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Flow measurement and instrument selection of compressed air

      Compressed air is an important secondary energy source for public utilities, and most of it is converted from electrical energy or thermal energy through a compressor. When the air pressure value is lower, it is generated by the blower.
     (1)Characteristics of compressed air flow measurement
      ①The vibration is large.      Air flow meters installed in compression plants and blower rooms must consider vibration issues.This vibration is mainly from the compressor and the blower, and the vibration of the machine can be transmitted to a long distance through the air duct or duct. Among them, the largest vibration is the reciprocating compressor. The vibration generated by the large reciprocating compressor during operation often drives the plant and the surrounding ground to vibrate together, posing a threat to the accurate and reliable operation of the relevant air flow meter.  It triggers the fulcrum movement of the lever differential pressure transmitter to cause the instrument to exhibit an indication drift.  The vibration causes the vortex flow sensor to generate an interference signal corresponding to the vibration frequency, causing the flow indication to be significantly higher.
      ②Gas with water.       Compressed air is taken from the atmosphere, and the atmosphere always contains a certain amount of water vapor.
      ③Pulsating flow.          Most of the compressor and blower outlet fluids contain a certain amount of pulsation. At the site, it is observed that the outlet pressure of the compressor and the blower has a significant swing. Flow arterial motion causes differential pressure flowmeters, vortex flowmeters, and other flowmeters to display high values, causing the floats in the float-type flowmeter to jump up and down.
     (2)Instrument selection
     There are many types of meters that can be used to measure the flow of compressed air, but according to their principles, there are not many types of air flow meters actually used in the field.The most important ones are glass float flowmeters, throttling differential pressure flowmeters, vortex flowmeters and constant velocity tube flowmeters.