Municipal Code of Chicago tit. 18, ch. 18-28, art. II — Definitions (18-28-201 et seq.) | Municipal Code of Chicago (2026 S-74, current through Council Journal of June 17, 2026) — City of Chicago

Municipal Code of Chicago § 18-28-202 Definitions.

18-28-202 Definitions. ABRASIVE MATERIAL. Moderately abrasive particulate in high concentrations, and highly abrasive particulate in moderate and high concentrations, such as alumina, bauxite, iron silicate, sand and slag. ACCESS (TO). Enables a device, appliance or equipment to be reached by ready access or by a means that first requires the removal or movement of a panel, door or similar obstruction. See Ready Access (to). AIR. All air supplied to mechanical equipment and appliances for combustion, ventilation, cooling and similar processes. Standard air is air at standard temperature and pressure, namely, 70°F (21°C) and 29.92 inches of mercury (101.3 kPa). AIR CONDITIONING. Any treatment of air that simultaneously controls the temperature, humidity, and distribution of the air to meet the requirements of a conditioned space. See conditional space. AIR CONDITIONING SYSTEM. A system that consists of heat exchangers, blowers, filters, supply ducts, exhaust ducts and return ducts, and any apparatus installed in connection with that system. AIR EXHAUST. Air being removed from any space, appliance or piece of equipment and conveyed out-of-doors by means of openings or ducts. AIR-HANDLING UNIT. A blower or fan used to distribute supply air to a room, space or area. AIR MAKEUP. Air that replaces air being exhausted. ALTERATION. As defined in Chapter 14R-2. APPLIANCE. A device or apparatus that is manufactured and designed to utilize energy and for which this chapter provides specific requirements. APPLIANCE, EXISTING. Any appliance regulated by this chapter which was legally installed prior to the effective date of this chapter, or for which an installation permit has been issued. APPLIANCE TYPE. High-heat appliance. Any appliance in which the products of combustion at the point of entrance to the flue under normal operating conditions have a temperature greater than 2,000°F (1093°C). Low-heat appliance (residential appliance). Any appliance in which the products of combustion at the point of entrance to the flue under normal operating conditions have a temperature of 1,000°F (538°C) or less. Medium-heat appliance. Any appliance in which the products of combustion at the point of entrance to the flue under normal operating conditions have a temperature of more than 1,000°F (538°C), but not greater than 2,000°F (1093°C). APPLIANCE UNVENTED. An appliance designed or installed in such a manner that the products of combustion are not conveyed by a vent or chimney directly to the outside atmosphere. APPLIANCE VENTED. An appliance designed and installed in such a manner that all of the products of combustion are conveyed directly from the appliance to the outside atmosphere through an approved chimney or flue vent system. APPROVED. Acceptable to the Building Commissioner. APPROVED AGENCY. An established and nationally recognized agency that is approved by the Building Commissioner that is regularly engaged in conducting tests or furnishing inspection services. AUTOMATIC BOILER. Any class of boiler that is equipped with the controls and limit devices specified in Article X, Boilers, Water Heaters and Pressure Vessels. AUTOMATIC GAS SHUTOFF DEVICE. A device that causes the gas supply in a hot water supply system to shut off when the water temperature exceeds a predetermined limit. AUTOMATIC GAS SHUTOFF VALVE. A valve used in conjunction with an automatic gas shutoff device to shut off the gas supply to a gas-fired water-heating system, including valves that are integral to the construction of the shut off device or that constitute a separate assembly. AUTOMATIC IGNITION. Ignition of gas at the burner(s) when the gas controlling device is turned on, including re-ignition of the burner if the flame on the burner(s) has been extinguished by means other than by closing the gas controlling device. BATHROOM. A room containing a bathtub, shower, spa or similar bathing fixture. BOILER. A closed heating appliance intended to supply hot water or steam for space heating, processing or power purposes. Low-pressure boilers operate at pressures less than or equal to 15 pounds per square inch (psi) (103 kPa) for steam and 60 psi water. High-pressure boilers operate at higher pressures. BRAZED JOINT. A gas-tight joint obtained by the joining of metal parts with metallic mixtures or alloys that have a melting temperature above 800°F (426°C), but lower than the melting temperature of the parts to be joined. BRAZING. A metal joining process whereby coalescence is produced using a nonferrous filler metal which has a melting temperature above 800°F (426°C), but lower than that of the base metal parts being joined. The filler material is distributed between the closely fitted surfaces of the joint by capillary attraction. BTU. Abbreviation for British Thermal Unit, which is the quantity of heat required to raise the temperature of 1 pound (454 g) of water by 1°F (0.56°C) (1 Btu = 1055 J). BUILDING. As defined in Chapter 14B-2. BUILDING PIPING. The piping for fuel from the point where the piping enters the building or foundation up to and including the outlets and upstream to the gas meter or LP-gas or fuel-oil tank outlet. BURNER. A device used for the final conveyance of gas, or a mixture of gas and air, to the combustion zone. Injection (atmospheric) type. A burner into which air at atmospheric pressure is injected by a jet of gas. Injection (Bunsen) type. A burner which uses the energy of a jet of gas to inject air for combustion into the burner and mix it with gas. Luminous or yellow flame. A burner which depends exclusively on secondary air for the combustion of the gas. Power. A burner supplied by gas, air or both in which added pressure is applied at the burner either by gas at pressures exceeding the line pressure, or by air at pressures exceeding the atmospheric pressure, or by both. Premixing. A power burner in which all or nearly all of the air for combustion is mixed with the gas as primary air. Pressure. A burner that is supplied with an air-gas mixture under pressure – usually from 0.5 to 15 inches of water (124 to 3483 Pa) and occasionally higher. CHICAGO BUILDING CODE. Title 14B of the Municipal Code of Chicago. CHICAGO CONSTRUCTION CODES. As defined in Chapter 14A-2. CHICAGO ELECTRICAL CODE. Title 14E of the Municipal Code of Chicago. CHICAGO ENERGY CONSERVATION CODE. Title 14N of the Municipal Code of Chicago. CHICAGO FIRE PREVENTION CODE. Title 14F of the Municipal Code of Chicago. CHICAGO PLUMBING CODE. Title 14P of the Municipal Code of Chicago. CHIMNEY. A primarily vertical structure containing one or more flues, used to carry gaseous products of combustion and air from a fuel-burning appliance to the outside atmosphere. Factory-built chimney. A listed and labeled chimney composed of factory-made components which is assembled in the field in accordance with the manufacturer's instructions and the conditions of its listing. Masonry chimney. A field-constructed chimney composed of solid masonry units, bricks, stones or concrete. CHIMNEY CONNECTOR. A pipe that connects a fuel-burning appliance to a chimney. CLEARANCE. The minimum distance through air measured between the heat-producing surface of a mechanical appliance, device or equipment and the surface of the combustible material or assembly. CLOSED COMBUSTION SOLID-FUEL- BURNING APPLIANCE. A heat-producing appliance that uses a combustion chamber and has no openings other than the flue collar, fuel charging door and adjustable openings to control the amount of combustion air that enters the combustion chamber. CLOTHES DRYER. An appliance used to dry wet laundry by means of heat. COMBUSTIBLE ASSEMBLY. Any wall, floor, ceiling or other assembly constructed of one or more component materials that do not meet the definition of noncombustible. COMBUSTIBLE LIQUIDS. Any liquid having a flash point at or above 100°F (38°C). Combustible liquids are classified as follows: Class II. Any liquids having a flash point at or above 100°F (38°C) and below 140°F (60°C). Class IIIA. Any liquids having a flash point at or above 140°F (60°C) and below 200°F (93°C). Class IIIB. Any liquids having a flash point at above 200°F (93°C). COMBUSTIBLE MATERIAL. Any material not defined as noncombustible. COMBUSTION. In the context of this chapter, refers to the rapid oxidation of fuel accompanied by the production of heat or heat and light. COMBUSTION AIR. Air necessary for complete combustion of a fuel, including theoretical air and excess air. COMBUSTION CHAMBER. The portion of an appliance in which combustion occurs. COMBUSTION PRODUCTS. Constituents resulting from the combustion of a fuel with the oxygen of the air, including the inert gases, but excluding excess air. COMMERCIAL FOOD HEAT-PROCESSING APPLIANCES. Any appliance used in a food- processing establishment to heat-process food or utensils and which produce grease vapors, steam, fumes, smoke or odors that must be removed through a local exhaust ventilation system. Such appliances include, but are not limited to, deep fat fryers, upright broilers, griddles, broilers, fry grills, steam jacketed kettles, hot-top ranges, charbroilers, ovens, barbecues, rotisseries, dishwashing machines, and similar appliances. For the purpose of this definition, a food- processing establishment shall include any building or portion thereof used to process food and food ingredients. COMPRESSOR. A specific machine, with or without accessories, which compresses gas. COMPRESSOR, POSITIVE DISPLACEMENT. A compressor in which an increase in pressure is attained by changing the internal volume of the compression chamber. COMPRESSOR UNIT. A compressor with its prime mover and accessories. CONCEALED GAS PIPING. Piping that is enclosed in the building construction without means of access. CONDENSATE. The liquid that condenses from a gas (including flue gas) and is caused by a reduction in temperature. CONDENSING UNIT. A specific refrigerating machine combination for a given refrigerant, consisting of one or more power-driven compressors, condensers, liquid receivers (when required) and any regularly furnished accessories. CONDITIONED SPACE. An area, room or space being heated or cooled by any equipment or appliance. CONSTRUCTION DOCUMENTS. As defined in Chapter 14A-2. CONTINUOUS PILOT. A pilot that burns without turndown, whether or not the main burner is firing. CONTROL. A manual or automatic device designed to regulate the gas, air, water or electrical supply to, or operation of, a mechanical system. CONVERSION BURNER. A burner designed to supply gaseous fuel to an appliance originally designed to use a different fuel. COOKING APPLIANCE. See Commercial Food Heat-Processing Appliances. CUBIC FOOT. The amount of gas which occupies 1 cubic foot (0.02832 m 3 ) of space when, at a temperature of 60°F (16°C), the gas is saturated with water vapor and placed under a pressure equivalent to that of 30 inches of mercury (101 kPa). DAMPER. A manually or automatically controlled device which regulates draft, or the rate of air flow, or the combustion of gases. Volume damper. A device that, when installed, restricts, retards or directs the flow of air in a duct or the products of combustion in a heat- producing appliance, its vent connector, vent or chimney. DAMPER VENT DEVICE, AUTOMATIC. A device installed either in the outlet or downstream of the appliance draft hood of a venting system of an individual automatically operated fuel-gas-burning appliance. The device is designed to open the venting system automatically when the appliance is in operation and to close off the venting system automatically when the appliance is in a standby or shutdown condition. Automatic damper vent devices may be operated or actuated in the following ways: Electrically operated. Employs electrical energy to control the device. Mechanically actuated. Dependent for operation upon the direct application or transmission of mechanical energy without employing any type of energy conversion. Thermally actuated. Dependent for operation exclusively upon the direct conversion of the thermal energy of the vent gases into mechanical energy. DEMAND. The maximum amount of gas input required per unit of time, usually expressed in cubic feet per hour, or Btu/h (Btu/h = 0.2931 W). DESIGN WORKING PRESSURE. The maximum allowable working pressure for which a specific part of a system is designed. DILUTION AIR. Air that is introduced into a draft hood and is mixed with flue gases. DIRECT REFRIGERATION SYSTEM. A system in which the evaporator or condenser of the refrigerating system is in direct contact with the air or other substances to be cooled or heated. DIRECT VENT APPLIANCES (SEALED COMBUSTION CHAMBER DESIGN APPLIANCES). An appliance that is constructed and installed so that all air for combustion is derived directly from the outside atmosphere and all flue gases are discharged to the outside atmosphere. DIVERSITY FACTOR. The ratio of the maximum probable demand to the maximum possible demand. DRAFT. The pressure difference that exists between an appliance or any of its component parts and the atmosphere, and that causes a continuous flow of air and products of combustion through the gas passages of the appliance to the atmosphere. Induced draft. The pressure difference created by the action of a fan, blower or ejector that is located between the appliance and the chimney or vent termination. Natural draft. The pressure difference created by a vent or chimney because of its height and the temperature difference between the flue gases and the atmosphere. DRAFT HOOD. A device built into an appliance, or made a part of the vent connector from an appliance, that is designed to provide for the ready escape of the flue gases from the appliance in the event of no draft, back draft, or stoppage beyond the draft hood; and to prevent a back draft from entering the appliance; and to neutralize the effect of stack action of the chimney or gas vent upon the operation of the appliance. DRIP. The container placed at a low point in a system of piping to collect condensate and from which the condensate can be removed. DRY CLEANING SYSTEMS. Dry cleaning plants or systems classified as follows: Type I. Those systems using Class I flammable liquid solvents having a flash point below 100°F (38°C). Type II. Those systems using Class II combustible liquid solvents having a flash point at or above 100°F (38°C) and below 140°F (60°C). Type III. Those systems using Class III combustible liquid solvents having a flash point at or above 140°F (60°C). Type IV and Type V. Those systems using Class IV nonflammable liquid solvents. DRY GAS. A gas having a moisture and hydrocarbon dew point below any normal temperature to which the gas piping is exposed. DUCT. A tube or conduit used to convey air. The air passages of self-contained systems are not to be considered as air ducts. DUCT FURNACE. A warm-air furnace normally installed in an air-distribution duct to supply warm air for heating. This definition shall apply only to a warm-air heating appliance that, for air circulation, depends on a blower not furnished as part of the furnace. DUCT SYSTEM. A continuous passageway for the transmission of air, that, in addition to ducts, includes duct fittings, dampers, fans and accessory air handling equipment and appliances. DWELLING UNIT. As defined in Chapter 14B-2. ELECTRICAL HEATING APPLIANCE. An appliance that produces heat energy to create a warm environment by the application of electric power to resistance elements, refrigerant compressors or dissimilar material junctions. ENERGY RECOVERY VENTILATION SYSTEM. A system that employs air-to-air heat exchangers to recover energy from or reject energy to exhaust air for the purpose of preheating, precooling, humidifying or dehumidifying outdoor ventilation air prior to supplying such air to a space, either directly or as part of an heating, ventilation or air conditioning system. EQUIPMENT. All piping, ducts, vents, control devices and other components of any system other than appliances which are permanently installed and integrated to control environmental conditions in a building. This definition shall also include other systems specifically regulated by this chapter. EQUIPMENT, EXISTING. Any equipment regulated by this chapter which was legally installed prior to the effective date of this chapter, or for which a permit to install has been issued. EVAPORATIVE COOLER. A device used to reduce the sensible heat of air for cooling through evaporation of water into an airstream. EVAPORATIVE COOLING SYSTEM. Any equipment and appliance intended or installed for the purpose of environmental cooling which uses an evaporative cooler from which conditioned air is distributed through ducts or plenums to the conditioned area. EXCESS AIR. The amount of air provided in addition to theoretical air to achieve complete combustion of a fuel, thereby preventing the formation of dangerous products of combustion. EXHAUST SYSTEM. An assembly of connected ducts, plenums, fittings, registers, grilles and hoods through which air is conducted and exhausted to the outside atmosphere. FIREPLACE. An assembly consisting of a hearth and fire chamber constructed of noncombustible material and equipped with a chimney for use with solid fuels. Factory-built fireplace. A listed and labeled fireplace and chimney system composed of factory-made components, and assembled in the field in accordance with the manufacturer's instructions and the conditions of its listing. Masonry fireplace. A field-constructed fireplace composed of solid masonry units, bricks, stones or concrete. FIREPLACE STOVE. A chimney-connected, solid-fuel burning stove (appliance) which has part of its fire chamber open to the room. FLAME SAFEGUARD. A device that automatically shuts off the fuel supply to a main burner or group of burners when the means of ignition of such burners becomes inoperative, and when flame failure occurs on the burner or group of burners. FLAME SPREAD INDEX. As defined in Chapter 14B-2. FLAMMABILITY CLASSIFICATION. Refrigerants shall be assigned to one of the three classes – 1, 2 or 3 – in accordance with ASHRAE 34. For Classes 2 and 3, the heat of combustion shall be calculated based on the assumption that the combustion products are in a gas phase and in their most stable state. Class 1A. Refrigerants that do not show flame propagation when tested in air at 14.7 psia (101 kPa) and 70°F (21°C). Class 1B. Refrigerants having a lower flammability limit (LFL) of more than 0.00625 pound per cubic foot (0.10 kg/m3) at 70°F (21°C) and 14.7 psia (101 kPa) and a heat of combustion of less than 8,174 Btu/lb. (19000 kJ/kg). Class 1C. Refrigerants that are highly flammable and have a LFL of less than or equal to 0.00625 pound per cubic foot (0.10 kg/m3) at 70°F (21°C) and 14.7 psia (101 kPa) or a heat of combustion greater than or equal to 8,174 Btu/lb. (19000 kJ/kg). FLAMMABLE LIQUIDS. Any liquid that has a flash point below 100°F (38°C). Flammable liquids shall be known as Class I liquids and shall be divided into the following classifications: Class IA. Liquids having a flash point below 73°F (23°C) and having a boiling point below 100°F (3 8°C). Class IB. Liquids having a flash point below 73°F (23°C) and having a boiling point at or above 100°F (38°C). Class IC. Liquids having a flash point at or above 73°F (23°C) and having a boiling point below 100°F (38°C). FLAMMABLE VAPOR OR FUMES. Any mixture of gases in the air at concentrations equal to or greater than the lower flammability limit (LFL) and less than or equal to the upper flammability limit (UFL). FLASH POINT. The minimum temperature corrected to a pressure of 14.7 psia (101 kPa) at which the application of a test flame causes the vapors of a portion of the sample to ignite under the conditions specified by the test procedures and apparatus. The flash point of a liquid shall be determined in accordance with ASTM D 56, ASTM D 93 or ASTM D 3278. FLOOD ZONES. Areas determined in accordance with Chapter 16-6. Flood-hazard zone. Areas that have been determined to be prone to flooding, but not subject to high-velocity waters or wave action. High-hazard zone. Areas of tidal influence determined to be subject to wave heights in excess of 3 feet (914 mm) or subject to high-velocity wave run up or wave-induced erosion. FLOOR FURNACE. A completely self-contained furnace installed on the floor of the space being heated which takes air for combustion from outside the space and is equipped with means to observe flames and to light the appliance from within the space. FREE AREA. If louvered, grilled or screened openings are used to supply air for gas appliances, the "free area" of the opening is the actual area through which air can flow. FLUE. A passageway within a chimney or vent through which gaseous combustion products exit a system. FLUE CONNECTION (BREECHING). A passage which conducts the products of combustion from a fuel-fired appliance to the vent of chimney. See also Chimney Connector and Vent Connector. FLUE GASES. Products of combustion and excess air. FUEL OIL. Kerosene or any hydrocarbon oil having a flash point of not less than 100°F (38°C). FUEL-OIL PIPING SYSTEM. A closed piping system that connects a combustible liquid from a source of supply to a fuel oil-burning appliance. FURNACE. A completely self-contained heating unit that is designed to supply heated air to spaces remote from or adjacent to the appliance location. FUSIBLE PLUG. A device arranged to relieve pressure by operation of a fusible member at a predetermined temperature. GAS CONVENIENCE OUTLET. A permanently mounted, manually operated device that provides the means for connecting an appliance to, and disconnecting an appliance from, the gas supply piping. The device includes an integral, manually operated gas valve with a nondisplaceable valve member and is designed so that the appliance can only be disconnected when the manually operated gas valve is in the closed position. GAS PIPING. An installation of pipe, valves or fittings installed on a premises or in a building and used to convey fuel gas. HAZARDOUS LOCATION. Any location considered to be a fire hazard for flammable vapors, dust, combustible fibers or other highly combustible substances. The location is not necessarily categorized in the Chicago Building Code as a high-hazard use group classification. HEAT EXCHANGER. A device that transfers heat from one medium to another. HEAT PUMP. A refrigeration system that extracts heat from one substance and transfers it to another portion of the same substance or to a second substance at a higher temperature for a beneficial purpose. HEAT TRANSFER LIQUID. The operating or thermal storage liquid in a mechanical system, including water or any other liquid base and additives at the concentration present under operating conditions used to move heat from one location to another. Refrigerants are not heat transfer liquids. HIGH-PROBABILITY SYSTEMS. A refrigeration system in which the basic design or location of components is such that a leakage of refrigerant from a failed connection, seal or component will enter an occupancy classified area other than the machinery room. HIGH-SIDE PRESSURE. The parts of a refrigerating system subject to condenser pressure. HOOD. An air-intake device used to capture, by entrapment, impingement, adhesion or similar means, grease and similar contaminants before they enter a duct system. Type I. A kitchen hood for collecting and removing grease vapors and smoke. Type II. A general kitchen hood for collecting and removing steam, vapor, heat and odors. HOUSE PIPING. See Building Piping. IDLH (IMMEDIATELY DANGEROUS TO LIFE OR HEALTH). The concentration of airborne contaminants that poses a threat of death, immediate or delayed permanent adverse health effects, or effects that could prevent escape from such an environment. This contaminant concentration level is established by the National Institute of Occupational Safety and Health (NIOSH) based on both toxicity and flammability. It is generally expressed in parts per million by volume (ppm v/v) or milligrams per cubic meter (mg/m 3 ). IGNITION PILOT. A pilot that operates during the lighting cycle and discontinues operation during the main burner operation. IGNITION SOURCE. A flame, spark or hot surface capable of igniting flammable vapors or fumes. Such sources include appliance burners, burner ignitors and electrical switching devices. INDIRECT REFRIGERATION SYSTEM. A system in which a secondary coolant cooled or heated by the refrigerating system, is circulated to the air or to any other substance to be cooled or heated. Indirect systems are distinguished by the method of application shown described below: Closed system. A system in which a secondary fluid is either cooled or heated by the refrigerating system and is then circulated within a closed circuit in indirect contact with the air or other substance to be cooled or heated. Double-indirect open-spray system. A system in which the secondary substance for an indirect open spray system is heated or cooled by an intermediate coolant circulated from a second enclosure. Vented closed system. A system in which a secondary coolant is cooled or heated by the refrigerating system and then passed through a closed circuit in the air or other substance to be cooled or heated, provided that the evaporator or condenser is placed in an open or appropriately vented tank. INTERMITTENT PILOT. A pilot that operates during the ignition cycle and continues to operate during the main burner operation, but is shut off at other times. JOINT, FLANGED. A joint made by bolting together a pair of flanged ends. JOINT, FLARED. A metal-to-metal compression joint in which a conical spread is made on the end of a tube that is compressed by a flare nut against a mating flare. JOINT, MECHANICAL. A general form of gas- tight joints obtained by the joining of metal parts through a positive-holding mechanical construction, such as a flanged joint, screwed joint or flared joint. JOINT, PLASTIC ADHESIVE. A joint made in thermoset plastic piping using an adhesive substance which forms a continuous bond between the mating surfaces. JOINT, PLASTIC SOLVENT CEMENT. A joint made in thermoplastic piping by using a solvent or solvent cement which forms a continuous bond between the mating surfaces. JOINT, SOLDERED. A gas-tight joint obtained by joining metal parts with metallic mixtures of alloys which melt at temperatures between 400°F (204°C) and 800°F (426°C). JOINT, WELDED. A gas-tight joint obtained by the joining of metal parts in a molten state. LABELED. As defined in Chapter 14B-2. LARGE-DIAMETER CEILING FAN. A ceiling fan that is greater than 7 feet (2134 mm) in diameter. These fans are also referred to as high-volume, low-speed (HVLS) fans. LEL (LOWER EXPLOSIVE LIMIT). See also LFL. LFL (LOWER FLAMMABILITY LIMIT). The minimum concentration of refrigerant capable of propagating a flame through a homogeneous mixture of refrigerant and air. LIMIT CONTROL. A device responsive to changes in pressure, temperature or level for turning on, shutting off or throttling the gas supply to an appliance. LIMITED CHARGE SYSTEM. A system which uses a compressor idle to ensure that the design system's pressure is not exceeded if the refrigerant charge completely evaporates. LIQUEFIED PETROLEUM GAS or LPS (LP-GAS). Liquefied petroleum gas composed predominately of propane, propylene, butanes, butylenes or any mixture thereof that is gaseous under normal atmospheric conditions, but is capable of being liquefied under moderate pressure at normal temperatures. LISTED. As defined in Chapter 14B-2. LOG-LIGHTER, GAS-FIRED. A manually operated, gas-fired solid-fuel ignition device for installation in a vented solid-fuel-burning fireplace. LOW-PRESSURE GAS SUPPLY SYSTEM. A gas supply system with gas pressure at or below 6 inches 0.5 psig (3.4 kPa gauge) of water column. LOW-PRESSURE STEAM-HEATING BOILER. A boiler furnishing steam at pressures not exceeding 15 psi (103 kPa). LOW-SIDE PRESSURE. The parts of a refrigerating system subject to evaporator pressure. MACHINERY ROOM. A room meeting prescribed safety requirements and in which refrigeration systems or components thereof are located. See Sections 18-28-1105, Machinery Room General Requirements and 18-28-1106, Machinery Room Special Requirements. MAIN BURNER. A device or group of devices that essentially forms an integral unit for the final conveyance of gas or a mixture of gas and air to the combustion zone, and on which combustion takes place to accomplish the function for which the appliance is designed. MAIN BURNER CONTROL VALVE. A valve that controls the gas supply to the main burner manifold. MANUAL SHUTOFF VALVE. A manually operated, listed gas valve in the gas line used to completely turn on or shut off the gas supply. MEASURED GAS. Gas that has passed through a meter which has measured its volume or gas that has been otherwise measured such as by weight or volume. MECHANICAL EXHAUST SYSTEM. A system that removes air from a building by mechanical means to the out-of-doors. MECHANICAL JOINT. A connection between pipe, fittings or pipes and fittings which is not screwed, caulked, threaded, soldered, solvent cemented, brazed or welded. A mechanical joint also includes a joint in which compression is applied along the centerline of the pieces being joined. Some mechanical joints are part of a coupling, fitting or adapter. MECHANICAL SYSTEM. A system specifically addressed and regulated by this chapter and comprising components, devices, appliances and equipment. MEDIUM-PRESSURE GAS SUPPLY SYSTEMS. A gas supply system with gas pressure exceeding 0.5 psig (3.4 kPa gauge), but not exceeding 5 psig (34 kPa gauge). METER. The instrument installed to measure the volume of gas delivered through it. MODULAR BOILER. A steam or hot water heating assembly consisting of a group of individual boilers called modules and intended to be installed as a unit with no intervening stop valves. Modules are under one jacket or are individually jacketed. The individual modules shall be limited to a maximum input rating of 400,000 Btu/h (117,228 W) gas, 3 gallons per hour (gph) (11.4 L/h) oil, or 115 kW (electric). MP REGULATOR, 2 PSI (13.8 kPa). A medium- pressure regulator that reduces the 2 psi (13.8 kPa) consumer's gas piping pressure to the appliance regulator or to the appliance utilization pressure. NATURAL VENTILATION. The movement of air into and out of a space through intentionally provided openings, such as windows and doors, or through non-powered ventilators. NATURAL DRAFT VENTING SYSTEM. A venting system designed to remove flue or vent gases under non-positive static vent pressure entirely by natural draft. NONABRASIVE/ABRASIVE MATERIALS. Nonabrasive particulate in high concentrations, moderately abrasive particulate in high concentrations, moderately abrasive particulate in low and moderate concentrations, and highly abrasive particulate in low concentrations, such as alfalfa, asphalt, plaster, gypsum and salt. NONCOMBUSTIBLE MATERIALS. Materials that, when tested in accordance with ASTM E 136, are found to have at least three of every four specimens tested meet all of the following criteria: 1. The recorded temperature of the surface and interior thermocouples does not at any time during the test rise more than 54°F (30°C) above the furnace temperature at the beginning of the test. 2. There is no flaming from the specimen after the first 30 seconds. 3. The weight loss of the specimen during testing exceeds 50 percent and the recorded temperature of the surface and interior thermocouples does not at any time during the test rise above the furnace air temperature used at the beginning of the test, and there is no flaming of the specimen. OCCUPANCY. The purpose for which a building, or portion thereof, is utilized or occupied. ORIFICE. The opening in a cap, spud or other device whereby the flow of gas is limited and through which the gas is discharged to the burner. ORIFICE CAP (HOOD). A movable fitting having an orifice that permits the flow of gas to be adjusted by changing its position with respect to a fixed needle or other device. ORIFICE SPUD. A removable plug or cap containing an orifice that permits the flow of gas to be adjusted either by substitution of a spud with a different-sized orifice or by the motion of a needle with respect to it. OUTDOOR AIR. Air taken from the outdoors, and therefore not previously circulated through the system. OUTDOOR OPENING. A door, window, louvre or skylight that can be opened to the outside atmosphere. OUTLET. A threaded connection or bolted flange in a piping system to which a gas-burning appliance is attached. OXYGEN DEPLETION SAFETY SHUTOFF SYSTEM (ODS). A system designed to shut off the gas supply to the main and pilot burners if the oxygen in the surrounding atmosphere is reduced below a predetermined level. PANEL HEATING. A method of radiant space heating in which heat is supplied by large heated areas of room surfaces. The heating element usually consists of warm water piping, warm air ducts, or electrical resistance elements embedded in or located behind ceiling, wall or floor surfaces. PELLET FUEL-BURNING APPLIANCE. A closed-combustion, vented appliance equipped with a fuel-feed mechanism for burning processed pellets of solid fuel of a specified size and composition. PIPING. Piping refers to either pipe or tubing, or both. Pipe. A rigid conduit of iron, steel, copper, brass or plastic. Tubing. A semirigid conduit of copper, aluminum, plastic or steel. PLASTIC THERMOPLASTIC. A plastic capable of being repeatedly softened by increasing its temperature and hardened by decreasing its temperature. PLASTIC THERMOSETTING. A plastic that is capable of being changed into a substantially infusible or insoluble product when cured under application of heat or chemical means. PLENUM. An enclosed portion of the building structure, other than an occupiable space being conditioned, that is designed to allow air movement, and thereby serves as part of an air distribution system. POLLUTION-CONTROL UNIT (PCU). Manufactured equipment that is installed in a grease exhaust duct system for the purpose of extracting smoke, grease particles and odors from the exhaust flow by means of a series of filters. POWER BOILER. See Boiler. PREMISES. A lot, plot or parcel of land, including any structure thereon. PRESSURE FIELD TEST. A test performed in the field to prove system tightness. PRESSURE-LIMITING DEVICE. A pressure-responsive any mechanism designed to stop automatically the operation of any pressure-imposing element at a predetermined pressure. PRESSURE-RELIEF DEVICE. A pressure-actuated valve held closed by a spring or other means and designed to relieve pressure in excess of the device's setting automatically. PRESSURE-RELIEF VALVE. A pressure-actuated valve or rupture member designed to relieve excessive pressure automatically. PRESSURE VESSELS. Closed containers, tanks or vessels designed to contain liquids, gases or both, under pressure. PRESSURE VESSELS – REFRIGERANT. Any refrigerant-containing receptacle in a refrigerating system. This term does not include evaporators where each separate section does not exceed 0.5 cubic foot (0.014 m 3 ) of refrigerant-containing volume, regardless of the maximum inside dimensions, evaporator coils, controls, headers, pumps and piping. PURGE. To clear of air, water or other foreign substances. QUICK-DISCONNECT DEVICE. A hand-operated device that provides a means to connect and disconnect an appliance or an appliance connector to a gas supply and that is equipped with an automatic means to shut off the gas supply when the device is disconnected. RADIANT HEATER. A heater designed to transfer heat primarily by direct radiation. READY ACCESS (TO). A device, appliance or equipment that can be directly reached without requiring the removal or movement of any panel, door or similar obstruction. See Access To. RECEIVER LIQUID. A vessel permanently connected to a refrigeration system by inlet pipes for storage of liquid refrigerant. RECIRCULATED AIR. Air removed from a conditioned space and intended for reuse as supply air. RECLAIMED REFRIGERANTS. Refrigerants reprocessed to the same specifications as required for new refrigerants by means such as distillation. Reclaimed refrigerants have been chemically analyzed to verify that the specifications have been met. Reclaiming usually implies the use of processes or procedures that are available only at a reprocessing or manufacturing facility. RECOVERED REFRIGERANTS. Refrigerants removed from a system in any condition without necessarily testing or processing them. RECYCLED REFRIGERANTS. Refrigerants from which contaminants have been reduced by oil separation, removal of noncondensable gases, and single or multiple passes through devices that reduce moisture, acidity and particulate matter, such as replaceable core filter driers. These procedures usually are performed at the field job site or in a local service shop. REFRIGERANT. A substance utilized to produce refrigeration by its expansion or vaporization. REFRIGERANT SAFETY CLASSIFICATION. Groupings that indicate the toxicity and flammability classes in accordance with Section 18-28-1103.1. The classification group is made up of a letter (A or B) that indicates the toxicity class, followed by a number (1, 2 or 3) that indicates the flammability class. Refrigerant blends are similarly classified, based on the compositions at their worst cases of fractionation, as separately determined for toxicity and flammability. In some cases, the worse case of fractionation is the original formulation. Flammability. Class 1. Indicates refrigerants that do not show flame propagation in air when tested by prescribed methods at specified conditions. Classes 2 and 3. Indicate refrigerants with "lower flammability" and "higher flammability" respectively; the distinction depends on both the lower flammability limit (LFL) and heat of combustion. Toxicity. Classes A and B. Indicate refrigerants with "lower toxicity" and "higher toxicity" respectively, based on prescribed measures of chronic toxicity. REFRIGERATED ROOM OR SPACE. A room space in which an evaporator or brine coil is located for the purpose of reducing or controlling the temperature within the room or space to below 68°F (20°C). REFRIGERATION SYSTEM. A combination of interconnected refrigerant-containing parts constituting one closed refrigerant circuit in which a refrigerant is circulated for the purpose of extracting heat. REFRIGERATION CAPACITY RATING. Whether expressed as 1 horsepower (0.5 kW), or 1 ton or 12,000 Btu/h (3.5 kW), all of these ratings indicate the same quantity. REFRIGERATION SYSTEM, ABSORPTION. A heat-operated, closed-refrigeration cycle in which a secondary fluid (the absorbent) absorbs a primary fluid (the refrigerant) that has been vaporized in the evaporator. Direct system. A system in which the evaporator is in direct contact with the material or space refrigerated, or is located in air-circulating passages communicating with such spaces. Indirect system. A system in which a brine coil cooled by the refrigerant is circulated to the material or space refrigerated, or is utilized to cool the air circulated. Indirect systems are distinguished by the type or method of application. REFRIGERATION SYSTEM CLASSIFICATION. Refrigeration systems classified according to the degree of probability that leaked refrigerant from a failed connection, seal or component will enter an occupied area. The distinction is based on the basic design or location of the components. REFRIGERATION SYSTEM, MECHANICAL. A complete factory-assembled and tested system that is shipped in one or more sections and has no refrigerant-containing parts that are joined in the field by other than companion or block valves. REGISTERED DESIGN PROFESSIONAL. An architect or engineer who is registered or licensed to practice professional architecture or engineering, as defined by the statutory requirements of the professional registration laws of the state in which the project is to be undertaken or constructed. REGULATOR. A device to control and maintain a uniform gas supply pressure, using either a pounds- to-inches water column (MP regulator) or an inches- to-inches water column (appliance regulator). REGULATOR, LINE GAS PRESSURE. A device placed in a gas line between the service pressure regulator and the gas appliance to control, maintain or reduce the pressure in that portion of the piping system downstream of the device. REGULATOR, LP-GAS, FIRST STAGE. On an undiluted LP-gas system, the first pressure regulator reduces the storage container pressure. REGULATOR, SERVICE PRESSURE. A device installed by the serving gas supplier to reduce and limit service line gas pressure to delivery pressure. RETURN AIR. Air removed from an approved conditioned space or location and recirculated or exhausted. RETURN AIR SYSTEM. An assembly of connected ducts, plenums, fittings, registers and grilles through which air from the space or spaces to be heated or cooled is conducted back to the supply unit. See also Supply Air System. RISER GAS. A vertical pipe supplying fuel gas. ROOM HEATER, UNVENTED. See Unvented Room Heater. ROOM HEATER, VENTED. A freestanding heating unit that burns solid, liquid or gas fuel in order to heat directly the space in which the unit is located and any adjacent space. See Vented Room Heater (Gas-Fired). SAFETY SHUTOFF DEVICE. A device that shuts off the gas supply to controlled burners if the source of ignition fails to ignite the gas at the burners. This device interrupts the flow of gas to the main burners, or to the pilot and the burners or to the pilot and burners under the safety shutoff device control. SAFETY VALVE. A valve that relieves pressure in a steam boiler by opening fully at the rated discharge pressure. The valve is of the spring-pop type. SELF-CONTAINED EQUIPMENT. Complete, factory-assembled and tested, heating, air conditioning or refrigeration equipment installed as a single unit, and having all working parts, complete with motive power, in an enclosed unit. SERVICE PIPE. The pipe that brings the gas from the gas main to the point of delivery. SHAFT. As defined in Chapter 14B-2. SHAFT ENCLOSURE. As defined in Chapter 14B-2. SLEEPING UNIT. As defined in Chapter 14B-2. SMOKE DAMPER. As defined in Chapter 14B-2. SMOKE-DEVELOPED INDEX. As defined in Chapter 14B-2. SOURCE CAPTURE SYSTEM. A mechanical exhaust system designed and constructed to capture air contaminants at their source and to exhaust them to the outdoor atmosphere. SPACE, CONFINED. A space with a volume less than 50 cubic feet per 1,000 Btu per hour (20 Btu per hour per cubic foot) of the aggregate input rating of all appliances installed in that space. SPACE, UNCONFINED. A space with a volume greater than or equal to 50 cubic feet per 1,000 Btu per hour (20 Btu per hour per cubic foot) of the aggregate input rating of all appliances installed in the space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered to be a part of the unconfined space. SPECIFIC GRAVITY. As applied to gas, specific gravity is the ratio of the weight of a given volume of gas to that of the same volume of air when both are measured under the same condition. STEAM HEATING BOILER. A boiler operated at pressures not exceeding 15 psi (103 kPa) for steam. STOCK COCK. See Manual Shutoff Valve. STOP VALVE. A shutoff valve to control the flow of liquid or gases. STORY. As defined in Chapter 14B-2. STRENGTH, ULTIMATE. The highest stress level that component will tolerate without rupture. SUPPLY AIR. That air delivered to each or any space supplied by an air distribution system or the total air delivered to all spaces supplied by an air distribution system, which is used to ventilate, heat, cool, humidify and dehumidify the space and for other similar purposes. SUPPLY AIR SYSTEM. An assembly of connected ducts, plenums, fittings, registers and grilles through which air, heated or cooled, is conducted from the supply unit to the space or spaces to be heated or cooled. See also Return Air System. THEORETICAL AIR. The exact amount of air required to supply the oxygen necessary for complete combustion of a given quantity of a specific fuel. THERMAL RESISTANCE (R). A measure of a material's ability to retard the flow of heat. The R- value is the reciprocal of thermal conductance. THIRD-PARTY CERTIFICATION AGENCY. An approved agency operating a product or material certification system that incorporates initial product testing, assessment and surveillance of a manufacturer's quality control system. THIRD-PARTY CERTIFIED. Certification obtained by the manufacturer indicating that the function and performance characteristics of a product or material have been determined by testing and ongoing surveillance by an approved third-party certification agency. Assertion of certification is in the form of identification in accordance with the requirements of the third-party certification agency. THIRD-PARTY TESTED. Procedure by which an approved testing laboratory provides documentation that a product, material or system conforms to specified requirements. TLV-TWA (THRESHOLD LIMIT VALUE- TIME-WEIGHTED AVERAGE). The time-weighted average concentration of a refrigerant or other chemical in air for a normal 8-hour workday and a 40-hour workweek, to which nearly all workers are repeatedly exposed, day after day, without adverse effects, as determined by the American Conference of Government Industrial Hygienists (ACGIH). TOILET ROOM. A room containing a water closet and, frequently, a lavatory, but not a bathtub, shower, spa or similar bathing fixture. TOXICITY CLASSIFICATION. Refrigerants shall be classified for toxicity into one of two classes, in accordance with ASHRAE 34. Class A. Refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 parts per million (ppm) based on data used to determine Threshold Limit Value-Time-Weighted Average (TLV-TWA) or consistent indices. Class B. Refrigerants for which there is evidence of toxicity at concentrations below 400 ppm, based on data used to determine Threshold Limit Value-Time-Weighted Average (TLV-TWA) or consistent indices. TRANSITION FITTINGS, PLASTIC TO STEEL. An adapter used to join plastic pipe to steel pipe in order to provide a permanent, pressure-tight connection between two materials which cannot be joined directly one to the other. UNIT HEATER. A self-contained appliance of the fan type, designed to deliver warm air directly into the space in which the appliance is located. UNVENTED ALCOHOL FUEL-BURNING DECORATIVE APPLIANCE. A stationary, self-contained appliance intended to be permanently secured to a wall or floor and not intended for duct connection. Such appliance burns alcohol and is made in a manufacturing facility for subsequent delivery to the installation site. VENT. A pipe or other conduit composed of factory-made components, containing a passageway for conveying combustion products and air to the atmosphere, listed and labeled for use with a specific type or class of appliance. Pellet vent. A vent listed and labeled for use with listed pellet fuel-burning appliances. Type L vent. A vent listed and labeled for use with oil-burning appliances that are listed for use with Type L vents. VENT CONNECTOR. The pipe that connects an approved fuel-fired appliance to a vent. VENT DAMPER DEVICE, AUTOMATIC. A device intended for installation in the venting system, in the outlet of an individual automatically operated fuel-burning appliance that is designed to open the venting system automatically when the appliance is in operation and to close off the venting system automatically when the appliance is in a standby or shutdown condition. VENTILATION. The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, any space. VENTILATION AIR. That portion of supply air that comes from the outside (outdoors), plus any recirculated air that has been treated to maintain the desired quality of air within a designated space. VENTING SYSTEM. A continuous open passageway from the flue collar of an appliance to the outside atmosphere for the purpose of removing flue or vent gases. A venting system is usually composed of a vent or a chimney and vent connector, if used, assembled to form the open passageway. WATER HEATER. Any heating appliance or equipment that heats potable water and supplies such water to the potable hot water distribution system. (Amend Coun. J. 11-13-07, p. 14999, Art. II, § 1; Amend Coun. J. 11-8-12, p. 38872, § 317; Amend Coun. J. 9-14-21, p. 35949, Art. II, § 2)

Definitions (18-28-201 et seq.)

Municipal Code of Chicago § 18-28-201.1 Scope.

Municipal Code of Chicago § 18-28-201.2 Interchangeability.

Municipal Code of Chicago § 18-28-201.3 Terms defined in other code provisions.

Municipal Code of Chicago § 18-28-201.4 Terms not defined.

Municipal Code of Chicago § 18-28-202 Definitions.