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There are various instruments that can be used to measure air, but in terms of their operating principles, the types of instruments actually used in practice for measuring air flow are not many. The main ones include rotameters, throttling differential pressure flowmeters, vortex flowmeters, and average velocity tube flowmeters. Characteristics of air flow measurement: high vibration, and not every air flow meter is installed in an area with high vibration. However, the air flow meters installed in the compression plant and blower room both need to take vibration into consideration. This vibration mainly comes from the compressor and blowers, and the vibration of the machinery can be transmitted over long distances through air ducts or ventilation pipes. Among them, reciprocating compressors generate the most vibration. The vibration produced by large reciprocating compressors during operation often causes the building and the surrounding ground to vibrate as well, posing a threat to the accurate and reliable operation of the associated air flow meters. It causes the fulcrum of the lever-type differential pressure transmitter to move, resulting in a drift in the instrument’s reading. Vibration causes the vortex flowmeter to generate interference signals at the same frequency as the vibration, resulting in a significantly high reading of the flow rate. 1. For measuring compressed air, flow meters are generally installed in the compressor room and blower room, while the vibrations generated by compressors and blowers can be transmitted over long distances through air pipes or ducts. Vibration causes the vortex flowmeter to generate interference signals at the same frequency as the vibration, resulting in a significantly high reading of the flow rate. 2. Compressed air is drawn from the atmosphere, which always contains a certain amount of water vapor. Large-diameter orifice flow meters used to measure compressed air flow often have water accumulation in front of the orifice, which affects the measurement accuracy. There is often a layer of water in the pressure tap, which causes the differential pressure measured by the differential pressure transmitter to differ from the differential pressure generated by the throttling device. These are all common causes of errors due to water in the air. 3. The fluid at the outlets of compressors and blowers generally contains a certain degree of pulsation. Fluid pulsations can cause the readings of various flow meters, such as differential pressure flow meters and vortex flow meters, to be too high, and they can also cause the rotor in a rotameter to move up and down. To eliminate the effects of pulsation, a buffer tank is generally installed at the compressor’s outlet to remove such pulsations, with the flow meter being placed after the buffer tank ； Or install the flow meter in a location far away from the source of pulsations. 4. The average velocity tube flow meter has unique advantages for measuring air flow at large diameters. Its notable strengths include low cost, simplicity and reliability, as well as ease of installation and maintenance; it serves as a complement to vortex flow meters and throttle differential pressure flow meters. The most commonly used flow meter for measuring compressed air is the vortex flow meter. In locations free from vibration or with minimal vibration, using a vortex flow meter to measure air flow offers significant advantages such as low pressure loss, high accuracy, a wide measurement range, and reduced maintenance requirements. Typically, piezoelectric vortex flowmeters can withstand vibrations of 0.2g. The lower limit of measurable flow velocity under normal pressure conditions is 6 m/s. The capacitive vortex flow meter can withstand vibrations of (0.5–1) g, and under normal pressure conditions, its minimum measurable flow velocity is 4 m/s. In recent years, anti-vibration smart vortex flowmeters have been introduced among vortex flowmeters; these devices offer a wide measurement range of up to 90 m/s, which has made them popular among many users