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HVAC System

humidity is measured by

The moisture content of air is a significant variable not only in air conditioning for human comfort but also in industrial processing and manufacturing plants, where it can influence the quality of the product. In the spinning of textiles, for example, better results are obtained when humidity is controlled at optimal values. In drying operations, …

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what is a valve

As a mechanical device, a valve should be selected to do the job expected of it and should be properly installed. It will then give long service before it starts to leak or wear out. After installation, and periodically during service, a valve should be checked to ensure that it has the necessary seat tightness …

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artificial ventilation

Where a reliable and positive flow of air for ventilation is required, fans can be installed in a building to extract stale air, which is immediately replaced by fresh air from the outside flowing through gaps around window and door frames, or through purposely designed grilles. Fans in more elaborate ventilation schemes are connected to …

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ventilation in buildings

The simplest ventilation system in a building uses external air as its source, the wind as its motive force, and openings in the external enclosure for fresh air intake on the windward side and stale air extraction on the leeward side . In a tightly constructed building, air infiltration is slow, but in a building …

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stack ventilation

The simplest ventilation system in a building uses external air as its source, the wind as its motive force, and openings in the external enclosure for fresh air intake on the windward side and stale air extraction on the leeward side . In a tightly constructed building, air infiltration is slow, but in a building …

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natural ventilation

The simplest ventilation system in a building uses external air as its source, the wind as its motive force, and openings in the external enclosure for fresh air intake on the windward side and stale air extraction on the leeward side . In a tightly constructed building, air infiltration is slow, but in a building …

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r value units

It is unrealistic to rely on empirical rules to establish forms of constructions which provide satisfactory resistance to heat transfer as well as weather resistance, strength and stability and many of the other performance criteria. Moreover, current construction methods are generally less bulkythan those used years ago, as greatly reduced thicknesses of materials are employed …

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vav system design

Primary Airflow Capabilities All primary air dampers can shut off the primary airflow completely. However, complete shutoff of primary airflow is not recommended if the VAV terminal unit serves a zone that has a heating load If the zone has a heating load, the primary air damper should be specified to have a minimum airflow …

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what is a vav box

Both single-duct and fan-powered VAV terminal units have the same purpose, to provide heating, cooling, and ventilation to the temperature zone (group of spaces controlled by a single zone temperature sensor) that each VAV terminal unit serves. Physical Characteristics Primary Air Inlet Single-duct and fan-powered VAV terminal units have one (typically round) primary air inlet …

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what is an air duct

Ductwork is used to convey air between the air systems and the terminal equipment and spaces which these air systems serve. Construction Common cross-sectional shapes for ductwork are rectangular, round, and flat oval. Rectangular ductwork is normally used for main ducts and runouts to air devices (air inlets and outlets) that have a rectangular neck. …

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