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Ventilation ducts, also simply referred to as air ducts, are metal or composite pipes used in ventilation and air conditioning systems in industrial and residential buildings. They constitute a type of municipal infrastructure designed to facilitate air circulation and reduce the concentration of harmful gases. Ventilation ducts, as products commonly found in our daily lives today, are widely used in various applications, such as ventilation in industrial buildings, underground spaces, safety ventilation, and the agricultural sector. Flow in pipes within ventilation ducts is caused by the pressure difference between the gases at the two ends of the pipe. Except for high-temperature gases, the flow is isochoric; as the cross-sectional area changes, the flow rate changes accordingly, and dynamic pressure and static pressure within the pipe convert into one another. Therefore, “pipe flow velocity” is commonly used to denote the flow rate in a closed pipe under pressure. Closed conduits are usually circular, but can also be square or rectangular. Another major category of flow is open-channel flow, which occurs when the free surface of the liquid is exposed to atmospheric pressure. For various purposes, it is necessary to measure the flow rate of fluids flowing under pressure. The ISweek Industrial Network gas flow sensor – AFE-01 consists of four platinum thin-film resistors, features low impedance, and has a small heating area. There is a high-impedance resistor on each side of the heater, used to detect flow rate and direction; there is also a resistor for detecting the temperature of the gas. The two resistors located near the heating element are connected to form a bridge, which generates an output signal that indicates the flow rate and direction. In the absence of current, these two resistors reach the same heating state. When there is flow, the temperature of one of the resistors is much lower than that of the other; which resistor has the lower temperature depends on the direction of flow. The temperature difference can be measured, and it is determined by the flow rate and direction of flow. The heating time and response time of the flow sensor are very short due to its low thermal mass. This method can detect very slight changes in flow velocity. To achieve a higher flow rate, the temperature sensor can be connected to a constant-temperature anemometer. Furthermore, the gas flow sensor AFE-01 is manufactured by a European specialist in flow sensors; it features a very small size, the ability to detect flow in both directions, detection of flow from small mass objects, a simple signal processing circuit along with calibration functions, completely fixed mechanical components, and excellent repeatability and long-term stability. These characteristics make it suitable for use in the medical and instrumentation industries, as well as by OEM customers.