the duct detection
The mechanical code has long had entries for “duct-mounted smoke detectors”, also known as “duct detectors” or even “ductectors” in industry shorthand. While they can take different physical forms all versions of these products are intended to accomplish the same function: detect smoke in the air ducts. The mechanical codes require duct detection be installed for air handling systems of a particular size, e.g. 2000cfm, and/or at protected penetrations of smoke barriers by ducts, i.e. smoke dampers. However…the mechanical codes also have an exception: if an area smoke detection system protects the area served by the air handling system, that area detection system may be substituted for the duct detection.to avoid this means having the air ducts and heating coils cleaned - NOT the duct detector, even though the duct detector appears to be the problem
This exception offers tremendous potential for two reasons. First, if area smoke detection is either already mandated for other code reasons or can be added for less than the cost of the duct detectors - then an immediate cost savings can be realized in the installation. The other reason is duct detectors are inherently false-alarm prone. Simply because the air-handling system is forcing the air through the detector - dust builds up. This leads to trouble conditions (when the detector and the system it is connected to are capable of alerting on a dirty status) and false alarms. The other problem comes from usage. The majority of air-handling systems today are used both for heating and cooling. In climates like Las Vegas, the heater is often used for only a small portion of the year. This means anywhere from six to 10 months of no heater usage - which means lots of buildup on the heater. When the heater is finally turned on for the first time - all that crap starts to cook off, generate smoke (albeit small amounts that may be invisible to the human eye), and falsely activate the duct detectors. Attempting to avoid this means having the air ducts and heating coils cleaned - NOT the duct detector, even though the duct detector appears to be the problem. Whereas area smoke detectors are nearly immune to this particular problem, as they are installed in the room being served instead of the confines of the ductwork.
Another issue with duct detectors is the testing, servicing, and cleaning. Typical construction plans acknowledge the requirement for duct detectors to be present for purposes of installation - but do not make allowances for servicing and access after the building is open. All too often units are installed in locations posing significant access challenges - such as small attics, insulation layers, ceiling heights greater than standard ladders, even locations that would mandate, shall we say, technicians of a slimmer girth or reduced height than some?This translates to nearly a $10,000 savings just in the installation - and probably another $1,000 per year in reduced maintenance
Because the IPEC structure already required area smoke detection there was no additional cost to consider. Eliminating all the interior duct detectors that would otherwise serve the smoke dampers saved nearly 30 duct detectors. Additionally, eliminating the duct detectors that would otherwise be on the 20 in-ceiling air-handlers was another significant savings. Only the large rooftop units, serving large common areas that did not require and would have been impractical to protect with area smoke detection retained their duct detectors - and these units are easily accessed and serviced. This translates to nearly a $10,000 savings just in the installation - and probably another $1,000 per year in reduced maintenance.
Speakers are friendlier than horns
Regardless of brand, model, style, size, or complexity, all fire alarm systems have at least one common denominator.
Especially in Nevada - and yet even more so for Clark County. 80dBA minimum throughout - plus a requirement to have a device in EVERY room. Including bathrooms. We’ll talk more about fire alarm notification another time but just to summarize the requirements for this project:
- 80dBA minimum - most teenage rap crap isn’t played this loud.
- Low-frequency tone in sleeping areas.
- Temporal tone pattern.
- Synchronized tone pattern throughout.
- Voice evacuation throughout.
Given the choice, fire alarm speakers are considerably easier on the ears than horns. If only because the pre-recorded message breaks up the blaring tones. But until this installation, accomplishing the above list would have an extremely challenging task. The low-frequency tone had only been established recently and only one manufacturer had a horn approved for such. And not only was it expensive - it wasn’t capable of meeting the 80dBA requirement. And no one had a voice system officially approved to provide the low-frequency tones. In what has become typical of AMFES operations - we created one.No other fire alarm notification system has ever come close to the performance of this one.
Working with Advanced, Gentex, and ETL, the first fully NRTL listed fire alarm voice system was created to meet the low-frequency requirement. And by using a single consistent sound source (the pre-recorded message system), synchronization (the Advanced network-driven synchronized voice), and identical drivers (Gentex SSPK) a single clear message and tone pattern are heard throughout the facility. Pre-recorded alert, test, and all-clear messages further the user-friendly design. Having a clean notification signal ensures that while occupants are alerted to emergency conditions there is no disorientation from conflicting sounds or strobes. In fact, from the open front lobby both the message and the strobes from all three floors can be clearly heard and observed. No other fire alarm notification system has ever come close to the performance of this one.
System smoke detectors vs standalone smoke alarms
For residential occupancies the fire codes mandate smoke alarms. These devices are not connected to the building fire alarm system, do not notify building staff in the even of an alarm or trouble, require their own secondary power source (typically a 9-volt battery), have no automatic supervision to detect and prevent tampering, and are generally not included in the scope of a fire alarm test & inspection agreement. But they are cheap.using creative yet code-compliant wiring methods and additional system components, the speakers (and strobes within ADA-compliant guest rooms) become individually controlled
On the other hand, system-connected smoke detectors can be substituted for standalone smoke alarms. The requirement from a local code standpoint, and typically building management as well, is to ensure the detectors only alarm in the associated guest room - and not activate the building-wide alarm. Simply programming the panel to not activate the building-wide system from these detectors is trivial with an Advanced AxisAX system - but then the question is what form will the local alarm take? The legacy solution would be to use an integrated sounder base for the smoke detector - which was an elegant solution for its time but doesn’t answer the needs of today. Instead, by using creative yet code-compliant wiring methods and additional system components, the speakers (and strobes within ADA-compliant guest rooms) become individually controlled - allowing them to be used both as local-only alarms and for building-wide notification. Thus, the requirements for building-wide notification, temporal pattern, low-frequency tones, voice evacuation, and local alarms are all provided by a single speaker in each room - reducing the impact on the decor.
Post installation analysis
Since completing this installation we’ve had opportunities to review the operation and validate the design. Unquestionably the decision to eliminate the duct detectors was the right one (it almost always is). There hasn’t been a single duct detector issue since the building opening. The voice system has proven itself during inspections to minimize the impact on the tenants and staff. And the in-room smoke detectors have been stable and eliminated the need for building staff to routinely test and verify standalone smoke alarm operation.It’s also appropriate to note that not only are the long-term costs reduced - AMFES was the low bidder for this project by a significant margin. To reap the benefits of having AMFES design and install your system, contact us today!
Relative to major Las Vegas Strip properties the IPEC may not seem like a significant property. Yet the principles applied here are equally valid for larger buildings - indeed, the larger building generally the greater the savings obtained from design decisions such as those used here. It’s also appropriate to note that not only are the long-term costs reduced - AMFES was the low bidder for this project by a significant margin. To reap the benefits of having AMFES design and install your system, contact us today!
Last updated: Sat 24 September 2022