Your questions answered: Fire and life safety: Specifying fire detection and notification systems

The Oct. 26, 2017, “Fire and life safety: Specifying fire detection and notification systems” webcast presenters addressed questions not covered during the live event.

11/01/2017


Fire detection and notification systems are specified for the safety of the building’s occupants in the event of a fire. 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 detection and notification systems in the event of a fire or other emergency event.

Questions not addressed during the Oct. 26, 2017, “Fire and life safety: Specifying fire detection and notification systems” webcast are addressed here.

Presenters:

  • Raymond A. Grill, PE, FSFPE, principal, Arup, Washington, D.C.
  • David Lowrey, chief fire marshal, Boulder (Colo.) Fire Rescue

Question: What standard will be used in specifying fire detection and alarm?

David Lowrey: NFPA 72 covers the application, installation, location and performance for fire detection and alarm. In other words, NFPA 72 tells you “how” to install and “how” the fire alarm system will operate. When a fire alarm system is required will be determined by the adopted building or fire code within that jurisdiction.

Question: Do you for see a greater shift in the future toward audio evacuation?

Lowrey: I do see a shift and an increased use in Voice audio for evacuation. I believe we saw this beginning in the 2012 International Fire Code where certain Group A occupancies and Group E are now required to have a voice system.

Question: Are LED strobes allowed?

Raymond A. Grill: Yes, NFPA 72 2016 edition, Section 18.5.3.2 specifics the light pulse duration and duty cycle for the strobe. The stated pulse duration and duty cycle actually limits the strobes to Xeon tube strobes. However, an exception has been included that allows strobes to operate with a greater pulse duration if you’re using Section 18.5.5.5 “spacing in corridors.” This exception was specifically included to allow LED Strobes.

Be aware that different manufactures may have LED Strobes that are now listed which meet the required pulse duration from section 18.5.3.2 which would be allowed with any design.

Question: Do you know of a guide that identifies ambient levels typical for different spaces; i.e. general lab space before it is occupied?

Grill: There is some guidance in Annex A of NFPA 72. Table A.18.4.3 provides average ambient sound levels for different occupancy types. While this table provides some guidance, there can be a wide range of ambient sound levels depending of the nature of the operation and potential noise sources associated with normal activities within the space. When designing for audibility, particularly in an industrial or laboratory environment, it would be best to be able to get ambient sound pressure level readings from a facility with similar operations.

Question: Can you give some advice on measuring ambient sound levels and how long the test should occur?

Grill: NFPA 72 actually provides a definition for average ambient sound in Chapter 3. It notes that the average should be evaluated over the time period when people are present or a 24-hour period, whichever is less. Basically, if you have a use that is operating 8 hours a day, you would determine the average ambient over the 8-hour period. Practically speaking, if you are evaluating the ambient sound in an operating facility where there isn’t much fluctuation in ambient sound, the duration of the evaluation could be reduced. The key is that adequate audibility be provided by the system in an emergency. If you had a facility that had a broad fluctuation in ambient sound levels, designing to the average which has been determined over a long time period may not provide very good signaling during the peak ambient sound levels. Engineering judgement should be applied in these cases.

Question: In a high-rise building, when is a class A system required?

Grill: The model building and fire codes (IBC, IFC, NFPA 101, NFPA 1) do not prescribe a specific classification of fire alarm circuit. Some jurisdictions require Class A circuits for risers in high-rise buildings. The General Services Administration in PBS P-100 requires risers in high-rise buildings to be Class X. The requirement for either Class A or Class X circuits is typically an owner driven requirement. These strategies could be part of a performance based solution for meeting survivability requirements in a high-rise building. This would be subject to approval by the authority having jurisdiction.

Question: Explain the emergency power sources required by code?

Grill: NFPA 72 requires a primary and secondary power supply for a fire alarm system. If an uninterruptible power supply (UPS) designed and installed in accordance with NFPA 111 is provided, it can be the only supply. A UPS would have to be Type 0, Class 24, Level 1 as defined by NFPA 111.

The traditional method is to provide a primary and secondary power supply. The primary power supply is typically the normal light and power service for the facility. The secondary power can be either batteries or a generator. If a generator is provided, at least 4 hours of battery power are required to be provided.

Question: Can FACP batteries be utilized as emergency power?

Grill: Batteries that are provided as part of the fire alarm system are not typically sized to supply other emergency loads. A centralized battery bank could be designed to supply the fire alarm system and other emergency loads provided the criteria for standby batteries in NFPA 72 were provided and the arrangement was acceptable to the authority having jurisdiction.

Question: What capacity or charging rate required to meet NEC 700 requirements?

Grill: NFPA 72 specifically requires that the battery charging equipment be capable of recharging the batteries within 48 hours. See Section 10.6.10.3.2 of the 2016 NFPA 72.

Question: How are evacuation notification directions being handled for deaf individuals when in rooms alone?

Lowrey: NFPA 72, Section 18.9 address the use of textual and graphical visible appliances Section 18.10 address the use of tactile appliances. Either can be used for a hearing-impaired individual to notify them of an emergency however it is the building/business owners responsibility to provide this notification for their employee who is hearing impaired.

Textual and graphical visible appliances are devices that provides notification in a written (textual) or some type of graphical appliance that can be seen. Tactile appliances are devices that alert by a touch or feel (pager that individual might be wearing).

Question: Your codes included several NFPA standards, but I understand that NFPA requirements did not apply unless adopted by the state or the county. Is this true?

Lowrey: Yes, the code must be adopted within the jurisdiction.

Question: Can you describe what is required and best practices (equipment and function) for design related to elevators?

Lowrey: Elevator operation is outlined very specifically in NFPA 72, Section 21.3 – 21.6. 



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