ASHRAE Terminology

an assembly that hangs above the stove or cooktop in the kitchen and contains a skirt or capture panel to contain the rising gases or effluent plume, one or more grease filters, and a fan or tangential blower for forced ventilation used to remove airborne grease, combustion products, smoke, odors, heat, and steam from the air by a combination of filtration and evacuation of the air outside of the building. Air extraction cooker hoods may be ducted (or vented) application, or ductless (or recirculating) application. Ductless or recirculating hoods use particulate and gaseous filtration (activated charcoal) to clean the air to an acceptable quality for returning to the room. Hoods may include lighting. See also cooker hood, Hood, Type I Hood, Type II Hood.

(1) ion that is negatively charged (e.g., chloride, silicate, sulfate). Compare to cation. (2) negatively charged ion of an electrolyte that migrates toward the anode influenced by an electric potential gradient.

self acting, operating by its own mechanism when actuated by some nonmanual influence, such as a change in current strength, pressure, temperature, or mechanical configuration.

the first appearance in the effluent of an adsorbate of interest under specified conditions.

the connection to any fuel-fired equipment, device, or appliance and the horizontal section of the exhaust system used for conducting the products of combustion from a fuel-fired equipment, device, or appliance to the vertical section, which is identified as the vent, chimney, or flue.

a wall-mounted or free-standing kitchen hood. Hoods will overhang the appliance(s) on all open sides, which forces replacement air to be drawn across the open sides of the cooking equipment, thus increasing the effectiveness of the hood to capture and contain effluent generated by the cooking operations.

positively charged ion of an electrolyte that migrates toward the cathode influenced by an electric potential gradient.

one or more passageways, vertical or nearly so, for conveying flue gases to the outside atmosphere. Compare to flue or vent.

(1) adjustment of the fuel rate and air/fuel mixture ratio in response to heating load and flue gas air condition over the full range of the burner capacity from some preset minimum to 100%. (2) device or series of devices that control the flow of fuel and combustion air in the desired ratio to provide efficient combustion.

effluents from the combustion of a fuel, including the inerts but excluding excess air.

matter (such as moisture, vapor, products of combustion, smoke, and particulate matter) rising from cooking equipment during equipment operation,.

flue designed to effect the dilution of flue gases with air before discharge from an appliance.

mechanical venting system supplied or recommended by the manufacturer through which the products of combustion pass directly from the furnace or boiler to the outside and which does not employ a means of draft relief. Includes units that have small air passages in the flue that have an opening area that is not in excess of 10% of the cross-sectional area of the stack.

system that provides outdoor air directly to a unit for combustion and for draft relief and which provides for discharge of all flue gases to the outside atmosphere.

(1) current of air, when referring to pressure difference that causes a current of air or gases to flow through a flue, chimney, heater, or space. (2) current of air, when referring to localized effect (generally, the unwanted local cooling of the body caused by air movement) caused by one or more factors of high air velocity, low ambient temperature, or direction of airflow whereby more heat is withdrawn from a person’s skin than is normally dissipated.

a device that is not an integral part of the furnace or boiler and is connected to the furnace or boiler by a short length of flue pipe. It is designed to (a) provide for the exhaust of the products of combustion in the event of no draft, back draft, or stoppage beyond the draft hood, (b) prevent a back draft from entering the furnace, and (c) neutralize the effect of stack action of the chimney or gas vent upon the operation of the furnace.

(1) change in mechanical or electrical characteristics with the passage of time, change in temperature, or both. (2) change in output/input relationship over a period of time with the change unrelated to input, environment, or load. (3) in a cooling tower, water lost as liquid droplets entrained in the exhaust air. It is independent of water lost by evaporation. (4) movement of current carriers in a semiconductor under the influence of an applied voltage.

an eyebrow hood is mounted directly to the face or top of an appliance above the opening(s) or door(s) from which effluent is emitted, overhanging the front of the opening(s) to capture the effluent. Mounting height is fixed.

the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or occurrences of the same (i.e., same defined) event/phenomenon (or the continuation/development of the original phenomenon) in the present or future. When an event is part of a chain of cause and effect that forms a circuit or loop, then the event is said to \"feed back\" into itself. Compare to feed forward.

conduit between the furnace or boiler outlet and the integral draft diverter, draft hood, barometric draft regulator, vent terminal, or any other point of draft relief.

that portion of an appliance designed for attachment to a chimney, vent connector, or a draft hood.

an electrical or mechanical device in the flue outlet or in the inlet of or upstream of the draft control device of an individual, automatically operated, fossil-fuel-fired appliance that is designed to automatically open the flue outlet during appliance operation and to automatically close the flue outlet when the appliance is in a standby condition.

(also known as vent gas), all gases in a flue during combustion in the combustion chamber, including reaction products such as excess air, carbon dioxide, carbon monoxide, oxygen, water vapor, nitrogen, and other inerts.

chamber designed to capture the products of combustion and accompanying excess air.

see flue.

the sum of sensible and latent heat losses above room temperature of the flue gases leaving the furnace or boiler.

opening provided in an appliance for the release of flue gases.

effluent from a cooking process that contains grease particles or grease vapor. This type of exhaust requires a rated hood (e.g., Type I, Type II).

sensible heat carried away by the flue gas and the sensible and latent heat carried away by the water vapor in the flue gas.

a device designed to capture cooking and/or ware washing effluent. See Type I hood and Type II hood.

heat from industrial activities and sources such as wastewater, boiler flue gas, coolants, exhaust air, and some waste materials. This heat is normally wasted unless equipment is included to extract it for further use.

deliberate local control or influencing of user loads to affect the time of use of power or energy such as gas, steam, or electric. Compare with direct-load management.

device consisting of an assembly of parallel sloping vanes, intended to permit the passage of air while providing a measure of protection against environmental influences. Also spelled louvre.

unit for quantifying the source strength of air pollution. One olf is the emission rate of air pollutants (bioeffluents) from a standard person.

small valve where the opening or closing directly influences a larger valve, as in a servo system.

the design that permits the continued operation of the combustion blower in a power vented unit, power burner unit, or forced draft unit for a period of time after the main burner is shut off for the purpose of venting of residual flue gas in the heat exchanger and the venting system.

device to remove fine ash, tars, dusts, or smoke particles from flue gases or other gaseous streams, the device may employ mechanical, electrostatic, or chemical means, or a combination of these. See air cleaner.

(1) movement of air into and out of buildings, chimneys, flue gas stacks, or other containers and is driven by buoyancy. Buoyancy occurs due to a difference in indoor to outdoor air density resulting from temperature and moisture differences. The result is either a positive or negative buoyancy force. The greater the thermal difference and the height of the structure, the greater the buoyancy force, and thus the stack effect. The stack effect is also referred to as the chimney effect, and it helps drive natural ventilation and infiltration. (2) movement of air or other gas in a vertical enclosure (e.g., duct, chimney, building), induced by the density difference between the air or other gas in the enclosure and the ambient atmosphere. Note: stack effect is a significant concern in heating-system design for tall buildings in cold climates. Sometimes referred to as chimney effect. (3) pressure difference caused by the difference in density between indoor and outdoor air due to an indoor/outdoor temperature difference. (4) the vertical airflow within buildings caused by temperature differences between the building's interior and exterior.

temperature below which, in the absence of all external influences, a substance becomes superconducting.

see flue gas.

a device that is located on the outside of a building and may be connected to a furnace or boiler by a system of conduits. It is composed of an air intake terminal through which the air for combustion is taken from the outside atmosphere and an exhaust terminal from which flue gases are discharged.