Page 58 - 2018_IMC

CHAPTER 5

EXHAUST SYSTEMS

User note:
About this chapter: Chapter 5 addresses exhaust systems for, among others, kitchens, laboratories, processes, garages, hazardous sys-
®
tems, clothes dryers and smoke control systems. Many provisions are linked to the International Fire Code . Exhaust systems mitigate health
and fire hazards by removing and diluting contaminants in buildings. Exhaust system discharge location is also addressed as an important
concern.

SECTION 501 lines; 10 feet (3048 mm) from operable openings
GENERAL into buildings; 6 feet (1829 mm) from exterior walls
501.1 Scope. This chapter shall govern the design, construc- and roofs; 30 feet (9144 mm) from combustible
tion and installation of mechanical exhaust systems, includ- walls and operable openings into buildings that are
ing exhaust systems serving clothes dryers and cooking in the direction of the exhaust discharge; 10 feet
appliances; hazardous exhaust systems; dust, stock and refuse (3048 mm) above adjoining grade.
conveyor systems; subslab soil exhaust systems; smoke con- 2. For other product-conveying outlets: 10 feet (3048
trol systems; energy recovery ventilation systems and other mm) from the property lines; 3 feet (914 mm) from
systems specified in Section 502. exterior walls and roofs; 10 feet (3048 mm) from
501.2 Independent system required. Single or combined operable openings into buildings; 10 feet (3048 mm)
mechanical exhaust systems for environmental air shall be above adjoining grade.
independent of all other exhaust systems. Dryer exhaust shall 3. For all environmental air exhaust: 3 feet (914 mm)
be independent of all other systems. Type I exhaust systems from property lines; 3 feet (914 mm) from operable
shall be independent of all other exhaust systems except as openings into buildings for all occupancies other
provided in Section 506.3.5. Single or combined Type II than Group U, and 10 feet (3048 mm) from mechan-
exhaust systems for food-processing operations shall be inde- ical air intakes. Such exhaust shall not be considered
pendent of all other exhaust systems. Kitchen exhaust sys- hazardous or noxious.
tems shall be constructed in accordance with Section 505 for
domestic cooking operations and Sections 506 through 509 4. Exhaust outlets serving structures in flood hazard
for commercial cooking operations. areas shall be installed at or above the elevation
required by Section 1612 of the International Build-
501.3 Exhaust discharge. The air removed by every ing Code for utilities and attendant equipment.
mechanical exhaust system shall be discharged outdoors at a
point where it will not cause a public nuisance and not less 5. For specific systems, see the following sections:
than the distances specified in Section 501.3.1. The air shall 5.1. Clothes dryer exhaust, Section 504.4.
be discharged to a location from which it cannot again be 5.2. Kitchen hoods and other kitchen exhaust
readily drawn in by a ventilating system. Air shall not be
exhausted into an attic, crawl space, or be directed onto walk- equipment, Sections 506.3.13, 506.4 and
ways. 506.5.
Exceptions: 5.3. Dust, stock and refuse conveying systems,
Section 511.2.
1. Whole-house ventilation-type attic fans shall be per-
mitted to discharge into the attic space of dwelling 5.4. Subslab soil exhaust systems, Section 512.4.
units having private attics. 5.5. Smoke control systems, Section 513.10.3.
2. Commercial cooking recirculating systems. 5.6. Refrigerant discharge, Section 1105.7.
3. Where installed in accordance with the manufac- 5.7. Machinery room discharge, Section
turer’s instructions and where mechanical or natural 1105.6.1.
ventilation is otherwise provided in accordance with
Chapter 4, listed and labeled domestic ductless 501.3.2 Exhaust opening protection. Exhaust openings
range hoods shall not be required to discharge to the that terminate outdoors shall be protected with corrosion-
outdoors. resistant screens, louvers or grilles. Openings in screens,
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louvers and grilles shall be sized not less than / inch (6.4
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501.3.1 Location of exhaust outlets. The termination mm) and not larger than / inch (12.7 mm). Openings
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point of exhaust outlets and ducts discharging to the out- shall be protected against local weather conditions. Lou-
doors shall be located with the following minimum dis- vers that protect exhaust openings in structures located in
tances: hurricane-prone regions, as defined in the International
1. For ducts conveying explosive or flammable vapors, Building Code, shall comply with AMCA Standard 550.
fumes or dusts: 30 feet (9144 mm) from property Outdoor openings located in exterior walls shall meet the
2018 INTERNATIONAL MECHANICAL CODE  41
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