Duct Detector Sampling Tube Requirements

There should be 10 to 12 holes spaced as evenly as possible across the width of the duct.

Duct detector sampling tube requirements.

The holes must be facing into the air flow see figure 2. The holes must be facing into the air flow see figure 2. Dst1 1 to 2 ft. Dst5 8 to 12 ft.

The sampling tubes may be ordered to a desired length or ordered in one of 3 standard lengths and cut per requirements. Dst3 4 to 8 ft. The sampling tube should be angled at least 1 4 downward for every 12 of duct width per figure 4. Prior to the installation of the damper and smoke detector.

Sampling tubes recommended for different duct widths. Dst1 5 2 to 4 ft. Dst5 8 to 12 ft. If the detector is.

Usually installers provide sampling holes on a two foot grid in two directions over the face of the grille to meet this requirement. Dst10 2 piece must extend a minimum of 2 3 the duct width. The equivalent duct diameter for a rectangular duct is the diameter of a circle that results in the same area as the rectangle. For proper air sampling duct pressure should be a minimum of 0 01 inches of water.

Nfpa 72 recommends but does not require that duct smoke detectors be located in a duct section that is between 6 and 10 equivalent duct diameters from bends or openings. Sampling tubes recommended for different duct widths. In multi story buildings at each story with a commonly shared return and having a capacity greater than 15 000 cfm s. Dst1 1 to 2 ft.

Outside duct width sampling tube recommended up to 1 ft. The physical location of the detector in each room should ensure the detector is readily accessible to view the smoke conditions in the room and for easy servicing. Dst3 4 to 8 ft. Dst10 2 piece must extend a minimum of 2 3 the duct width.

Duct detectors smoke detection nfpa 90a code requirements in air supply systems with a capacity greater than 2000 cfm s downstream of the air filters and upstream of any branch ducts. The intake sampling tube consists of a piece of steel piping with a series of holes drilled the entire length of the tube and should extend the entire width of the duct. The intake sampling tube consists of a piece of steel piping with a series of holes drilled the entire length of the tube and should extend the entire width of the duct. The inlet sampling tube is to be located between blades to avoid blockage of the airflow past the tube.

Outside duct width sampling tube recommended up to 1 ft. The sampling tubes may be ordered to a desired length or ordered in one of 3 standard lengths and cut per requirements. The duct smoke detector is designed for use in duct applications where temperatures can exceed standard detector capabilities. If there are more than 2 holes in the section of the tube extending out of the duct select a shorter tube using table 1.

These sampling tubes can only be used with new innovairflex duct smoke detectors. Air is introduced to the duct smoke detector s sensing chamber through a sampling tube that ext ends into the hvac duct and is directed back into the ventilation system through an exhaust tube.