Duct Smoke Detectors and Sprinkler Monitoring Systems

Duct Smoke Detectors and Dedicated Function Fire Alarm Systems

Definitions: Building Fire Alarm Systems VS. Dedicated Function Fire Alarm Systems

Building Fire Alarm System: NFPA 72 2022 3.3.118.4.1 = “A protected premises fire alarm system that includes any of the features identified in 23.3.3.1 and that serves the general fire alarm needs of a building or buildings and that provided fire department or occupant notification or both.”

Dedicated Function Fire Alarm System: NFPA 72 2022  3.3.118.4.2 = “A protected premises fire alarm system installed specifically to perform emergency control function(s) where a building fire alarm system is not required.”  NFPA 72 2022 ANNEX A 3.3.118.4.2 = “Examples of a dedicated function fire alarm control unit include an automatic sprinkler alarm and supervisory control unit or an elevator recall and supervisory control unit.”

Building Fire Alarm System: NFPA 72 2022 23.3.3.1 =” Protected Premises fire alarm systems that serve the general fire alarm needs of a building or buildings shall have one or more of the following systems or functions:”

Manual fire alarm signal initiation

Automatic fire alarm and supervisory signal initiation

Monitoring of abnormal conditions in fire suppression systems

Activation of fire suppression systems

Activation of emergency control functions

Activation of fire alarm notification appliances

In-building fire emergency voice/alarm communications

Guard’s tour supervisory service

Process monitoring supervisory systems

Activation of off premises signals

Combination systems

An example of an application where you shall use a dedicated function fire alarm system is as follows:

An office building with a “B” type occupancy with less than 500 persons throughout or ≤ 100 persons above or below the lowest level of exit discharge.  Based on these factors, a building fire alarm system is not required per the 2021 International Fire Code IFC section 907.  However, per the 2021 International Building Code IBC 903.4 Exception #2, you need to provide monitoring of the sprinkler system if it has ≥ 6 sprinkler heads.  In this case you could install a dedicated function fire alarm system for the monitoring of the onsite sprinkler valves and Waterflow switches.  This dedicated function fire alarm system shall be noted as a “Sprinkler Waterflow and Supervisory System” per NFPA 72 2022 23.8.5.5.1 and 23.8.5.6.1)

NFPA 72 2022 section 23.3.3.2.1 - Dedicated Function Fire Alarm Systems

“In facilities without a building fire alarm system, a dedicated function fire alarm system shall be permitted and shall not be required to include other functions or features of a building fire alarm system.”

NFPA 72 2022 section 23.8.5.4.6.1 – Signal Initiation – Duct Smoke Detectors

“Where duct smoke detectors are required to be monitored and a building fire alarm system is installed, a duct detector activation signal shall meet the requirements of 21.7.4”

NFPA 72 2022 section 23.8.5.6.1 – Supervisory Signal Initiation – Sprinkler Systems

“Where required by other governing laws, codes or standards to be electronically monitored, supervisory signal initiating devices shall be connected to a dedicated function fire alarm control unit designated as “Sprinkler Waterflow and Supervisory System” and permanently identified on the control unit and on the record drawings.”

“Exception:  Where supervisory signal initiating devices are connected to a building fire alarm system, a dedicated function fire alarm control unit shall not be required.”

What can we take away from this information?

We know that Duct Smoke Detectors (DSDs) when required to be monitored are to be tied into a building fire alarm system per NFPA 72 2022 section 23.8.5.4.6.1.  We also know that a dedicated function fire alarm system is in place to perform a specific function and shall not be required to include additional features of a building fire alarm system. Bottom line is if a building fire alarm system is not installed, duct smoke detectors shall be stand alone and are not required to be connected/monitored by a dedicated function fire alarm system.