this is from the 2003 edition of imc, but you can with a little work look at the current edtions via this link;;;
http://publicecodes.citation.com/
sorry for the broken english, but that is how it copies::
SECTION 606
SMOKE DE TEC TION SYS TEMS CON TROL
606.1 Con trols re quired. Air dis tribution sys tems shall be
equipped with smoke de tectors listed and la beled for in stallation
in air dis tribution sys tems, as re quired by this sec tion.
606.2 Where re quired. Smoke de tec tors shall be in stalled
where in dicated in Sec tions 606.2.1 through 606.2.3.
Exception: Smoke de tectors shall not be re quired where air
distribution sys tems are in ca pa ble of spread ing smoke beyond
the en clos ing walls, floors and ceil ings of the room or
space in which the smoke is gen erated.
606.2.1 Re turn air sys tems. Smoke de tectors shall be in -
stalled in re turn air sys tems with a de sign ca pacity greater
than 2,000 cfm (0.9 m3/s), in the re turn air duct or ple num
upstream of any fil ters, ex haust air con nec tions, out door air
connections, or de con tam i na tion equip ment and ap pli ances.
Exception: Smoke de tectors are not re quired in the re turn
air sys tem where all por tions of the build ing served by the
air dis tribution sys tem are pro tected by area smoke de tectors
con nected to a fire alarm sys tem in ac cordance with the
International Fire Code. The area smoke de tection sys tem
shall com ply with Sec tion 606.4.
606.2.2 Com mon sup ply and re turn air sys tems. Where
mul ti ple air-handling sys tems share com mon sup ply or return air ducts or ple nums with a com bined de sign ca pac ity
greater than 2,000 cfm (0.9 m3/s), the re turn air sys tem shall
be pro vided with smoke de tectors in ac cor dance with Sec -
tion 606.2.1.
Ex cep tion: In dividual smoke de tectors shall not be required
for each fan-powered ter mi nal unit, pro vided that
such units do not have an in dividual de sign ca pac ity
greater than 2,000 cfm (0.9 m3/s) and will be shut down by
activation of one of the fol lowing:
1. Smoke de tectors re quired by Sec tions 606.2.1 and
606.2.3.
2. An ap proved area smoke de tector sys tem lo cated in the
re turn air ple num serv ing such units.
3. An area smoke de tec tor sys tem as pre scribed in the exception
to Sec tion 606.2.1.
In all cases, the smoke de tec tors shall com ply with Sec -
tions 606.4 and 606.4.1.
606.2.3 Re turn air ris ers. Where re turn air ris ers serve two or
more sto ries and serve any por tion of a re turn air sys tem hav ing
a de sign ca pacity greater than 15,000 cfm (7.1 m3/s), smoke
detectors shall be in stalled at each story. Such smoke de tectors
shall be lo cated up stream of the con nection be tween the re turn
air riser and any air ducts or ple nums.
606.3 In stal la tion. Smoke de tectors re quired by this sec tion
shall be in stalled in ac cordance with NFPA 72. The re quired
smoke de tec tors shall be in stalled to mon i tor the en tire air flow
conveyed by the sys tem in clud ing re turn air and ex haust or re -
lief air. Ac cess shall be pro vided to smoke de tectors for in spection
and main te nance.
606.4 Con trols op er a tion. Upon ac tivation, the smoke de tectors
shall shut down the air dis tribution sys tem. Air dis tribution
sys tems that are part of a smoke con trol sys tem shall switch to
the smoke con trol mode upon ac tivation of a de tec tor.
606.4.1 Su pervision. The duct smoke de tectors shall be con -
nected to a fire alarm sys tem. The ac tuation of a duct smoke
detector shall ac tivate a vis ible and au dible su pervisory sig nal
at a con stantly at tended lo cation.
Exceptions:
1. The su pervisory sig nal at a con stantly at tended lo cation
is not re quired where the duct smoke de tec tor ac tivates
the build ing’s alarm-indicating ap pli ances.
2. In oc cu pan cies not re quired to be equipped with a fire
alarm sys tem, ac tu a tion of a smoke de tec tor shall ac tivate
a vis i ble and an au di ble sig nal in an ap proved lo -
ca tion. Duct smoke de tec tor trou ble con di tions shall
activate a vis ible or au di ble sig nal in an ap proved lo cation
and shall be iden tified as air duct de tec tor trou ble.