Page 52 - 2018_IMC

VENTILATION

flow rate over the 4-hour period shall be not less tioning systems that supply required ventilation air shall be
than that prescribed by Equation 4-9. provided with controls designed to automatically maintain
403.3.2.2 Outdoor air for other spaces. Corridors and the required outdoor air supply rate during occupancy.
other common areas within the conditioned space shall
be provided with outdoor air at a rate of not less than SECTION 406
0.06 cfm per square foot of floor area.
VENTILATION OF UNINHABITED SPACES
403.3.2.3 Local exhaust. Local exhaust systems shall
be provided in kitchens, bathrooms and toilet rooms 406.1 General. Uninhabited spaces, such as crawl spaces and
and shall have the capacity to exhaust the minimum air- attics, shall be provided with natural ventilation openings as
flow rate determined in accordance with Table required by the International Building Code or shall be pro-
403.3.2.3. vided with a mechanical exhaust and supply air system. The
mechanical exhaust rate shall be not less than 0.02 cfm per
TABLE 403.3.2.3 3 2
MINIMUM REQUIRED LOCAL EXHAUST RATES square foot (0.00001 m /s • m m ) of horizontal area and shall be
FOR GROUP R-2, R-3, AND R-4 OCCUPANCIES automatically controlled to operate when the relative humid-
AREA TO BE EXHAUSTED EXHAUST RATE CAPACITY ity in the space served exceeds 60 percent.
100 cfm intermittent or
Kitchens
25 cfm continuous
SECTION 407
50 cfm intermittent or AMBULATORY CARE FACILITIES AND
Bathrooms and toilet rooms
20 cfm continuous GROUP I-2 OCCUPANCIES
3
For SI: 1 cubic foot per minute = 0.0004719 m /s. 407.1 General. Mechanical ventilation for ambulatory care
403.3.2.4 System controls. Where provided within a facilities and Group I-2 occupancies shall be designed and
dwelling unit, controls for outdoor air ventilation sys- installed in accordance with this code and ASHRAE 170.
tems shall include text or a symbol indicating the sys-
tem’s function.
403.3.2.5 Ventilating equipment. Exhaust equipment
serving single dwelling units shall be listed and labeled
to provide the minimum required air flow in accor-
dance with ANSI/AMCA 210-ANSI/ASHRAE 51.

SECTION 404
ENCLOSED PARKING GARAGES
404.1 Enclosed parking garages. Mechanical ventilation
systems for enclosed parking garages shall operate continu-
ously or shall be automatically operated by means of carbon
monoxide detectors applied in conjunction with nitrogen
dioxide detectors. Such detectors shall be listed in accordance
with UL 2075 and installed in accordance with their listing
and the manufacturers’ instructions. Automatic operation
shall cycle the ventilation system between the following two
modes of operation:
1. Full-on at an airflow rate of not less than 0.75 cfm per
2
3
square foot [0.0038 m /(s • m )] of the floor area served.
2. Standby at an airflow rate of not less than 0.05 cfm per
3
2
square foot [0.00025 m /(s • m )] of the floor area served.

404.2 Occupied spaces accessory to public garages. Con-
necting offices, waiting rooms, ticket booths and similar uses
that are accessory to a public garage shall be maintained at a
positive pressure and shall be provided with ventilation in
accordance with Section 403.3.1.
SECTION 405
SYSTEMS CONTROL
405.1 General. Mechanical ventilation systems shall be pro-
vided with manual or automatic controls that will operate
such systems whenever the spaces are occupied. Air-condi-

2018 INTERNATIONAL MECHANICAL CODE  35
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