System Sensor Questions Concerning the Installation fo Duct Smoke Detectors

Technical Field Bulletin Questions concerning the installation of duct smoke detectors of System Sensor duct smoke detectors Application Engineers 10 03 1 04 Can a System Sensor duct mounted smoke detector be installed vertically on top of the duct or within the duct Yes but only if the following provisions are met System Sensor recommends the verification of pressure differential between the and exhaust tube be the determining factor The pressure differential must be within specified limits of 0015 to 1.20 for photoelectronic smoke detectors The detector housing cover must be securely fastened to complete the airtight for proper air sampling and to restrict contaminants from entering the detector head A smoke test should be performed as by the NFPA National Fire Protection Association 72 Chapter 10.4.2.2 g4 2002 edition note the operating temperature ranges from 32 degrees Fahrenheit to 120 degrees Fahrenheit maximum and a relative humidity of 10 to 93 Insure that the end cap is installed in the inlet sampling tube and that sampling holes outside of the duct if any sealed regard to the location of the duct mounted smoke detector please note NFPA 72 Section A 5.14.5.2 which states in part In to obtain a representative sample stratification and dead air space should be avoided Such conditions could be caused by return openings sharp turns or connections as well as by long uninterrupted straight runs For this reason duct smoke detectors be located in the zone between 6 and 10 duct equivalent diameters of straight uninterrupted run In return air systems the of 5.14.4.2.2 take precedence over these considerations Can these detectors be installed underneath the duct They can but it is not recommended due to condensation that may drain into the electronic circuitry and cause electrical damage always contact the local Authority Having Jurisdiction prior to installing detectors you have any questions concerning System Sensor products or their application contact Technical Services at 1 800 SENSOR2 736 7672 extension 2 Ohio Avenue St Charles IL 60174 Phone 800 736 7672 Fax 630 377 6583 www systemsensor com