Air filter in the context of "Catalyst"

Heating, ventilation, and air conditioning (HVAC /ˈeɪtʃˌvæk/) systems use advanced technologies to regulate temperature, humidity, and indoor air quality in residential, commercial, and industrial buildings, and in enclosed vehicles. Its goal is to provide thermal comfort and remove contaminants from the air. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Modern HVAC designs focus on energy efficiency and sustainability, especially with the rising demand for green building solutions. In modern construction, MEP (Mechanical, Electrical, and Plumbing) engineers integrate HVAC systems with energy modeling techniques to optimize system performance and reduce operational costs. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers).

HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.

Indoor air quality (IAQ) is the air quality within buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide, ozone and particulates.

Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality. Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone. In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary.

A fume hood (sometimes called a fume cupboard or fume closet, not to be confused with extractor hood) is a type of local exhaust ventilation device that is designed to prevent users from being exposed to hazardous fumes, vapors, and dusts. The device is an enclosure with a movable sash window on one side that traps and exhausts gases and particulates either out of the area (through a duct) or back into the room (through air filtration), and is most frequently used in laboratory settings.

The first fume hoods, constructed from wood and glass, were developed in the early 1900s as a measure to protect individuals from harmful gaseous reaction by-products. Later developments in the 1970s and 80s allowed for the construction of more efficient devices out of epoxy powder-coated steel and flame-retardant plastic laminates. Contemporary fume hoods are built to various standards to meet the needs of different laboratory practices. They may be built to different sizes, with some demonstration models small enough to be moved between locations on an island and bigger "walk-in" designs that can enclose large equipment. They may also be constructed to allow for the safe handling and ventilation of perchloric acid and radionuclides and may be equipped with scrubber systems. Fume hoods of all types require regular maintenance to ensure the safety of users.

Catalysis (/kəˈtælɪsɪs/, kə-TAL-iss-iss) is the increase in rate of a chemical reaction due to an added substance known as a catalyst (/ˈkætəlɪst/ KAT-əl-ist). Catalysts are not consumed by the reaction and remain unchanged after the reaction. If the reaction is rapid and the catalyst is recycled quickly, a very small amount of catalyst often suffices; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst.

The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease.

Cyclonic separation is a method of removing particulates from an air, gas or liquid stream, without the use of filters, through vortex separation. When removing particulate matter from liquid, a hydrocyclone is used; while from gas, a gas cyclone is used. Rotational effects and gravity are used to separate mixtures of solids and fluids. The method can also be used to separate fine droplets of liquid from a gaseous stream.