Initiation Devices for Fire Alarm Systems, Part 2
The following article is a continuation of this series.
As I said in my last blog post, the easiest way to understand why we choose one device over another is to look at how each device operates. In Part 1 of this series, I talked about smoke detectors. In this blog post, our focus shifts to heat detection.
Another device that is commonly used in fire alarm systems is a heat detector. There are a few different types of heat detectors. Heat detectors activate when the temperature around the detector reaches or exceeds a certain level. Heat detectors are commonly used in attics or in warehouses. Why use a heat detector instead of a smoke detector? Attics and warehouses can be dusty, and smoke detectors have a hard time telling the difference between a puff of dust and a plume of smoke. Heat detectors in attics and warehouses reduce false alarms significantly.
Duct detectors are a type of smoke detector that are used in the ducting of a HVAC system. The serve to sense smoke in the HVAC system before it spreads to the areas it supplies. The detector works by circulating air through sample tubes past a smoke sensor that’s mounted inside the detector housing. In Texas, duct detectors are required on the supply side of units over 2,000 CFM and on both the supply and return sides of units over 15,000 CFM.
Beam detectors are commonly used in warehouses, lobbies, or large open areas. Beam detectors operate by passing a beam from the transmitter across the protected area to a receiver, which reflects the beam back to the transmitter. When smoke breaks the beam, the detector will go into alarm. In Part 1 of this series, I talked about how some smoke detectors operate by sensing when smoke breaks a beam of light. Beam detectors function using the same principle, they just cover a greater space. For this reason, larger applications will use beam detectors over smoke detectors, if only for the reduced aesthetic impact of the reduced number of devices. Why use six devices when two would do the same job?
Another device commonly used in a fire alarm system is module that monitors the tamper and flow switches of a sprinkler system. The module detects if the water supply for the sprinkler system is cut off at the tamper switch or moving past the flow switch because of an open sprinkler head.
These are not all of the devices that are used on a fire alarm system but they are some of the common devices that are used in fire alarm systems today.
Want to talk to a fire systems expert? Call Ener-Tel. We’d be happy to talk to you about your options.