Accuracy class and function According to the measurement requirements and the use occasions, the instrument accuracy level is selected to achieve economical efficiency. For example, in the case of trade settlement, product handover and energy measurement, the accuracy level should be higher, such as 1.0, 0.5, or higher; for process control, select different accuracy levels according to control requirements; It is to detect the process flow, no need to do precise control and measurement, you can choose a lower accuracy level, such as 1.5, 2.5, or even 4.0, then you can use a low-cost plug-in electromagnetic flowmeter.
Measuring medium flow rate, meter range and diameter When measuring general medium, the full flow of electromagnetic flowmeter can be selected within the range of 0.5-12m/s of measuring medium flow, and the range is wider. The meter specification (caliber) is not necessarily the same as the process pipeline. It should be determined whether the measured flow range is within the flow rate range. That is, when the pipeline flow rate is too low to meet the flow meter requirements or the measurement accuracy cannot be guaranteed at this flow rate, It is necessary to reduce the gauge diameter, thereby increasing the flow rate inside the tube and obtaining satisfactory measurement results.
Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields to prevent the magnetic field from affecting the working magnetic field and flow signal of the sensor.
Should be installed in the dry and ventilated place, to avoid sun and rain, the ambient temperature should be -20 ~ +60 ° C, relative humidity is less than 85%.
There should be ample space around the flowmeter for easy testing and maintenance.
Vortex flowmeter analysis and solution
Summarizing the main causes of these problems, mainly related to the following aspects:
1. Problems with selection. Some vortex sensors are selected on the caliber selection or after the design selection, due to the change of process conditions, so that the selection is larger, the actual selection should be as small as possible to improve the measurement accuracy. The main reason for this is the same. Questions 1, 3, and 6 are related. For example, a vortex pipeline is designed for use by several equipment. Because some of the equipment is not used, the actual actual flow is reduced. The actual design results in too large an original design, which is equivalent to an increase in measurable flow. The lower limit, when the process pipe has a small flow rate, the indication cannot be guaranteed. When the flow rate is large, it can be used, because it is sometimes too difficult to re-engineer. Changes in process conditions are only temporary. The re-tuning of the parameters can be combined to improve the indication accuracy.
2. Installation problems. The main reason is that the length of the straight pipe in front of the sensor is not enough, which affects the measurement accuracy. The reason for this is mainly related to the problem 1. For example, the straight pipe section in front of the sensor is obviously insufficient. Since the FIC203 is not used for measurement, it is only used for control, so the current accuracy can be used equivalent to the downgrade.
The ultrasonic flowmeter is designed based on the geometrical principle that the velocity of the ultrasonic wave propagating in the flowing medium is equal to the average flow velocity of the measured medium and the velocity of the acoustic wave itself. It is also measured by the flow rate to reflect the flow rate. Although the ultrasonic flowmeter appeared only in the 1970s, it is very popular because it can be made into a non-contact type and can be connected to the ultrasonic water level gauge for opening flow measurement without disturbing or resisting the fluid. There are promising flow meters.
Ultrasonic Doppler flowmeters fabricated using the Doppler effect have received widespread attention in recent years and are considered to be ideal gauges for non-contact measurement of two-phase flow.
Fluid oscillating flowmeter
The fluid oscillating flowmeter is designed based on the principle that the fluid will oscillate when flowing under specific flow conditions, and the frequency of the oscillation is proportional to the flow velocity. When the flow cross section is constant, the flow rate is proportional to the flow volume of the pilot volume. Therefore, the flow rate can be measured by measuring the oscillation frequency. This flowmeter was developed and developed in the 1970s. Because it combines the advantages of non-rotating components and pulsed digital output, it has a promising future. At present, typical products include vortex flowmeters and spiral vortex flowmeters.