Your questions answered: Fire and life safety: Notification and communications systems
Questions not answered during the live “Fire and life safety: Notification and communications systems” webcast Oct. 30, 2019, are answered by the presenters
Fire/life safety notification and communications systems are specified for the safety of the building’s occupants in the event of a fire or other disaster. Fire and life safety systems need to be specified, installed, commissioned and maintained, depending on each building type and location. Codes and standards, including the International Fire Code and various NFPA standards, provide design and installation provisions for fire notification and communications systems in the event of a fire or other emergency event.
Emergency communications systems and mass notification systems are critical to any building in order to notify occupants of an emergency and for overall life safety. Fire, smoke, heat, linear and intelligent detection systems are required at varying levels in nonresidential buildings and aid in the notification process. Depending on the building type, different features are necessary to comply with codes and standards.
Questions not answered during the live “Fire and life safety: Notification and communications systems” webcast Oct. 30, 2019, are answered here.
- William Koffel, PE, FSFPE, President, Koffel Associates
- Raymond A. Grill, PE, FSFPE, Principal, Arup
Question: Would a pre-action system be appropriate for a hospital room or space containing an MRI?
Bill Koffel: I would first ask the question as to why a wet pipe sprinkler system would not be acceptable. This is commonly done in the hospitals in the U.S. If there is a concern regarding the accidental discharge of water, then a pre-action system could be used. It should be noted that this will increase initial cost as well as operating costs due to the increased complexity of the system and the additional equipment/devices (e.g., detectors, panel) required for a pre-action system.
Question: What type of detection can be used in a studio 100×130 feet (length by width) by 45 feet high?
Ray Grill: Detection wouldn’t necessarily be required unless it were an owner requirement. NFPA 140: Standard for Motion Picture and Television Production Studio Soundstages, Approved Production Facilities and Production Locations could provide guidance for your situation.
Question: Beam detectors are causing nuisance alarms due to fog introduction. How do we eliminate this problem? This is for a movie/video production studio.
Ray Grill: A studio doesn’t necessarily require smoke detection. NFPA 140 allows detection that is provided to be disabled during times when special effects may cause unwanted alarms. There are criteria in NFPA 140 that would require visual indication at a control point so that alarms can be activated manually if necessary.
Question: What are the criteria for selection and placement of audible notification appliances to meet intelligibility requirements of NFPA 72: National Fire Alarm and Signaling Code?
Bill Koffel: There is no single, easy answer regarding the selection and placement of notification appliances to achieve intelligibility. Experience has clearly shown that using more devices at a lower output improves intelligibility. However, each application requires careful analysis as part of the design process.
Question: By HVAC control, do you mean exhaust fan shutdown as well?
Ray Grill: Exhaust fans are not required to be shut down since they are exhausting air directly to the exterior without the ability to recirculate air or smoke within the building.
Question: Can you address the “capability to support visual notification” in R-2 occupancies? What is the intent? What are common means of compliance?
Ray Grill: This question is referring to the International Building Code requirement that dwelling units in R-2 occupancies (apartments) have the capability to support future visual notification. The IBC allows compliance to include future interconnection of the building fire alarm system with devices in the units. This requirement is typically complied with by having a fire alarm system that can be expanded to drive future strobes within the units in the event a hearing-impaired tenant needs accommodation. Modern fire alarm systems have the capability of being expanded through various means (i.e., power extender panels) to accommodate future strobes.
Question: What are the criteria for the authority having jurisdiction to confirm if the risk analysis is conducted properly to determine if a mass notification system is required or not?
Bill Koffel: Using the SFPE Engineering Guide for Fire Risk Assessment, the AHJ should be one of the stakeholders performing the risk analysis. As such, the AHJ will have input throughout the process and will be able to determine if the analysis adequately addresses the risk. Recognize that disagreement with certain decisions made by the stakeholders does not mean the analysis is flawed.
Recognizing that many risk analyses will be performed without active participation of the AHJ, the AHJ now serves more as a reviewer, just as they do with most design and construction projects. NFPA 551: Guide for the Evaluation of Fire Risk Assessments is a guide for evaluating risk assessments and provides guidance for the AHJ. Additionally, the review would include evaluating each step of the process such as:
- Have the goals and objectives been adequately defined?
- Are the assumptions appropriate and acceptable?
- Have the hazards been properly defined?
- Is the data appropriate and reliable?
- Have the consequences been properly evaluated?
The list continues, but essentially the questions would relate to each step within the process and the SFPE guide provides a good flowchart of the process.
Question: How does the processing of combustible dust impact the requirements for notification systems?
Ray Grill: More information would need to be provided to address this issue. If combustible dusts are present in the environment, intrinsically safe equipment may need to be provided.
Question: Would pathway survivability affect the architectural design to provide fire-rated enclosures or shafts for fire alarm circuits?
Ray Grill: Designing for survivability could impact the architecture. With a distributed notification system, rooms housing amplifiers or other control equipment serving multiple zones could be required to be located in fire rated rooms.
Question: What are the factors to consider in a risk analysis?
Bill Koffel: Please refer to the risk assessment question and response above. There is considerable information in Annex A of NFPA 72 that identifies the factors to be considered. As noted in the response above, the SFPE guide provides additional guidance on performing a risk assessment (risk analysis).
Question: How would you suggest approaching intelligibility in a project where the majority of the space consists of hard surfaces making it difficult to achieve intelligibility? (In other words, most or all of the space would be an acoustically distinguishable space, or ADS.)
Ray Grill: First, a building could have acoustically distinguishable spaces where intelligibility can be achieved and other ADS where it would not be expected to be achieved. In a space where notification is required, and it is known to be an acoustically challenging space, there are a number of different approaches that could be used. The nature of the space and the nature of the occupants needs to be considered:
- Can textual visual signaling in the way of reader boards be used to provide information?
- Can high–quality speakers be installed to provide intelligible voice messages?
An engineering analysis would need to be conducted and the AHJ would need to be on board with the solution.