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A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a blower, blower fan, or squirrel-cage fan (because it looks like a hamster wheel).
HVAC (Heating, Ventilation and Air Conditioning) equipment needs a control system to regulate the operation of a heating and/or air conditioning system. [1] Usually a sensing device is used to compare the actual state (e.g. temperature) with a target state. Then the control system draws a conclusion what action has to be taken (e.g. start the ...
The cross-flow or tangential fan, sometimes known as a tubular fan, was patented in 1893 by Paul Mortier, [17] [18] and is used extensively in heating, ventilation, and air conditioning (HVAC), especially in ductless split air conditioners. The fan is usually long relative to its diameter, so the flow remains approximately two-dimensional away ...
Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU) or fresh air handling unit (FAHU). An air ...
Typically, used in industrial or commercial settings, or in "once-through" (blower sections that only blow air one-way into the building), "low flow" (air handling systems that blow air at a low flow rate), or "primary-secondary" (air handling systems that have an air handler or rooftop unit connected to an add-on makeup unit or hood ...
At the air inlet, air temperature must be lower than the upper ambient rating of the fan (typically 50 °C/122 °F). The position of air intake is at a point where the least amount of dust, oil, and moisture collects. Fail safe shutters protect the instrument if the purge air supply fails. These are key in systems where the flue gas is under ...
The Roots-type blower may achieve an efficiency of approximately 70% while achieving a maximum pressure ratio of two. Higher pressure ratios are achievable but at decreasing efficiency. Because a Roots-type blower pumps air in discrete pulses (unlike a screw compressor), pulsation noise and turbulence may be transmitted downstream. If not ...
The air valves are also driven by eccentrics from this same shaft. Like the beam engines, the main force of the piston is transmitted to the air cylinder by a purely reciprocating action and the flywheels exist to smooth the action of the engine. To permit adjustment, the steam piston rod only goes as far as the crosshead. Above this are ...