Duct Detector Requirements and Testing
No Tie-In Needed
Q:
My company is installing a fire alarm sprinkler supervisory panel (DACT) with one outside horn, one smoke detector and one manual pull box. We will be connecting to switches installed by the sprinkler company for monitoring the supervisory devices (water shut-off valves) and waterflow alarm switch. The inspector stopped by and told one of our installers that we have to tie in the duct detectors, too. Is this correct? Also, I have supplied my installers with the new International Building Code (IBC). They want to know where the rules are found for testing duct detectors.
—Heidi G. Sheik
A:
No you do not have to tie in the duct detectors. You are installing equipment to comply with the “907.4 Sprinkler System Monitoring and Alarms” section of the IBC. Since the requirement for tying in duct detectors is in 907 “Fire Alarm and Detection Systems,” the duct detector rule (907.11) doesn’t apply to what you’re doing.
To understand how the IBC and IFC (International Fire Code) work, start by reading the “Scope” of the Fire Protection Systems section (Chapter 9) of the IBC. At the very beginning, IBC 901.1 states that this code covers the “application, installation, performance and maintenance of fire alarm systems and their components.”
“Application” tells you where fire alarm systems are to be installed. “Installation” lists the equipment/devices and building locations where they will be mounted. “Performance” means that certain measurable objectives are to be met, such as audibility and visibility. “Maintenance” is only included by reference, because in Section 907.19 the IBC sends you to Chapter 9 of the IFC for the actual testing and maintenance requirements located in that code.
The IFC requires compliance with the testing and maintenance chapter of NFPA 72. In fact, all the IFC Section 907 rules are the same as in the IBC, except for the additional testing and maintenance rules.
As far as scientific methods for testing these devices, first, you must comply with the IBC/IFC as referenced in NFPA 72. Once in NFPA 72 (the National Fire Alarm Code), turn to the Testing and Maintenance” chapter. Under the “Test Methods” table, scan through the list until you find “Initiating Devices,” then “Smoke Detectors” then “Duct-Type.”
Specifically for duct detectors, the test method table states, “Air duct detectors shall be tested or inspected to ensure that the device will sample the air stream. The test shall be made in accordance with the manufacturer’s instructions.”
A manometer or Magnehelic gauge is used to test the pressure differential across the sampling tubes. These gauges have two small hoses that connect on each side of the detector housing; one is labeled Low and the other High. The Low hose is connected to the exhaust tube. The High hose is connected to the sampling tube. Once connected, the gauge will give you a reading indicating the pressure differential between these two tubes. In the example below, the pressure differential between input sampling tube and exhaust tube should be greater than 0.01” of water and less than 1.2” of water.
Greg Kessinger, SET, CFPS, president of an alarm installing company since 1981, teaches NICET training classes to fire alarm system designers and installers and continuing education seminars for Ohio’s fire alarm inspectors. You can reach him at 888-910-2272; e-mail: [email protected]; or visit his website at www.FireAlarm.org.
