Ch.7 - Fire Protection Systems

Delia Tacheny
INT 324 - Building Codes
Reading: The Codes Guidebook for Interiors

Keywords:

• Detection System
• NFPA - 72
• Alarm System
• Emergency Communication System (ECS)
• Mass Notification System (MNS)
• Extinguishing Systems

Last week we discussed passive fire protective systems which include various fire-rated assemblies. This week, we learned about active fire protective systems. To review, passive systems prevent and control the spread of fire and smoke; active systems react once a fire has been detected. "The overall aim of the active fire protection system is to detect a fire in a building or space, warn the occupants, and suppress the fire until the fire department arrives." The various active systems reviewed in this chapter correlate to the plumbing, mechanical, and electrical building systems which will be discussed in the following chapters. As always the construction type and occupancy will affect the codes on each project, and depending on these codes, the fire protection system will be either manual, automatic, or a combination. 

Detection Systems

The first part of an active fire protective system is a detection system. Detectors are also known as "initiating devices" because they initiate the rest of the system such as alarms, etc. Detectors help sense the danger of fire and smoke as early as possible. Depending on the detector, it will sense smoke, heat, gases released by combustion, changes in temperature, or other fire signatures. Smoke detectors and heat detectors are the most common types of detector systems. "The NFPA- 72 provides the minimum performance, location, installation, and maintenance requirements for detection systems." It's important to note that detectors should be strategically placed in areas where they will detect a fire if it should occur, but in locations that will minimize the chance of false alarms. For example, placing a detector in the cooking area where standard cooking procedures occur is probably not the best idea. 

A manual fire alarm is technically considered a detector; in contrast to automatic systems, it is the occupant detecting the fire and manually pulling the alarm. Carbon monoxide detectors are another very important detection system, especially in residential buildings.

Alarm Systems

An alarm system is what actually alerts occupants of the detected danger; these are also called "notification appliances." Once again, an alarm system can be manual or automatic. Additionally, depending on how it is connected to the electrical system, the system can be either single-station or multiple station. A single-station alarm will only sound at the device that detected the fire and warn those in the immediate area. A multiple station system is a set of devices that are all interconnected and will all sound when one goes off. Smoke alarms and fire alarms are the two most common systems. "The NFPA 72 and the LSC require low-frequency fire alarm notifications signals in new hotel, dormitories, and other sleeping rooms because they have proven to wake sleeping or hard-of-hearing occupants more effectively."

Alarm systems are required to use both visual and audible signals to alert as many people as possible. "Visual and audible alarms have two modes of notification: public and private. Public mode informs all occupants of the danger. Private mode alerts only occupants who are expected to respond to the emergency. In that case, the alarm notification may be limited to corridors and areas occupied by control staff members." (Ex. A hospital would likely use a private mode alert system because most hospital occupants will not be able to evacuate on their own.) Private system also may allow a designated person/ system to manually prevent the alarm system from going off if a false detection occurs. 

An emergency communication system (ECS) is another layer of communication, sometimes added to a fire alarm system. "According to the NFPA 72, an ECS is defined as 'a system for the protection of life by indicating the existence of an emergency situation and communicating information necessary to facilitate an appropriate response and actions.'"

A mass notification system (MNS) is often seen on schools, college campuses, and industrial complexes, as it sends a mass notification to individuals, providing real-time information and instruction as to what to do in response to an emergency whether it be weather emergencies, active shooters, terrorist threats, etc. We have an MNS here at Judson, so in cases of emergency we receive emails and texts informing us on what to do. 

While additional accessible warning systems are available for use, neither the ADA or building codes require these at the moment. The current codes for active protective systems are already universally accessible for the most part. 

Extinguishing Systems

Once a fire has occurred, extinguishing systems are necessary to control a fire.

Fire extinguishers are extremely common, and the codes require them in certain spaces and within easy accessibility. There are four classes of fire extinguishers in range from least hazardous fire locations to most: Class A, B, C, or K fire hazard (they have distinct colors/shapes to label the difference.) A fire extinguisher, typically recessed within a wall, cannot protrude more than 4" into the path of travel, and they are typically placed by doors and means of egress.

Standpipes and fire hoses are typically installed in the beginning phases of building construction, and they provide water in case of a fire. There are three different classes of standpipes for varying intended uses by either firefighters or by limited building personnel trained in its operation within the building. There are also five different system types: Automatic wet, automatic dry, manual wet, manual dry, or semi-automatic dry. 

Last but not least, sprinkler systems are vital and very effective extinguishing systems -- some are even required in residential homes. And... if you remember from our previous chapters on occupancy and construction types, having a sprinkler system has beneficial trade-offs such as more allowable building square footage or height. There are various types of piping systems (similar to above) as well as various sprinkler head types that are best for different types of locations and ceiling construction. 

Source(s):

Kennon, Katherine E., and Sharon Koomen Harmon. “Ch.7: Fire Protection Systems.” The Codes Guidebook for Interiors, John Wiley & Sons, Inc., Hoboken, NJ, 2022.