Is the pressure measurement point of a clamp-on vortex flowmeter selected before or after the meter?

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In order to reduce measurement errors, whether it is a wafer-type vortex flowmeter or other types of vortex flowmeters, the pressure measurement point should be selected after the table.

From the working principle of the vortex flowmeter, it can be known that the vortex stripping frequency is proportional to the average flow speed downstream of the vortex generator, as shown in Figure 1, that is, the output frequency of the vortex flowmeter represents the vortex generator volume flow rate at.

When the measured fluid is a gas, the volume flow rate under working conditions must be converted to the standard state volume flow rate. When the measured fluid is steam, it is required to obtain the fluid density corresponding to the volume flow rate and to know the fluid pressure under the working conditions. Due to the compressibility of gas and steam, when the fluid flows in the pipeline, the static pressure of the fluid is also different on different sections, so a question arises as to where the pressure measuring port should be reasonably located.

Since the volume flow rate is the volume flow rate downstream of the vortex generator, the pressure measuring port should also be opened on the pipe wall here. However, there is no pressure measuring port on the meter body of the vortex flow sensor, so the pressure measuring port can only be opened on the pipeline downstream of the flow meter. From a principle analysis, the pressure measured in this way is higher than the pressure where the vortex is generated, but for a flow meter with an accuracy level of 0.75% to 1.5%, the error caused by this simplification can be ignored.

If the pressure measuring port is opened upstream of the vortex flowmeter, the measured pressure will be much higher than downstream. Because when the fluid flows through the vortex generator, a pressure drop occurs before and after the generator. Therefore, when measuring fluid pressure, the pressure point should be taken downstream of the vortex flow sensor.

Supmea Measurement and Control has been engaged in the production, R&D and sales of vortex flowmeters for many years. Its main business includes vortex flowmeters, balance/orifice flowmeters, electromagnetic flowmeters & heat meters, and ultrasonic flowmeters. & Heat meter, mass flow meter, prepaid totalizer, intelligent flow totalizer, intelligent heat totalizer, prepaid metering terminal, data acquisition terminal, pressure transmitter, differential pressure transmitter, temperature sensor, electric Valve, steam prepayment management system, smart heating network management system, smart heating management system, smart gas management system, smart water management system and comprehensive energy management system.