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Duct leakage testing. A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating, ventilating and air-conditioning (HVAC) ductwork. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow.
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces. There are two types of natural ventilation occurring in buildings: wind driven ventilation and ...
The conductivity of water is measured in Siemens per meter (S/m). Sea-water is typically 5 S/m, [5] drinking water is typically in the range of 5-50 mS/m, while highly purified water can be as low as 5.5 μS/m (0.055 μS/cm), a ratio of about 1,000,000:1,000:1. Purified water is used in the pharmaceutical industry.
Most modern hot water boiler heating systems have a circulator, which is a pump, to move hot water through the distribution system (as opposed to older gravity-fed systems). The heat can be transferred to the surrounding air using radiators, hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or ...
Variable air volume ( VAV) is a type of heating, ventilating, and/or air-conditioning ( HVAC) system. Unlike constant air volume (CAV) systems, which supply a constant airflow at a variable temperature, VAV systems vary the airflow at a constant or varying temperature. [ 1][ 2] The advantages of VAV systems over constant-volume systems include ...
Demand controlled ventilation (DCV) is a feedback control method to maintain indoor air quality that automatically adjusts the ventilation rate provided to a space in response to changes in conditions such as occupant number or indoor pollutant concentration. The most common indoor pollutants monitored in DCV systems are carbon dioxide and ...
A dedicated outdoor air system ( DOAS) is a type of heating, ventilation and air-conditioning ( HVAC) system that consists of two parallel systems: a dedicated system for delivering outdoor air ventilation that handles both the latent and sensible loads of conditioning the ventilation air, and a parallel system to handle the (mostly sensible ...
An air purge system is used to flush electrical control equipment with clean air before it is turned on. This ensures that the functionality of the equipment is not affected or damaged by the contaminants from the surrounding environment. Air purge systems are employed for control and analytic technology that is exposed to flue gas resulting ...