Search results
Results from the WOW.Com Content Network
The clean air delivery rate (CADR) is a figure of merit that is the cubic feet per minute (CFM) of air that has had all the particles of a given size distribution removed. For air filters that have air flowing through them, it is the fraction of particles (of a particular size distribution) that have been removed from the air, multiplied by the ...
Displacement ventilation systems supply air directly to the occupied zone.The air is supplied at low velocities to cause minimal induction and mixing. This system is used for ventilation and cooling of large high spaces, such as auditorium and atria, where energy may be saved if only the occupied zone is treated rather than trying to control the conditions in the entire space.
Actual cubic feet per minute (ACFM) is a unit of volumetric flow. It is commonly used by manufacturers of blowers and compressors. [1] This is the actual gas delivery with reference to inlet conditions, whereas cubic foot per minute (CFM) is an unqualified term and should only be used in general and never accepted as a specific definition without explanation.
Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour.
At a certain plane in the room, the airflow rate returned to the upper zone is equal to the supply air. The plane divides the room into occupied zone and upper zone and leads to thermal stratification: the hot and contaminated air is concentrated in the upper zone, and the air in the occupied zone is cool and fresh. [2]
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.
In heating, ventilation, and air conditioning (HVAC), testing, adjusting and balancing (TAB) are the three major steps used to achieve proper operation of heating, ventilation, and air conditioning systems. TAB usually refers to commercial building construction and the specialized contractors who employ personnel that perform this service.
The air exchange rate, (I), is the number of interior volume air changes that occur per hour, and has units of 1/h. The air exchange rate is also known as air changes per hour (ACH). ACH is the hourly ventilation rate, divided by the building volume. It can be calculated by multiplying the building's CFM by 60, and then dividing by the building ...