Ventilation Systems: General Terminologies You Must Know

Like any other specialty industry, ventilation has its own terminology, definitions, and abbreviations. This important ventilation glossary brings together the most common terms you are likely to hear and is essential to understanding if you want to better understand ventilation.

Air Change per Hour – The amount of air leakage into or out of a building or room in terms of the number of times the building volume or room volume is exchanged.

Axial Flow Fan – A fan with a housing in which air enters and leaves the impeller in a direction substantially parallel to its axis.

Centrifugal Fan – A fan in which air leaves the wheel in a direction substantially perpendicular to its axis.

ContaminantsDust, vapors, gases, mists, vapors, and other substances present in the air which may be harmful or offensive to occupants.

Dilution Ventilation – Supply of outside air to reduce the concentration of pollutants in the air in the building.

Dry Bulb Temperature – The temperature of the air, read on a thermometer, is taken in such a way so as to avoid errors due to radiation.

Effective Temperature (ET)- An arbitrary index that sums up the influence of temperature, humidity, and air movement on the perception of heat or cold perceived by the human body and its numerical value in a single value is that of temperature air still saturated, which would produce an identical sensation.

Exhaust of Air– Extracting air from a building or a room and exhausting it to the outside by means of a mechanical device such as a fan.

Fresh Air or Outside Air – Air of this quality meets the criteria mentioned in norms and must also be such that the concentration of a pollutant in the air is limited to one-tenth of the limit value (ELV) of this pollutant.

General Ventilation – Ventilation, natural or mechanical, or both, to improve the general building environment, as opposed to local exhaust for contamination control.

Globe Temperature – The temperature measured by a thermometer whose bulb is surrounded by a thin copper ball 150 mm in diameter, painted matte black. It combines the influence of air temperature and thermal radiation received or emitted by boundary surfaces.

Also Read, How Doors and Windows affect the Beauty and Ambiance of your home

Humidification – The process of maintaining the absolute humidity of the air in a building at a higher level than that of the outside air, or at a higher level than would occur naturally.

Humidity, Absolute– The mass of water vapor per unit volume.

Humidity, Relative – The ratio of the partial pressure or density of water vapor in the air to the saturation pressure or density of water vapor at the same temperature.

Local Exhaust Ventilation – Ventilation using exhaust air through an exhaust system, such as a safe point of exhaust.

Make-Up Air – Outdoor air that is introduced into a building to replace indoor air.

Mechanical Ventilation – Supply of outside air either by positive ventilation or by infiltration by reducing the pressure inside by air ventilation or by a combination of positive ventilation and rear extract air.

Natural Ventilation – The introduction of outside air into a building through windows or other openings due to the effects of outside wind and convection due to differences in temperature or vapor pressure (or both) between it. interior and exterior of the building.

Positive Ventilation – The supply of outside air by a mechanical device, such as a ventilator or a fan.

Propeller Fan – A fan in which air exits the impeller in a direction substantially parallel to its axis, designed for normal operation with free inlet and outlet conditions.

Spray- Propeller Fan Head System — A water atomizing system to bring free moisture directly into a building.

Stack Effect – Convection effect due to the difference in temperature or vapor pressure (or both) between the outside and the inside of the room and the difference in height between the outlet and inlet openings.

Tropical Summer Index (TSI) The temperature of calm air at 50 percent relative humidity, which conveys the same warm feeling as the given environment.

Threshold Limit Value (TLV)– Refers to the concentration of pollutants in the air currently accepted by the American Conference of Governmental Industrial Hygienists and represents the conditions under which almost all occupants are believed to repeat day after day without adverse effects can be exposed.

Velocity, Capture – The speed of the air at any point in front of the hood that is necessary to overcome opposing drafts and trap contaminants in the air at that location by moving air through the hood.

Ventilation – Bring outside air into a confined space or remove indoor air from a confined space.

Wet Bulb Temperature – The constant temperature, finally indicated by a thermometer, the vial of which is covered with gauze or muslin, moistened with distilled water, and placed in an airstream of at least 4.5 ml.

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