Size Does Matter
Are your duct smoke detector sampling tubes the correct length for your commercial ducts? IMC (Chapter 606.3) and NFPA 72 (Chapter 5.16.5.2) codes require that all smoke detector installations, tests and inspections are made in accordance with the manufacturer’s published instructions. In most cases, manufacturer specs call for the air sampling tube to extend between 2/3 and 80% of the duct width. If the sample tube does not span the width of the duct, smoke can bypass the sample tube and avoid immediate detection, allowing the fire to progress and placing all those who rely on the smoke detection system in danger. In addition to this potential liability, improperly sized sampling tubes can result in failed inspections, increased job costs and jeopardized inspector relationships.
Some manufacturers supply sample tubes with duct smoke detector purchases. However, the standard sample tube supplied is approximately 12” in length, meaning it is only code-compliant in ducts up to 18” wide. Particularly in commercial applications, where duct widths are more commonly 36 inches wide, the supplied sample tube would not meet code. Download a copy of our tri-fold brochure for further information and an illustrated explanation of why the size of the sample tubes DOES matter!
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