N.Y.C. Admin. Code § MC 601: Section MC 601: General

601.1 Scope.

Duct systems used for the movement of air in air-conditioning, heating, ventilating and exhaust systems shall conform to the provisions of this chapter except as otherwise specified in Chapters 5 and 7.

Exception: Ducts discharging combustible material directly into any combustion chamber shall conform to the requirements of NFPA 82.

601.2 Air movement in corridors.

Corridors shall not be used as a portion of direct supply, return, or exhaust air system serving adjoining areas. Air transfer opening(s) shall not be permitted in walls or in doors separating public corridors from adjoining areas.

Exceptions:

1. Where located within dwelling units, the use of corridors for conveying return air shall not be prohibited.

2. Where located within tenant spaces of 1,000 square feet (93 m

2

) or less in area, the use of corridors for conveying return air is permitted.

3. Corridors in Group B office buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 of the New York City Building Code.

4. Incidental air movement from pressurized rooms within health care facilities, provided that the corridor is not the primary source of supply or return to the room.

5. Air transfer openings serving toilet rooms, bathrooms, shower rooms, sink closets, and similar auxiliary spaces opening onto the public corridor.

6. Group I-3 detention and correctional occupancies with corridor separations of open construction (e.g., grating doors or grating partitions).

7. Air transfer in openings because of pressure differential in Group I-2 health care occupancies from corridors is permitted.

8. Where door clearances do not exceed those specified for fire doors in the New York City Building Code, air transfer caused by pressure differentials shall be permitted.

9. Use of egress corridors as part of an engineered smoke control system is permitted.

601.2.1 Corridor ceiling.

Use of the space between the corridor ceiling and the floor or roof structure above as a return air plenum is permitted for one or more of the following conditions:

1. The corridor is not required to be of fire-resistance-rated construction.

2. The corridor is separated from the plenum by fire-resistance-rated construction.

3. The air-handling system serving the corridor is shut down upon activation of the air-handling unit smoke detectors required by this code.

4. The air-handling system serving the corridor is shut down upon detection of sprinkler waterflow where the building is equipped throughout with an automatic sprinkler system.

5. The space between the corridor ceiling and the floor or roof structure above the corridor is used as a component of an approved engineered smoke control system.

601.3 Exits.

Equipment and ductwork for exit enclosure ventilation shall comply with one of the following items:

1. Such equipment and ductwork shall be located exterior to the building and shall be directly connected to the exit enclosure by ductwork enclosed in construction as required by the New York City Building Code for shafts.

2. Where such equipment and ductwork is located within the exit enclosure, the intake air shall be taken directly from the outdoors and the exhaust air shall be discharged directly to the outdoors, or such air shall be conveyed through ducts enclosed in construction as required by the New York City Building Code for shafts.

3. Where located within the building, such equipment and ductwork shall be separated from the remainder of the building, including other mechanical equipment, with construction as required by the New York City Building Code for shafts.

In each case, openings into fire-resistance-rated construction shall be limited to those needed for maintenance and operation and shall be protected by self-closing fire-resistance-rated devices in accordance with the New York City Building Code for enclosure wall opening protectives. Exit enclosure ventilation systems shall be independent of other building ventilation systems.

601.4 Contamination prevention.

Exhaust ducts under positive pressure, chimneys and vents shall not extend into or pass through ducts or plenums.

Exceptions:

1. Exhaust systems conveying Class 1 or Class 2 air in accordance with ASHRAE 62.1, located in return air plenums and that have exhaust duct joints, seams and connections that comply with Section 603.9 without taking any exceptions. Such exhaust system and plenum shall be subject to special inspection in accordance with Section 1705.39 of the New York City Building Code and shall be subject to periodic inspection in accordance with Section 602.6 of this code.

2. This section shall not apply to chimneys and vents for appliances with a heat input not greater than 350,000 Btu/hr (103 kW) that pass through plenums provided that such venting systems are subject to special inspection in accordance with Section 1705.39 of the New York City Building Code and shall be subject to periodic inspection in accordance with Section 602.6 of this code and comply with one of the following requirements:

2.1. The venting system shall be listed for positive pressure applications and shall be sealed in accordance with the vent manufacturer's instructions.

2.2. The venting system shall be installed such that fittings and joints between sections are not installed in the above ceiling space.

2.3. The venting system shall be installed in a conduit or enclosure with sealed joints separating the interior of the conduit or enclosure from the ceiling space.