Your questions answered: Fire/life safety: Detection, notification, and suppression

Both active and passive fire protection systems are specified to ensure the safety and well-being of building occupants in case of a fire. Engineers should be aware of the contents and intent of the building when specifying fire detection, notification, and suppression systems.

By Ray Grill, PE, FSFPE; and Erik Anderson, PE March 9, 2016

Ray Grill, PE, FSFPE, Principal, Arup, Washington, D.C., and Erik Anderson, PE, Manager, Koffel Associates, Columbia, Md., present additional information about protecting the occupants of buildings from the effects of fire as well as specifying fire detection, notification, and suppression systems.

The March 3, 2016, "Fire/life safety: Detection, notification, and suppression" webcast presenters addressed questions not covered during the live event.

Question: Is there any degradation to the alarm system when used for general announcements?

Ray Grill: There should not be any degradation in the system just by making general announcements. A general announcement is no different than an emergency announcement. Using the system during normal operations is a great way of knowing if the system is operating properly. In the "old days," the building codes used to allow public address systems to be used for fire emergency messages in shopping malls, for example. The codes were changed to require systems to be listed for the purpose. There was no real justification for this other than the public address systems did not have the same level of supervision and the products were not tested by the nationally recognized testing laboratories to the same extent. Fire emergency voice alarm communications (EVAC) systems are robust and should not be degraded by regular use. Because of the level of supervision, if they do degrade, a problem will be recognized during regular use so that action can be taken to correct a degraded condition. As long as the system is maintained, there will be a higher probability of it being able to function as intended in an emergency condition or situation.

Question: Please provide an update on the use of antifreeze systems.

Erik Anderson: In recent years, there have been reports of fire incidents involving antifreeze systems where a high concentration of antifreeze in the sprinkler piping that, upon discharge, may have had a detrimental effect on the fire incident. Please refer to the NFPA website for guidance on the use of antifreeze.

New antifreeze systems must use listed antifreeze solutions, with a few exceptions pertaining to 13D and ESFR systems. Additional guidance applies to existing systems. Because the availability of listed antifreeze is limited, we would recommend using a different approach for freeze protection, such as a dry pipe system.

Question: Can fire alarm system voice evacuation speakers be integrated with a paging system in a hospital?

Grill: A fire alarm voice system can be integrated with a paging system. The paging system could be a primary means of communicating with occupants as long as it is evaluated and found to be reliable consistent with the allowances in Chapter 24 of NFPA 72-2016: National Fire Alarm and Signaling Code. Issues such as emergency power and redundancy would need to be evaluated. A paging system could also be considered as a supplementary system to the fire alarm system. It would need to be interconnected in a manner such that a failure of the paging system would not impact the performance of the fire alarm voice EVAC system.

Question: Does a clean agent displace O2 in a similar manner as CO2?

Anderson: Most clean agents do reduce the oxygen level. However, clean agents typically also use other fire suppression mechanisms, such as reduction of heat and/or inhibiting the fire’s chain reaction. The extent of oxygen reduction depends on the agent type. A properly designed clean agent system can extinguish a fire with a much higher oxygen level compared to CO2.

Question: Please provide an applicable code and sections that require the entire existing fire protection system to be tested if only one water flow switch is replaced? This situation happens to be in one of New York City Public School Buildings.

Grill: NFPA 72 does not require the entire system to be retested if a single water flow switch is replaced. NFPA 72 Chapter 14 requires all new devices to be 100% tested, and when site-specific software is changed, at least 10% of the exiting devices are also required to be tested to ensure the system still performs the input and output functions as originally designed. If a water flow switch is being changed and it is just a matter of reconnecting the new switch to the existing monitor module, the site-specific software hasn’t been changed. The monitor module is still the same and the activation of the existing monitor module is still performing the same function it performed before the water flow switch was changed. The switch should be tested, but retesting of 10% of the devices should not be required because the site-specific software has not been changed.

Question: As design engineers, how are we supposed to handle vandal-proofing of pull stations or other manual devices in public schools?

Anderson: NFPA 101-2015: Life Safety Code and the International Building Code (IBC) allow the designer to omit manual fire alarm boxes (pull stations) in educational occupancies if the building is sprinkler-protected or if detection is provided in certain areas. If pull stations are provided, we recommend that you specify clear covers over the pull stations with an audible tamper indicator.

Question: Does the Americans with Disabilities Act (ADA) require two-way communications systems in stairwells whether or not the buildings are sprinklered?

Grill: The ADA does not require two-way communication in stairwells. If "areas of refuge" are required by the applicable building code, and the stairwell is being used as the required area of refuge, then two-way area-of-refuge communication devices would be required in each area of refuge.

The IBC and NFPA 101 do not require areas of refuge in sprinklered buildings. However, in this case, a means for two-way communication (known as area of refuge communication) is required between the elevator lobby and a 24/7 manned location. The location can be offsite. This communication system functions in the same manner as the code-required two-way communication in elevator cars to allow a person trapped in an elevator to call for assistance.

Question: When is a standpipe required?

Anderson: Standpipe system criteria are found in the building code. The IBC requires a standpipe system if the floor level of the highest story is more than 30 ft above the lowest level of fire-department access. Other buildings—such as mall buildings, stages, underground buildings, and so on—also may require standpipes.

Question: Regarding "any communication tool can be integrated into a mass notification system," doesn’t the communication tool need to be listed as a part of the overall emergency system?

Grill: All communication tools incorporated into a mass notification system do not need to be listed for mass notification. Examples of devices that can be used to receive mass notification messages include your telephone, mobile phone, computer, television, iPad, etc. Transmission of emails, text messages, etc. and TV warnings of emergencies can be an important part of a mass notification system. Having more than one way of communicating the message to create redundancy can improve the potential for the message being received.

The original intent of a fire alarm system being able to be used as a mass notification system was to have a system that is reliable as the means for initiating communication. There was never an intent by the NFPA Task Group that first wrote the criteria that fire alarm systems needed a separate listing for that function. The listing for mass notification systems was driven by the industry to ensure that other systems that were being used for mass notification that were not fire-alarm-listed be evaluated for integrity and reliability. That has led to fire alarm system manufactures also getting their fire alarm systems listed for mass notification so they have dual listings.

Systems or devices that receive emergency messages can be considered supplemental and are not required to be listed for mass notification.