History and Overview
Photo courtesy of bryantx.gov
In the United States, the first fire detection system was implemented in the mid-1600s in New York City. Designated persons would traverse the city carrying a bell and bucket. If they spotted a fire, they would ring the bell to alert nearby citizens and attempt to extinguish the fire. This method was better than nothing, but the results, as one might imagine, were not very effective. Later advancements over the following centuries included:
- A fire alarm box where someone cranked a handle that notified the fire department (mid-1800s)
- A purely electrical fire alarm box that only required pulling a handle to advise the fire department of the fire (late 1800s)
- Battery-powered smoke detectors which were the forerunner of the smoke detectors used in homes and business today (mid 1900s)
Currently, there is a vast array of fire detection systems available to fit almost every fire risk. They can further be programmed to carry out a myriad of functions that help contain the fire, manage smoke, etc. Modern fire detection systems include, but are not limited to, installations of one or more of the following:
- Various types of smoke detectors
- An assortment of heat detectors
- Flame detectors
- Flammable or explosive gas detectors
In some instances, the fire detection system can be integral to the fire suppression system. This is particularly the case in sprinkler systems and some models of condensed aerosol systems.
Which codes and standards apply to fire detection systems?
For large-scale facilities such as petrochemical plants, hospitals, and large retail centers, the proponent (builder, owner, property manager, etc.) will often engage the services of a certified fire protection engineer. The engineer will be intimately familiar with all applicable codes and standards.
For smaller installations, a reputable and certified installer will also be required to adhere to National Fire Protection Association (NFPA®) codes and standards[1] as well as other applicable local fire codes and Occupational Health and Safety Administration (OSHA) standards.
In addition to NFPA, OSHA, and AHJ (Authority Having Jurisdiction) requirements, in many instances the insurance company covering the risk may have fire detection system conditions. Failure to meet fire detection system conditions specified in the policy can result in a claim being denied in the event of a fire-related loss.
There are several factors to consider when designing a fire detection system for a residential, commercial, or public occupancy. “Occupancy” in this context refers to the use of the structure(s). These factors are defined in NFPA 101 – Life Safety Code®. Furthermore, installed systems must conform to NFPA 72 – National Fire Alarm and Signaling Code®, NFPA 70 – National Electrical Code®, and OSHA 1910, Subpart L. There may also be local fire codes that supersede NFPA codes/standards. Local fire codes are mandated and enforced by the AHJ.
For installations in hazardous areas, OSHA 1910, Subpart S requires that detection equipment be certified for use in said hazardous areas. NFPA 70, Chapter 5 provides detail about the classification and division designation of hazardous areas. In brief, a “hazardous area” is a location where: flammable gases and/or vapors may be present in ignitable quantities; combustible dusts are present (e.g., grain silos); or fibers which can ignite easily are present or processed. Meeting the requirements of these codes and standards is not optional. Additionally, the codes and standards are a great resource in fire detection system design.
What are the components of a fire detection system?
A fire detection system includes several components:
- Fire Alarm Control Panel/Unit
This component contains the electronics which receive the signal from initiating devices. The control panel will/can perform one, more, or all (depending upon the system) of the following functions:– Activate the notification device(s)
– Transmit signals to off-site monitoring stations (if so equipped)
– May automatically activate fire suppression systems
– May be programmed to control elevators, HVAC systems, fire doors, dampers, and locks - Initiating and Detection Device(s)
These devices activate a fire detection system as follows:– Manual – Someone activates a pull-station
– Automatic – Operates without human interaction
Automatic devices include detectors of: smoke, heat, flame, fire gas(es), and even activated fire suppression systems in some instances. This equipment sends a signal to the fire alarm control panel/unit. - Notification Devices
This is how occupants are notified of the fire. NFPA defines four types:– Audible – An alarm tone or bells sound and may include pre-recorded messages over a public address system
– Visual – Strobe lights activate
– Textual – A scrolling or flashing message is displayed
– Tactile – Used for people that are blind and deaf or have significantly diminished sight and hearing. They typically consist of a device that vibrates or shakes. - Signaling Devices
This describes where the alarm signal is transmitted. For example:– Local Alarm – The alarm sounds only on the premises.
– Central Station – The alarm is sent to an independent alarm-monitoring business that in turn notifies the fire department.
– Proprietary – The alarm signal is communicated to an onsite, proprietor-owned location which then notifies the fire department.
– Fire Department Monitored – In some locales, the alarm signal is sent directly to the fire department.
Fire detection systems are critical components to protect life and property. They should be included in any new construction, major renovation, or retrofitted in situations where they do not exist. The detection system options currently available all but guarantee that there is a fire detection solution for every risk. To ensure the most appropriate system is selected, it is vital to consult applicable codes and standards and use high-quality equipment installed by reputable professionals.
To access the companion article Designing a Fire Suppression System, click here.
Sources
[1] Codes dictate minimum requirements that can be converted to law by the AHJ (Authority Having Jurisdiction), whereas standards dictate how a system should be designed, built, and tested.