Halon Fire Alarm System

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Last Updated Jan 2001

Copyright © 2001 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

The GSSS work area, plate vault, and GAMMA rooms are on a separate fire alarm system from the rest of the building. Because the plates are susceptible to water damage, a halon system has been installed in these areas. The control panel for the system is located next to the door to room 133. The following is a description of what the different alarms mean as well as the procedures to be followed in an emergency situation.

Positions of Detectors

The detection system is divided into two zones: zone 1 is room 133, and zone 2 is the plate vault area including the GAMMA rooms. The positions of the detectors are shown on the annunciator panel, located next to the control panel.

Sequence of Events

The detectors are sensitive to burning particles in the air, rather than to heat or smoke. If one detector is activated, it will trigger the associated alarm as well as the general alarm for the halon system. Both of these will sound as continuous bells. It will in addition trigger the building alarm, which notifies the fire department. The light on the annunciator panel which corresponds to the activated detector will light up, and the "Alarm" indicator on the control panel will light. Furthermore, air handler #8, which serves the plate vault area, will shut down.

The activation of a second detector in the same zone will cause a steady horn to sound. This is the signal that the 30 second time delay for the halon dump has been initiated. Note that the second detector must be located in the same zone in order for this second stage to begin: if one went off in the plate vault and the other in rm. 133, the system would remain in the first stage.

At the end of the 30 second delay, the halon dump will be activated. The alarms will change to pulsing horn and bells. The halon will be released from the ceiling nozzles at roughly 300 lbs. pressure over the course of 10 seconds. Once the dump is completed, the concentration of halon in the room will be approximately 6%, and it will hinder combustion.