Duct Detector requirments...

[hansolo612]

Hey all,

Just curious, anyone remember where the code (NFPA) is that states how close to the FSD a duct detector has to be ?

Is it 4 feet... 5 feet (minimum) ???



Thanks...

 

[rbulsara]

See NFPA 90A and/or 90B and related appedices. Also see 72. It very difficult and usually impossible to meet the criteria set in there, but you do your best. For example to be at least 6 time the diameter away from a tubulance such as discharge or a sharp bend etc.

 

[mmt019]

Look at NFPA 72, A-2-10.5.2 (1999) or NFPA 72, 5.14.4.2.1 (2002). Rbulsara is correct. The code only specifies 6X duct diameter away from bends, but it should apply for distance from supply/return fans as well. Generally, you will have stratification of smoke immediately downstream of the fan so you want to try to get away from it if possible. It is usually difficult to comply with the 6X rule, but the AHJ realizes that, so do you best.