An air filter and a method of air filtration using the air filter are described. The air filter may comprise a filter media adapted to capture and filter one or more impurities from air. Further, one or more sound wave generators are attached at one or more sides of the filter media. The one or more sound wave generators generate acoustic waves to be propagated into the filter media. The air filter may further comprise a plurality of sensors positioned before the filter media and after the filter media. Further at least one fan is positioned before or after the filter media. Further an IoT is configured to control frequency of the acoustic waves generated by the one or more sound waves generators, and interconnected with power signal control panel parallel, AHU to control rotational speed of the at least one fan based on value provided by the plurality of sensors.

A control system can provide a linear behavior of airflow as a function of damper position of each zone damper in an HVAC system. The control system incrementally closes each zone damper from a fully open position to a fully closed position, and records static pressure measurements with each change in damper position. Then, using a mathematical model that is derived from the second fan law, a correction is calculated for each damper position of each zone damper based on the recorded static pressure measurements to provide corrected damper positions at which the airflow through the zone damper exhibits a linear behavior. The corrected damper positions are stored and used during an operational cycle of the HVAC system to obtain a precise airflow through the zone dampers.

An airflow sensor assembly for an air duct is provided. The airflow sensor assembly includes the air duct having an interior wall and an exterior wall, a high pressure pickup device, a low pressure pickup device, a pressure redirection device, and a pressure sensor. The pressure redirection device is fluidly coupled to the high pressure pickup device and the low pressure pickup device and includes a low inlet, a high inlet, and a common outlet. The pressure sensor is selectively fluidly coupled to the high pressure pickup device and the low pressure pickup device and includes a first inlet and a second inlet. The second inlet is fluidly coupled to the common outlet of the pressure redirection device.

Provided is a fan control apparatus which includes: a first sensor; a second sensor; an RF fan; and a controller. The first sensor is provided in a first room, and is configured to acquire a measured value of at least one condition selected from conditions of atmospheric pressure, temperature, and humidity for the first room, the second sensor is provided in a second room adjacent to the first room, and is configured to acquire a measured value of the same condition as the at least one selected condition for the second room, the RF fan is placed at a boundary between the first and second rooms, and the controller is configured to control a rotational speed and rotational direction of the RF fan in such a manner that the measured values of the first and second sensors are the same.

An access control system receives a trigger command for controlling a ventilation system; determines that the trigger command includes a lock trigger to hold an entrance door in a closed position; and induces a locking differential air pressure between opposite sides of the entrance door in response to the lock trigger, where the locking differential air pressure is sufficient to bias the entrance door to contact or to increase contact with a door frame in the closed position. The access control system may also determine that the trigger command includes an open assist trigger to ease an opening of the entrance door; and may induce an opening differential air pressure between the opposite sides of the entrance door in response to the open assist trigger, where the opening differential air pressure is sufficient to bias the entrance door to reduce contact with the door frame in the closed position.

A motor for a fan, a ventilator, a pump or a compressor includes integrated motor electronics and at least one sensor unit for pressure or volume flow control. The at least one sensor unit may be a module that can be plugged onto or into the integrated motor electronics or may be at least partly integrated into the motor electronics. The motor may be an electronically commutated motor. The integrated motor electronics may be configured to supply the at least one sensor unit with energy.

A method/structure for calibrating a product fluid flow device having one or more apertures with aggregate area A.sub.o, where fluid flows along a fluid flow path therethrough in response to pressure differentials ΔP across the apertures. Calibration is effected relative to a calibration fluid flow device having a geometry and operational parameters corresponding to those of the product fluid flow device. A piecewise curved calibration controller establishes calibration conditions and generates a discrete point calibration flow rate (dpCFR) Function by measuring at a sparse set of points in a range of interest and determining a piecewise curved mathematical representation of fluid flow through the calibration fluid flow device. Data representative of the CFR function is transferred to a product blade controller, which processes the mathematical representation, and controls fluid flow through product fluid flow device based on values extracted from the received dpCFR Function.

An air purifier includes a main body having an inlet and a discharge device mounted on the main body and configured to receive air introduced into the main body through the inlet and discharge the air from the air purifier, wherein the discharge device includes a discharge opening, an opening and closing member including a portion having a size and shape corresponding to the discharge opening, and configured to move out of the discharge opening and into the discharge opening to open and close the discharge opening, and a discharge portion including a plurality of discharge holes, wherein each discharge hole of the plurality of discharge holes has a size smaller than a size of the discharge opening, and wherein the discharge portion has an air discharging area that is variable.

A fluid flow device that can measure and control a flow of a fluid is described. Various procedures, including measuring, controlling, balancing, or calibration procedures can leverage differential pressure measurement. These differential pressure measurements can be measured across the fluid flow device such that a first pressure measurement is taken upstream of the fluid flow device while a second pressure measurement is taken downstream of the fluid flow device. Moreover, one or more of the various pressure measurements, and in particular the downstream pressure measurement, can be performed at stagnation zone where the flow has stagnated. Such can provide significant amplification and/or turndown capabilities.

A problem to be solved by the present disclosure is to realize a fan unit capable of determining occurrence or non-occurrence of a backflow during operation. In a second unit, a second controller calculates front-rear differential pressure by substituting a rotation speed and a volume of air or a wind speed that can be acquired in real time into a relational expression. The relational expression derives, from two values of the rotation speed, the volume of air or the wind speed, and the front-rear differential pressure, the remaining one value. Then, the second controller determines that a backflow occurs if the calculated front-rear differential pressure is within a range that cannot occur under a normal condition. Therefore, the occurrence of a backflow can be detected without using an expensive pressure sensor or a directional wind speed sensor.