﻿ flowmeter counter electromagnetic

# flowmeter counter electromagnetic

2019-10-22 09:42:48

## flowmeter counter electromagnetic

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.

## flowmeter counter electromagnetic

Vortex flowmeter working principle
The working principle of the vortex flowmeter is to arrange a vortex generator in the fluid, so that the vortex is alternately generated on both sides of the body, and the vortex column is asymmetrically arranged downstream of the vortex generator to generate a certain frequency, by the formula f= St*v/(1-1.27d/D)*d, (St is the Strauhal number, which is a dimensionless number, related to the vortex generator and Reynolds number; v is the flow velocity; d is the incident head width; D is the nominal diameter) to get the flow rate.
In general, the vortex flowmeter output signal (frequency) is not affected by changes in fluid properties and composition, which means that the meter factor is only related to the shape and size of the vortex generator and the Reynolds number. Its advantages are: simple and firm structure, convenient installation and maintenance; suitable for a variety of fluids, liquid, gas, steam and some mixed phases are applicable; high precision, generally up to ± 1% R; flow range is wide, up to 10 : 1 or 20:1 or more; low head loss; no zero drift; relatively cheap price; disadvantage: not suitable for low Reynolds number Re <20000, limited use of high viscosity, low flow rate, small diameter The requirements for the environment are high, and places with vibration should be eliminated as much as possible, and the upstream side needs to have a long straight pipe section; the meter factor is lower, and the larger the diameter, the lower the diameter. The signal resolution is reduced, so the aperture should not be too large, generally used in DN15~DN300mm.

## flowmeter counter electromagnetic

Precautions
The correct selection of ultrasonic flowmeters can ensure better use of ultrasonic flowmeters. The type of ultrasonic flowmeter to be selected should be determined according to the physical properties and chemical properties of the fluid medium to be tested, so that the diameter, flow range, lining material, electrode material and output current of the ultrasonic flowmeter can be adapted to the properties of the fluid to be measured. And flow measurement requirements.
1, precision function check
Accuracy levels and functions are based on measurement requirements and usage scenarios to select instrument accuracy levels for cost-effectiveness. 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 ultrasonic flowmeter.
2, measurable medium
Measuring medium flow rate, meter range and caliber When measuring a general medium, the full flow rate of the ultrasonic flow meter can be selected within the range of 0.5-12 m/s of the measured medium flow rate, and the range is relatively wide. The selection of the meter specification (caliber) is not necessarily the same as the process piping. It should be determined according to whether the measured flow range is within the flow rate range. That is, when the pipeline flow rate is too low to meet the requirements of the flow meter or the measurement accuracy is not 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.