The fire alarm control panel (FACP), fire alarm control unit (FACU), or simply fire alarm panel is a system component that monitors inputs and control outputs through various circuits. The primary purpose of the fire alarm control panel is to process signals received from initiating devices and to activate appropriate signals and outputs.
Signals Received At The FACP
Fire Alarm Signal: A fire alarm is a signal produced by an initiating device such as a manual pull station, smoke detector, waterflow switch, or other device. Activation of a fire alarm means there is a possible fire in the area of the initiating device.
When a fire signal is generated a few events occur: 1.) the FACP activates the building audible and visual devices (i.e. horn/strobes), 2.) sends a signal to the central station responsible with monitoring the building fire alarm system, and 3.) actuates control of certain building functions (i.e. fan shutdown, elevator recall to ground floor)
When a fire alarm signal is received by operators at the central station, that signal is immediately transmitted to the fire department which is dispatched to the building. The central station operator contacts the building after a signal has been transmitted to the fire department.
What Happens When A Fire Alarm Is Activated
1. Smoke Dampers: Smoke dampers open and close when required to provide fresh air or to stop smoke passage.
2. Fire Dampers: Fire dampers close when a rise in temperature occurs and stay shut to stop fire from passing through a barrier.
3. Elevator Recall: The fire alarm system integrates with elevator controls to recall elevator cars to a designated landing floor in the event of an alarm.
4. Door Release (In Some Systems): The fire alarm system will actuate a relay to release door holders so those doors will automatically close to provide a smoke barrier between two areas.
5. Failsafe Activation: In some buildings there are access doors in lobbies and staircases that are locked for security reasons on a daily basis. The fire system will unlock these doors when a fire alarm is initiated to allow for emergency re-entry into these secured areas. This is most useful for relocating floor occupants from the affected floor to a floor below the affected floor.
Supervisory Signals: A supervisory signal indicates that a system or device being monitored has been tampered with or is in an abnormal state. Supervisory signals are received at the FACP to indicate the supervisory condition needs to be investigated and corrected. Supervisory signals are transmitted to central stations but do not indicate a fire condition. Therefore they are not transmitted to the fire department by the central station operators.
Supervisory signals are generated from initiating devices such as:
- Valve tamper switches on a sprinkler system
- High or Low water level switch on a gravity tank feeding a sprinkler system
- Low air pressure switch from a dry pipe sprinkler system
- When a fire pump:
- is running
- experiences pump failure
- is in pump phase reversal
Trouble Signals: Trouble signals indicate that parts or all of the fire alarm system, transmitter, or communications path is out of service. The fire department is not dispatched to respond to trouble signals. Trouble signals are not indicative of a fire condition. Common trouble conditions monitored by a Fire Alarm Control Panel are battery condition, AC failure, ground fault, open or short circuit on a wire, phone line failure, or internal component failure. A trouble signal will ordinarily annunciate audibly and visually at the Fire Alarm Control Panel to indicate the trouble condition, which needs to be investigated and corrected.
Actions To Take When A Signal Is Received
Acknowledge. An acknowledge button, also abbreviated as (ACK) is used to acknowledge alarm, trouble or supervisory conditions. The sequence and procedures may differ in every fire alarm system; however, it is important for the C of F holder, when present and practical, to report to the FACP location whenever the alarm is activated.
Alarm Silence. The alarm silence switch is used to silence the building audible and visual devices (such as sirens, bells or gongs) after an evacuation is complete while the source of alarm is being investigated. Never reset the fire alarm system until the condition is verified by the FDNY personnel. Depending on the configuration of the alarm system, this function will either silence the system’s notification appliances completely, or will silence only the audible alarm, with strobe lights continuing to flash. However, the silence switch does not prevent a signal from being transmitted to a FDNY approved central station company. Audible silence allows for easier communication for emergency responders while responding to an alarm.
System Reset. The type and number of ways may vary depending on fire system. This switch is used to reset the fire alarm system after an alarm condition has been cleared. All initiating devices should return to normal condition after manually resetting. If an initiating device is still in alarm after the system is reset, such as smoke detectors continuing to sense smoke, or a manual pull station still in an activated position, another alarm will be generated. A system reset is required to clear alarm conditions. A system reset does not clear trouble conditions. After a fire alarm is reset, the fan usually requires restarting from a separate “fan restart” button or key switch.
A FACP indicating an alarm signal cannot be reset to “normal” if the device or devices signaling the alarm to the FACP have not returned to a normal state from an alarm state.