Smoke detector
Smoke detector
(OP)
Per "1997 Standard Mechanical Code", recirculating air system with a fan capacity great than 2000 cfm shall automatically shut down by means of an approved smoke detector placed in the return air stream. Could anyone explain to me why only return air stream, not discharge air stream also? How to detect the smoke in the discharge side?
How to detect the spark of the motor in a blow-through air-handling unit?
Thanks in advance!
How to detect the spark of the motor in a blow-through air-handling unit?
Thanks in advance!





RE: Smoke detector
If there are filters in the system, the discharge stream may not have sufficient particulate matter to trigger the smoke detector.
TTFN
RE: Smoke detector
RE: Smoke detector
However, NFPA-90A (2002), if followed in your area, still requires that that a duct smoke be placed "downstream of the air filters and ahead of any branch connections in air supply systems having a capacity greater than 944 L/sec (2000 ft3/min)."
I would do both to be safe. The supply smoke protects you if the supply motor, belt, or bearing smokes itself...
RE: Smoke detector
RE: Smoke detector
RE: Smoke detector
But what is the best way to install the smoke detector in the discharge side of the fan so it can hold 50" static pressure?
RE: Smoke detector
http://www.hochiki.com/literature/installation/ha-06-073.pdf
RE: Smoke detector