The compressed air flow meter is a velocity meter that measures the flow of gas media in closed pipelines. It has been widely used in compressed air flow measurement in various fields such as metallurgy, petroleum, chemical industry, energy, food, and environmental protection. . Compressed air flow meters can display real-time temperature, real-time pressure, instantaneous flow, and flow accumulation. They are generally suitable for measuring various non-corrosive gases, such as natural gas, air, etc. Some flow meters can also measure corrosive gases.

Taiwan dpc will answer your questions about the working principle of the compressed air flow meter

The basic principle of the compressed air flow meter is the Karman vortex principle, that is, "the vortex separation frequency is proportional to the flow rate" . The diameter of the transmitter flow body is basically the same as the nominal diameter of the instrument.

A cylinder approximately in the shape of an isosceles triangle is inserted into the circulation body. The axis of the cylinder is perpendicular to the flow direction of the measured medium, and the bottom surface faces the fluid.

When the measured compressed air flows through the cylinder, vortices are alternately generated on both sides of the cylinder. The vortices are continuously generated and separated, and two rows of staggered vortices are formed downstream of the cylinder, which is a "vortex street". ".

Theoretical analysis and experiments have proven that the frequency of vortex separation is directly proportional to the flow rate of the column side medium. The vortices are staggered and separated, generating pulsating pressure in the wake on both sides of the cylinder and behind the cylinder. The detection probe located inside (or behind) the cylinder is affected by this tiny pulsating pressure, causing the detector embedded in the probe to The piezoelectric crystal element is subjected to alternating stress and generates alternating charge signals.

After the signal is transformed, amplified, filtered, amplitude-limited and triggered by the charge on the amplifier, a square wave voltage pulse signal with the same frequency as the vortex separation frequency is output. The signal is then sent to the local display instrument, and each pulse output by the sensor will represent a certain volume of the measured fluid. The total number of output pulses within a period of time will represent the total volume of fluid flowing through the sensor during that period of time. The voltage pulse signal output by the compressed air flow meter sensor is sent to an integrated local display. The compressed air flow meter local display uses the latest micro-power consumption CPU to measure the frequency signal output by the vortex sensor. According to the set density , the vortex flow coefficient is used for flow calculation, and the on-site LCD displays the instantaneous flow and accumulated flow.

How to select a compressed air flow meter

The instrument diameter and specifications of the compressed air flow meter should be selected according to the following principles:

1. Clear the name of the fluid, components.

2. Clarify the maximum, common and minimum flow rates of the working status.

3. Clarify the maximum, commonly used and minimum working pressure and working temperature.

4. The viscosity of the medium under working conditions.

5. Calculate and select the instrument flow range and caliber size according to the different states of the fluid to be measured (liquid, gas, steam).

?