Exhaust Systems

Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:

• CMC § 1.4. High relevance — show source text

  1.4. The penetrations are in parking garage exhaust or supply shafts that are separated from other building shafts by not less than 2-hour fire-resistance-rated construction. 2. In Group B and R occupancies equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, smoke dampers are not required at penetrations of shafts where all of the following criteria are met: 2.1. Kitchen, clothes dryer, bathroom and toilet room exhaust openings are installed with steel exhaust subducts, having a wall thickness of not less than 0.0187 inch (0.4712 mm). 2.2. The subducts extend not less than 22 inches (559 mm) vertically. 2.3. An exhaust fan is installed at the upper terminus of the shaft that is powered continuously in accordance with the provisions of Section 909.11, so as to maintain a continuous upward airflow to the outdoors. 3. Smoke dampers are not required at penetration of exhaust or supply shafts in parking garages that are separated from other building shafts by not less than 2-hour fire-resistance-rated construction. 4. Smoke dampers are not required at penetrations of shafts where ducts are used as part of an approved mechanical smoke control system designed in accordance with Section 909 and where the smoke damper will interfere with the operation of the smoke control system. 5. Fire dampers and combination fire/smoke dampers are not required in kitchen and clothes dryer exhaust systems where dampers are prohibited by the California Mechanical Code .

  717.5.3.1 Continuous upward airflow. Fire dampers and smoke dampers shall not be installed in shafts that are required to maintain a continuous upward airflow path where closure of the damper would result in the loss of the airflow.

  717.5.4 Fire partitions. In other than Group A, E, I and R occupancies, high-rise buildings, and other applications listed in Section 1.11 regulated by the Office of the State Fire Marshal, ducts and air transfer openings that penetrate fire partitions shall be protected with listed fire dampers installed in accordance with their listing.

  Exceptions: In occupancies other than Group H and L, fire dampers are not required where any of the following apply:

  1. Corridor walls in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 and the duct is protected as a through penetration in accordance with Section 714.
  2. Tenant partitions in covered and open mall buildings where the walls are not required by provisions elsewhere in the code to extend to the underside of the floor or roof sheathing, slab or deck above.
  3. The duct system is constructed of approved materials in accordance with the California Mechanical Code and the duct penetrating the wall complies with all of the following requirements: 3.1. The duct shall not exceed 100 square inches (0.06 m [2] ). 3.2. The duct shall be constructed of steel not less than 0.0217 inch (0.55 mm) in thickness.

  3.3. The duct shall not have openings that communicate the corridor with adjacent spaces or rooms. 3.4. The duct shall be installed above a ceiling. 3.5. The duct shall not terminate at a wall register in the fire-resistance-rated wall. 3.6. A minimum 12-inch-long (305 mm) by 0.060-inch-thick (1.52 mm) steel sleeve shall be centered in each duct opening.

• CMC § 510.9. Medium relevance — show source text

  Exception: Type I Hood exhaust termination shall be in accordance with Section 510.9.

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  tem in accordance with Section 505.7.3 do not require design as Class 1 product-conveying ducts.

  Exceptions:

  (1) Ductless range hoods where installed in accordance with the manufacturer’s installation instructions.

  (2) Condensing clothes dryers where installed in accordance with the manufacturer’s installation instructions.

  504.1.1 Backdraft Protection. Exhaust ducts shall terminate outside the building and shall be equipped with backdraft dampers or with motorized dampers that automatically shut where the systems or spaces served are not in use. [OSHPD 1, 1R, 2, 4 & 5] Exception: Back- draft dampers are not required when the exhaust fan must operate continuously.

  Exception: Where the exhaust duct does not discharge into a common exhaust plenum and one of the following:

  (1) The exhaust fan runs continuously.

  (2) The exhaust duct serves space(s) that are not mechanically heated or cooled.

  (3) The space served is maintained at positive pressure. 504.2 Independent Exhaust Systems. Single or combined mechanical exhaust systems for environmental air shall be independent of other exhaust systems. Combined exhaust systems shall operate at negative pressure and shall terminate in accordance with Section 502.2.1. Clothes dryer exhaust systems shall be independent of all other exhaust systems except where permitted in Section 504.4.4. 504.3 Domestic Cooking Exhaust Equipment. Domestic cooking exhaust equipment shall comply with the following requirements, as applicable:

  (1) The fan for overhead range hoods and downdraft exhaust equipment not integral with the cooking appliance shall comply with UL 507.

  (2) Overhead range hoods and downdraft exhaust equipment with integral fans shall comply with UL 507.

  (3) Domestic cooking appliances with integral downdraft exhaust equipment shall comply with UL 858 or CSA/ANSI Z21.1/CSA 1.1.

  (4) Microwave ovens with integral exhaust for installation over the cooking surface shall comply with UL 923.

  (5) All domestic kitchen exhaust ducts used in conjunction with domestic range or cooktop hoods shall be constructed of metal and shall have smooth interior surfaces, fastened and sealed with duct mastic or metal tapes that meet the requirements of UL 181A.

  Exception: Ducts for domestic kitchen downdraft grillrange ventilation installed under a concrete slab floor shall be permitted to be of approved Schedule 40 PVC provided the following conditions are met:

  (1) The under-floor trench in which the duct is installed shall be completely backfilled with sand or gravel.

  (2) Not more than 1 inch (25.4 mm) of 6 inch diameter (150 mm) PVC coupling shall be permitted to protrude above the concrete floor surface.

  (3) PVC pipe joints shall be solvent cemented to provide an air and greasetight duct.

  (4) The duct shall terminate above grade outside the building and shall be equipped with a backdraft damper.

  (6) Range hoods shall discharge to the outdoors through a single wall duct and shall not terminate in an attic or crawl space.

• California Mechanical Code Medium relevance — show source text

  A mechanical code, as with any other code, is intended to be adopted as a legally enforceable document to safeguard health, safety, property, and public welfare. The code cannot be effective without satisfactory provisions for its administration and enforcement. The Authority Having Jurisdiction is to review the proposed and completed work and decide whether a mechanical system conforms to the code requirements. As a public servant, the Authority Having Jurisdiction enforces the code in an unbiased proper manner. The design professional is responsible for the design of a safe mechanical system. The contractor is responsible for installing the system in accordance with the plans.

  Chapter 2 Definitions. To maintain consistency and encourage the use of common terminology, Chapter 2 establishes definitions to provide clarity of terms and promote the use of a common language throughout the code. Understanding definitions within the context of their application enables greater collaboration, efficiency, standardization, and interpretation in applying and enforcing terms used throughout the code. Codes are technical documents, and every term can impact the meaning of the code text. Terms not defined have a normally accepted meaning.

  Chapter 3 General Regulations. Chapter 3 regulates the general requirements, not specific to other chapters, for installing mechanical systems. Many regulations are not specific mechanical requirements but relate to the overall mechanical system. This chapter contains safety requirements for appliance location and installation, appliance and system access, condensate disposal, clearances to combustibles, and return or outside air used in mechanical systems. Listing method of approval, based on applicable nationally recognized standards for the safe and proper installation of mechanical systems, is essential to ensure protection of public health, safety, and welfare. These safety requirements provide protection for piping, tubing, materials, and structures, including provisions for installation practices addressing stress and strain, sleeving, and hanger support. The building’s structural stability is protected by the regulations for cutting and notching of structural members.

  Chapter 4 Ventilation Air. Chapter 4 regulates the minimum requirements for ventilation air supply, exhaust, and makeup air for occupiable spaces within a building. Building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. Ventilation air may be composed of mechanical or natural ventilation, infiltration, recirculated air, transfer air, or a suitable combination of these. Providing a comfortable and healthy indoor environment for building occupants is of primary concern. When determining ventilation rates, typical and unusual significant sources of indoor pollution need to be controlled. Areas such as kitchens, bathrooms, and laundries are all built to allow specific functions. These spaces produce pollutants such as moisture, odors, volatile organic compounds, particles, or combustion byproducts. The purpose of local exhaust is to control concentrates of these pollutants in the room into which they were emitted and to reduce the spread of pollutants into other parts of the occupancy. Local exhaust ventilation is the source control for pollution that is expected in certain rooms. Using local exhaust to extract contaminants before they mix with the indoor environment is essential.

  Chapter 5 Exhaust Systems. Chapter 5 regulates the minimum requirements for exhaust systems. Chapter 5 contains two parts: Part I provides exhaust requirements for environmental air ducts and product conveying systems; Part II provides exhaust requirements for commercial hoods and kitchen ventilation. Environmental air ducts include exhaust ducts used for transporting the air from domestic kitchens, bathrooms, shower rooms, lo

• CMC § 519.4 Medium relevance — show source text

  519.4 Type II Exhaust Duct Systems. Ducts and plenums serving Type II hoods shall be constructed of rigid metallic materials in accordance with Chapter 6. Duct bracing and supports shall comply with Chapter 6. Ducts subject to positive pressure shall be adequately sealed.

  519.5 Termination of Type II Hood Exhaust System. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away

  «

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  EXHAUST SYSTEMS

  from roof surfaces within 40 inches (1016 mm). The discharge outlet of moisture conveying exhaust ducts, such as dishwasher exhaust ducts, shall not terminate over a public way or over an area where condensate or vapor could create a nuisance or hazard.

  519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.

  519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems.

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  CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

  CHAPTER 6 – DUCT SYSTEMS

  (Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

  Adopting Agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  Adopting Agency	BSC	BSC- CG	SFM	1	2	1-AC	AC	** SS**	** SS/CC**	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
  Adopt Entire Chapter	X							X								X
  Adopt Entire Chapter as amended (amended sections listed below)			X	X	X					X	X	X	X	X	X
  Adopt only those sections that are listed below																					X
  Chapter/Section
  _601.2.

• CMC § 504.4 Medium relevance — show source text

  (6) Range hoods shall discharge to the outdoors through a single wall duct and shall not terminate in an attic or crawl space.

  504.4 Clothes Dryers. A clothes dryer exhaust duct shall not be connected to a vent connector, gas vent, chimney, and shall not terminate into a crawl space, attic, or other concealed space. Exhaust ducts shall not be assembled with screws or other fastening means that extend into the duct and that are capable of catching lint, and that reduce the efficiency of the exhaust system. Exhaust ducts shall be constructed of rigid metallic material. Transition ducts used to connect the dryer to the exhaust duct shall be listed and labeled in accordance

  with UL 2158A, or installed in accordance with the clothes dryer manufacturer’s installation instructions. Clothes dryer exhaust ducts shall terminate to the outside of the building in accordance with Section 502.2.1 and shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination. Devices, such as fire or smoke dampers that will obstruct the flow of the exhaust shall not be used. Where joining of ducts, the male end shall be inserted in the direction of airflow.

  504.4.1 Provisions for Makeup Air. Makeup air shall be provided in accordance with the following:

  (1) Makeup air shall be provided for Type 1 clothes dryers in accordance with the manufacturer’s installa tion instructions. [NFPA 54:10.4.4.1] Where a closet is designed for the installation of a clothes dryer, an opening of not less than 100 square inches (0.065 m [2] ) for makeup air shall be provided in the door or by other approved means.

  (2) Provision for makeup air shall be provided for Type 2 clothes dryers, with a minimum free area of 1 square inch (0.0006 m [2] ) for each 1000 British thermal units per hour (Btu/h) (0.293 kW) total input rating of the dryer(s) installed. [NFPA 54:10.4.4.2]

  504.4.2 Domestic Clothes Dryers. Where a compartment or space for a Type 1 clothes dryer is provided, not less than a 4 inch diameter (102 mm) exhaust duct of approved material shall be installed in accordance with Section 504.0.

  Type 1 clothes dryer exhaust ducts shall be of rigid metal and shall have smooth interior surfaces. The diam eter shall be not less than 4 inches nominal (100 mm), and the thickness shall be not less than 0.016 of an inch

  (0.406 mm).

  504.4.2.1 Length Limitation. Unless otherwise permitted or required by the dryer manufacturer’s instructions and approved by the Authority Having Jurisdiction, domestic dryer moisture exhaust ducts

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  shall not exceed a total combined horizontal and ver tical length of 14 feet (4267 mm), including two 90 degree (1.57 rad) elbows. A length of 2 feet (610 mm) shall be deducted for each 90 degree (1.57 rad) elbow in excess of two.

• CMC § 0.0006 Medium relevance — show source text

  (2) Provision for makeup air shall be provided for Type 2 clothes dryers, with a minimum free area of 1 square inch (0.0006 m [2] ) for each 1000 British thermal units per hour (Btu/h) (0.293 kW) total input rating of the dryer(s) installed. [NFPA 54:10.4.4.2]

  504.4.2 Domestic Clothes Dryers. Where a compartment or space for a Type 1 clothes dryer is provided, not less than a 4 inch diameter (102 mm) exhaust duct of approved material shall be installed in accordance with Section 504.0.

  Type 1 clothes dryer exhaust ducts shall be of rigid metal and shall have smooth interior surfaces. The diam eter shall be not less than 4 inches nominal (100 mm), and the thickness shall be not less than 0.016 of an inch

  (0.406 mm).

  504.4.2.1 Length Limitation. Unless otherwise permitted or required by the dryer manufacturer’s instructions and approved by the Authority Having Jurisdiction, domestic dryer moisture exhaust ducts

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  shall not exceed a total combined horizontal and ver tical length of 14 feet (4267 mm), including two 90 degree (1.57 rad) elbows. A length of 2 feet (610 mm) shall be deducted for each 90 degree (1.57 rad) elbow in excess of two.

  Exception: Where an exhaust duct power ventilator, in accordance with Section 504.4.2.3, is used, the maximum length of the dryer exhaust duct shall be permitted to be in accordance with the dryer exhaust duct power ventilator manufacturer’s installation instructions.

  504.4.2.2 Transition Ducts. Listed clothes dryer transition ducts not more than 6 feet (1829 mm) in length shall be permitted to be used to connect the Type 1 dryer to the exhaust ducts. Transition ducts and flexible clothes dryer transition ducts shall not be concealed within construction, and shall be installed in accordance with the manufacturer’s

  installation instructions.

  504.4.2.3 Exhaust Duct Power Ventilators.

  Dryer exhaust duct power ventilators for single residential clothes dryers shall be listed and labeled in accordance with UL 705 and installed in accor dance with the manufacturer’s installation instruc tions.

  504.4.3 Commercial Clothes Dryers. Commercial dryer exhaust ducts shall be installed in accordance with their listings. The installation of commercial clothes dryer exhaust ducts shall comply with the appliance manufacturer’s installation instructions.

  504.4.3.1 Exhaust Ducts for Type 2 Clothes Dryers. Exhaust ducts for Type 2 clothes dryers shall comply with the following:

  (1) Exhaust ducts for Type 2 clothes dryers shall comply with Section 504.4. [NFPA 54:10.4.6.1]

• CMC § 62.1. Medium relevance — show source text

  (3) The mechanical exhaust flow minus the available transfer air from conditioned spaces or return air plenums on the same floor, not in different smoke or fire compartments, and that at their closest point are within 15 feet (4572 mm) of each other. Available transfer air is that portion of outdoor ventilation air that:

  (a) is not required to satisfy other exhaust needs,

  (b) is not required to maintain pressurization of other spaces, and

  (c) is transferable according to applicable codes and standards and to the class of air recirculation limitations in Chapter 4 or ASHRAE 62.1.

  Exceptions: (1) Biosafety level classified laboratories 3 or higher. (2) Vivarium spaces. (3) Spaces that are required by applicable codes and standards to be maintained at positive pressure relative to adjacent spaces. For spaces taking this exception, any transferable air that is not directly transferred shall be made available to the associated air-handling unit and shall be used whenever economizer or other options do not save more energy. (4) Spaces where the demand for transfer air may exceed the available transfer airflow rate and where the spaces have a required negative pressure relationship. For spaces taking this exception, any transferable air that is not directly transferred shall be made available to the associated air-handling unit and shall be used whenever economizer or other options do not save more energy. [ASHRAE 90.1:6.5.7.1] E 503.5.11.2 Kitchen Exhaust Systems. Replacement air introduced directly into the hood cavity of kitchen exhaust hoods shall not exceed 10 percent of the hood exhaust airflow rate. [ASHRAE 90.1:6.5.7.2.1]

  E 503.5.11.2.1 Exhaust Flow Rate. Where a kitchen or dining facility has a total kitchen hood exhaust airflow rate exceeding 5000 ft [3] /min (2.3597 m [3] /s), each hood shall have an exhaust rate in accordance with Table E 503.5.11.2.1.

  Where a single hood, or hood section, is installed over appliances with different duty ratings, the maximum allowable flow rate for the hood or

  hood section shall not exceed the values in Table E 503.5.11.2.1 for the highest appliance duty rating under the hood or hood section. Refer to ASHRAE 154 for definitions of hood type, appliance duty, and net exhaust flow rate. Exception: Seventy-five percent or more of the total replacement air is transfer air that would otherwise be exhausted. [ASHRAE 90.1:6.5.7.2.2] E 503.5.11.2.2 Kitchen or Dining Facility. Where a kitchen or dining facility has a total kitchen hood exhaust airflow rate more than 5000 ft [3] /min (2.3597 m [3] /s), then one of the following shall be provided:

  (1) Fifty percent or more of all replacement air is transfer air that would otherwise be

  exhausted.

  (2) Demand ventilation systems on 75 percent or more of the exhaust air. Such systems shall be capable of and configured to provide 50 percent or more reduction in exhaust and replacement air system airflow rates, including controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent, and combustion products during cooking and idle.

• CMC § 2025 Medium relevance — show source text

  The building’s structural stability is protected by the regulations for cutting and notching of structural members.

  Chapter 4 Ventilation Air. Chapter 4 regulates the minimum requirements for ventilation air supply, exhaust, and makeup air for occupiable spaces within a building. Building ventilation is one important factor affecting the relationship between airborne transmission of respiratory infections and the health and productivity of workers. Ventilation air may be composed of mechanical or natural ventilation, infiltration, recirculated air, transfer air, or a suitable combination of these. Providing a comfortable and healthy indoor environment for building occupants is of primary concern. When determining ventilation rates, typical and unusual significant sources of indoor pollution need to be controlled. Areas such as kitchens, bathrooms, and laundries are all built to allow specific functions. These spaces produce pollutants such as moisture, odors, volatile organic compounds, particles, or combustion byproducts. The purpose of local exhaust is to control concentrates of these pollutants in the room into which they were emitted and to reduce the spread of pollutants into other parts of the occupancy. Local exhaust ventilation is the source control for pollution that is expected in certain rooms. Using local exhaust to extract contaminants before they mix with the indoor environment is essential.

  Chapter 5 Exhaust Systems. Chapter 5 regulates the minimum requirements for exhaust systems. Chapter 5 contains two parts: Part I provides exhaust requirements for environmental air ducts and product conveying systems; Part II provides exhaust requirements for commercial hoods and kitchen ventilation. Environmental air ducts include exhaust ducts used for transporting the air from domestic kitchens, bathrooms, shower rooms, locker rooms, janitor’s closets, and clothes dryers. Systems that carry nonabrasive exhaust, such as smoke, moderate abrasives such as sawdust, and high abrasives such as manganese or acid vapors use product-conveying ducts. Part II provides the minimum fire safety requirements related to the design, installation, inspection, and maintenance of grease-type operations, such as cooking, for both fuel-gas and solid fuel. Cooking produces a significant amount of smoke, fumes, vapors, heat, and other pollutants. Therefore, acceptable kitchen ventilation is necessary to prevent fires from the build-up of grease and to provide the occupants protection from smoke, unpleasant odors, pollutants, and dangerous gases. There are two types of exhaust hoods (Type I and Type II) used in commercial kitchen applications.

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  FORMAT OF THE UNIFORM MECHANICAL CODE

  Type I hoods are intended to be installed above equipment or appliances that generate grease or smoke. Type II hoods are intended to be installed above equipment or appliances that generate steam, vapor, heat, or odors and do not generate grease or smoke.

  Chapter 6 Duct Systems. Chapter 6 regulates requirements for ducts and plenums that are portions of a heating, cooling, ventilation, or exhaust system. This chapter contains material and installation requirements for metal, gypsum, factory-made, flexible, and plastic ducts. It also contains provisions for duct insulation, dampers, fire protection, and automatic shutoff for the building’s air distribution system. It is worth noting that exhaust ducts are regulated by Chapter 5, and combustion air ducts are regulated by Chapter 7.

• CMC § 1119.1 Medium relevance — show source text

  EVAPORATIVE

  Condenser . . . . . . . . . . . . . . . . . 1119.1, 1120.1, 1123.1

  Cooler. . . . . . . . . . . . . . . . . . . . . . 207.0, 932.3, E 403.2

  Cooler, portable, definition . . . . . . . . . . . . . . . . . . 218.0

  Cooling system . . . . . . . . . . . . . . . . 207.0, 406.0, 932.0

  EVAPORATOR

  Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207.0

  EXCESS FLOW VALVE . . . . . . . . . . . . . . . . . . . . . . . . 207.0,

  1309.0, 1406.2.1.5

  EXHAUST

  Bathroom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3

  Clothes dryer . . . . . . . . . . . . . . 504.4, 504.4.2–504.4.5

  Commercial kitchen. . . . . . . . . . . . . . Chapter 5 (Part II)

  Discharge, type I

  and type II system . . . . . . . . . . . . . . . . . 519.5, 510.9,

  Ducts . . . . . . . . . . . . . . . . . . . . . . . 504.0, 506.0, 510.0,

  Chapter 6, 1106.8

  Independent system . . . . . . . . . . . . . . . . 504.2, 517.3.1

  Kitchen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.4

  Mechanical . . . . . . . . . . . . . . . . . . . 405.3, 405.4, 403.7,

  Chapter 5, 1105.5.2,

  1106.0, Table 403.7

  Product conveying. . . . . . . . . . . . . . 218.0, 505.0, 506.0

  Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . 403.7.1, 405.3.1,

  405.4.1, E 503.5.11.2.1,

  E 503.5.11.3, Table 403.7

  Refrigeration

  machinery room . . . . . . . . . . . . . . . . 1105.5.2, 1106.0

  Separation from

  other exhaust . . . . . . . . . . . . . . . . . . . . 504.2, 517.3.1

  Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.1

• CMC § 503.4.6.4.1 Medium relevance — show source text

  E 503.4.6.4.1 Shutoff Damper Controls. Outdoor air intake and exhaust systems shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use. Outdoor air and exhaust or relief dampers shall be capable of and configured to automatically shut off during preoccupancy building warm-up, cooldown, and setback, except when the supply of outdoor air reduces energy costs or when outdoor air shall

  be supplied to comply with the code require ments.

  Exceptions:

  (1) Nonmotorized (gravity back draft) dampers shall be permitted for exhaust and relief in buildings less than three stories in height and for outdoor air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 0, 1, 2 and 3. Nonmotorized dampers for outdoor air intakes shall be protected from direct exposure to wind.

  (2) Nonmotorized dampers shall be permitted in systems with a design outdoor air intake or exhaust capacity of 300 ft [3] /min (0.142 m [3] /s) or less.

  (3) Dampers shall not be required in ventilation or exhaust systems serving unconditioned spaces.

  (4) Dampers shall not be required in exhaust systems serving Type 1 kitchen exhaust hoods.

  (5) Dampers are not required in systems intended to operate continuously. [ASHRAE 90.1:6.4.3.4.2]

  E 503.4.6.4.2 Dampers Leakage. Where outdoor air supply, and exhaust or relief dampers are required in Section E 503.4.6.4, they shall have a maximum leakage rate in accordance with Table E 503.4.6.4.2. [ASHRAE 90.1:6.4.3.4.3]

  E 503.4.6.4.3 Ventilation Fan Controls. Fans with motors more than 0.75 hp (0.56 kW) shall have automatic controls in accordance with Section E 503.4.6.3.1 that are capable of and configured to shut off fans when not required.

  Exception: HVAC systems intended to operate continuously. [ASHRAE 90.1:6.4.3.4.4]

  E 503.4.6.5 Parking Garage Ventilation Sys- tems. Parking garage ventilation systems shall meet all of the following:

  (1) Separate ventilation systems and control systems shall be provided for each parking garage section.

  (2) Control systems for each parking garage section shall automatically detect and control contaminant levels and shall be capable of and configured to reduce fan airflow to 20 percent or less of design capacity.

  (3) The ventilation system for each parking garage section shall have controls and devices that

  result in fan motor demand of no more than 30 percent of design wattage at 50 percent of the design airflow.

  Exception: Garage ventilation systems serving a single parking garage section having a total ventilation system motor nameplate horsepower (kilowatts)

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  APPENDIX E

  not exceeding 5 hp (3.7 kW) at fan system design conditions and where the parking garage section has no mechanical cooling or mechanical heating.

• CMC § 502.2.4 Medium relevance — show source text

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  CHAPTER 5

  EXHAUST SYSTEMS

  502.2.4 Commercial Kitchen Ducts. Commercial

  kitchens exhaust ducts shall terminate in accordance with

  Section 510.9 for Type I exhaust systems or Section 519.5 for Type II exhaust systems.

  Part I – Environmental Air Ducts and Product-Conveying Systems.

  503.0 Motors, Fans, and Filters.

  503.1 General. Motors and fans shall be sized to provide the required air movement. Motors in areas that contain flammable vapors or dusts shall be of a type approved for such environments. A manually operated remote control installed at an approved location shall be provided to shut off fans or blowers in flammable vapor or dust systems. Equipment used in operations that generate explosive or flammable vapors, fumes, or dusts shall be interlocked with the ventilation system so that the equipment cannot be operated unless the ventilation fans are in operation. Motors for fans used to convey flammable vapors or dusts shall be located outside the duct or shall be protected with approved shields and dustproofing. Where belts are used, they shall not enter the duct unless the belt and pulley within the duct are enclosed. Motors and fans shall be accessible for servicing and maintenance.

  503.2 Fans. Parts of fans in contact with explosive or flammable vapors, fumes, or dusts shall be of nonferrous or nonsparking materials, or their casing shall be lined or constructed of such material. Where the size and hardness of

  materials passing through a fan are capable of producing a spark, both the fan, and the casing shall be of nonsparking materials. Where fans are required to be spark-resistant, their bearings shall not be within the airstream, and parts of the fan shall be grounded. Fans in systems handling materials that are likely to clog the blades, and fans in buffing or woodworking exhaust systems, shall be of the radial-blade or tube-axial type.

  Equipment used to exhaust explosive or flammable vapors, fumes, or dusts shall bear an identification plate stating the ventilation rate for which the system was designed.

  Fans located in systems conveying corrosives shall be of materials that are resistant to the corrosive or shall be coated

  with corrosion-resistant materials.

  504.0 Environmental Air Ducts.

  504.1 General. Where not specified in this chapter, exhaust ducts shall be constructed and installed in accordance with

  Chapter 6 and shall be airtight as approved by the Authority Having Jurisdiction. Environmental air ducts that have an alternate function as a part of an approved smoke control sys

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  501.0 General.

  501.1 Applicability. This chapter includes requirements for environmental air ducts, product-conveying systems, and commercial hoods and kitchen ventilation. Part I addresses environmental air ducts and product conveying systems. Part II addresses commercial hoods and kitchen ventilation.

  502.0 Termination.

  502.1 Exhaust Opening Protection. Exhaust openings terminating to the outdoors shall be covered with a corrosionresistant screen having not less than [1] ⁄ 4 of an inch (6.4 mm) openings, and shall have not more than [1] ⁄ 2 of an inch (12.7 mm) openings.

• CMC § 519.1 Medium relevance — show source text

  519.1 Where Required. Type II hoods shall be installed above equipment and dishwashers that generate steam, heat, or products of combustion, and where grease or smoke is not present.

  Exceptions:

  (1) Dishwashing machines connected to a Type II duct system and exhausted directly to the outdoors.

  (2) Dishwashing machines with a self-contained condensing system listed in accordance with UL 921 and installed in a space where the HVAC system has been engineered to accommodate the latent and sensible heat load emitted from such appliances as approved by the Authority Having Jurisdiction. Such equipment shall be provided with an interlocking device to prevent opening of the appliance prior to completion of its cycle. 519.2 Construction of Type II Hoods. Type II hoods constructed of steel shall be not less than 0.024 of an inch (0.61 mm) (No. 24 gauge). Hoods constructed of copper shall be of copper sheets weighing not less than 0.17 ounces per square inch (oz/in [2] ) (7.47 kg/m [2] ). Joints and seams shall be substantially tight. Solder shall not be used except for sealing a joint or seam. 519.3 Type II Hood Exhaust System Net Airflow. The net airflow for Type II hoods shall be in accordance with Section 508.5.1.5 for light-duty cooking appliances. The net airflow for Type II hoods serving dishwashing appliances shall comply with Section 519.3.1.

  519.3.1 Dishwashing Appliances. The net airflow for Type II hoods used for dishwashing equipment shall be not less than 200 cubic feet per minute (0.094 m [3] /s) per linear foot (m) of hood length.

  519.4 Type II Exhaust Duct Systems. Ducts and plenums serving Type II hoods shall be constructed of rigid metallic materials in accordance with Chapter 6. Duct bracing and supports shall comply with Chapter 6. Ducts subject to positive pressure shall be adequately sealed.

  519.5 Termination of Type II Hood Exhaust System. The exhaust system shall terminate in accordance with Section 502.2.2. Rooftop terminations shall be directed away

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  EXHAUST SYSTEMS

  from roof surfaces within 40 inches (1016 mm). The discharge outlet of moisture conveying exhaust ducts, such as dishwasher exhaust ducts, shall not terminate over a public way or over an area where condensate or vapor could create a nuisance or hazard.

  519.6 Makeup Air. Makeup air shall be provided in accordance with Section 511.3.

  519.7 Independent Exhaust Duct System. Single or combined Type II exhaust systems shall be independent of all other exhaust systems.

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  CALIFORNIA MECHANICAL CODE – MATRIX ADOPTION TABLE

  CHAPTER 6 – DUCT SYSTEMS