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Scott35 Online Happy OP
Broom Pusher and
Hello everyone,

I am Designing a 55,000 Ft² Project, which has 1 Hour Rated Corridors with AC Ducts.

It has been a while for me, and I cannot remember the following:


[*] Is the minimum distance between the Duct, and the Smoke Detector, 36"?

[*] Are these dimensions from the Centerlines of the Detector and the Duct, or the edge of the Duct closest to the detector, to the edge of the detector closest to the duct?

[*] Detectors + Dampers for Return Air Ducts only, or is there a need for dampers + detectors on supply and return ducts?

[*] Interlocking of Smoke Detectors was an optional thing in many of the past projects, but this current project is a place of assembly - would I need to Interlock the Detectors controlling the damper motors?

[*] If #4 above is "Yes" - regarding Interlocks, would there be a requirement for HVAC shutdown &/or interfacing with the FACP?

The Project is not a Multifloor / Highrise building (30' tall Concrete Tilt-Up), but it will be a place of assembly.

Smoke Detectors will control Duct Dampers, which are Spring Wound Closing, held in open position via Electric Motor.

One Smoke Detector per Duct Damper.

The Electric Motor will be energized in normal operation, via Normally Closed contact in the Smoke Detector, therefore keeping the Damper open.

If Detector goes into Emergency Mode (Smoke is detected), the N.C. contact is latched open, and the Damper Motor is de-energized - allowing the Damper to Spring Wind its self closed.
Detector remains in this state (with audible alarm options), until manually reset.

Any information would be great!


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
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Ron Offline
What version of a mechanical code is followed in the jurisdiction? IMC or NFPA 90? Answers differ depending on the code in place.

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Scott35 Online Happy OP
Broom Pusher and
As far as I know, these are the following relavent Codes:

Mechanical Code - Local + Model:

2001 CMC (California Mechanical Code) - Title 24, Part 4.

Model Code for 2001 CMC: 2000 UMC (IAPMO).

Building Code - Local + Model:

2001 CBC (California Building Code) - Title 24, Part 2.

Model Code for 2001 CBC: 1997 UBC (ICBO)

Fire Code - Local + Model:

2001 CFC (California Fire Code) - Title 24, Part 9.

Model Code for 2001 CFC: 2000 UFC (WFCA).

Hope something in this list is helpful!

Thanks for the reply!


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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