What all are the standards need to follow for the installation of duct smoke detectors
Check into NFPA 90A Standard for the Installation of Air-Conditioning and Ventilating Systems for installation requirements. Chapter 6.4 covers locations for duct smoke detectors used for automatic fan shutdown, and also lists exceptions/exemptions.
Also, check NFPA 72 National Fire Alarm and Signaling Code for specific installation requirements in Chapter 17.7.4.
Much of the installation will depend on what the duct detectors will be used for.
I am sure that people get tired of hearing this but it really depends. The first step is to check with your local Authority Having Jurisdiction so see which codes and standards they have adopted. NFPA 90A provides requirements based on the type of system (supply / return) and the system capacity. For supply air systems with a capacity greater than 2,000 CFM you will find that a duct-mounted smoke detector is required downstream of filters and ahead of any branch connections in the supply system. For return air systems with a capacity greater than 15,000 CFM and serving more than one story duct-mounted smoke detectors are required on both the supply air and return air system and at each floor served by the return air system (2018 NFPA 90A, Chapter 6, Section 6.4.2 (Location) Subsection 220.127.116.11).
Conversely, the International Mechanical Code, 2018 Edition in Chapter 6, Section 606 (Smoke Detection Systems Control), Subsection 606.2 (Where required) proscribes detector installation in the return air duct of return air systems having a capacity of greater than 2,000 CFM, in return air risers that serve two or more stories and serve any portion of a return air system having a capacity of greater than 15,000 CFM with the additional requirement of detectors at each story upstream of the connection between the riser and any duct or plenum. Additionally, detection is required in common supply and return systems having a capacity greater than 2,000 CFM with exceptions.
This is for air systems only. As Christopher wrote it also depends upon what the intent of the detector installation is (damper actuation versus systems control).
Once again check with your local Authority Having Jurisdiction to avoid doing the work twice.
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