Germany E + H electromagnetic flowmeter installation and commissioning

(1) The application of electromagnetic flowmeter has certain limitations. It can only measure the liquid flow of conductive media, not the liquid flow rate of conductive media. Flows of non-conductive media such as gases and water are better treated for heating water. In addition, its lining needs to be considered under high temperature conditions. (2) The electromagnetic flowmeter determines the volume flow rate under working conditions by measuring the speed of conductive liquid. According to the measurement requirements, for liquid media, the mass flow rate should be measured, and measuring the medium flow rate should involve the density of the fluid. Different fluid media have different densities, and they change with temperature. If the electromagnetic flowmeter converter does not consider the fluid density, it is inappropriate to only give the volume flow rate at room temperature. (3) The installation and debugging of electromagnetic flowmeters are more complicated than other flowmeters, and the requirements are more stringent. The transmitter and converter must be used together, and two different types of instruments cannot be used together. When installing the transmitter, from the selection of the installation location to the specific installation and debugging, the product instructions must be strictly followed. There should be no vibration or strong magnetic field in the installation location. During installation, the transmitter and pipeline must have good contact and good grounding. The potential of the transmitter is the same as that of the fluid being measured. During use, the gas remaining in the measuring tube must be exhausted, otherwise it will cause large measurement errors. (4) When the electromagnetic flowmeter is used to measure viscous liquids with dirt, the sticky matter or sediment adheres to the inner wall of the measuring tube or the electrode, causing the output potential of the transmitter to change, causing measurement errors. The dirt on the electrode reaches a certain level. Thickness may cause the meter to be unable to measure. (5) Scale or wear of the water supply pipeline changes the inner diameter, which will affect the original flow value and cause measurement errors. For example, a 1mm change in the inner diameter of a 100mm diameter instrument will bring about an additional error of approximately 2%. (6) The measurement signal of the transmitter is a very small millivolt level potential signal. In addition to the flow signal, it also contains some signals that have nothing to do with the flow, such as phase voltage, quadrature voltage and common mode voltage. In order to accurately measure flow, it is necessary to eliminate various interference signals and effectively amplify the flow signal. The performance of the flow converter should be improved. It is best to use a microprocessor-based converter. Use it to control the excitation voltage. Select the excitation mode and frequency according to the properties of the fluid being measured, which can eliminate in-phase interference and orthogonal interference. However, the improved instrument structure is complex and the cost is high. (7) Higher price ultrasonic flowmeter 1. Advantages (1) Ultrasonic flowmeter is a non-contact measuring instrument that can be used to measure fluid flow and large pipe diameter flow that are not easy to contact or observe. It does not change the flow state of the fluid, does not produce pressure loss, and is easy to install. (2) It can measure the flow of highly corrosive media and non-conductive media. (3) The ultrasonic flowmeter has a large measurement range, with the pipe diameter ranging from 20mm to 5m. (4) The ultrasonic flowmeter can measure various liquid and sewage flows. (5) The volume flow measured by the ultrasonic flowmeter is not affected by thermal physical parameters such as temperature, pressure, viscosity and density of the fluid being measured. Can be made into two forms: fixed and portable. 2. Disadvantages (1) Ultrasonic flowThe temperature measurement range of the meter is not high, and it can generally only measure fluids with temperatures below 200°C. (2) Poor anti-interference ability. It is susceptible to interference from bubbles, scaling, ultrasonic noise from pumps and other sound sources, and affects measurement accuracy. (3) The straight pipe section has strict requirements, which is 20D in the front and 5D in the back. Otherwise, the discreteness will be poor and the measurement accuracy will be low. (4) Installation uncertainty will bring large errors to flow measurement. (5) Scale in the measurement pipeline will seriously affect the measurement accuracy and bring significant measurement errors. In severe cases, the meter may even have no flow display. (6) The reliability and accuracy level are not high (generally around level 1.5 to 2.5), and the repeatability is poor. (7) Short service life (general accuracy can only be guaranteed for one year). (8) The ultrasonic flow meter determines the volume flow rate by measuring the fluid velocity. For liquids, its mass flow rate should be measured. The mass flow rate measured by the instrument is obtained by multiplying the volume flow rate by the artificially set density. When the fluid temperature changes, The fluid density changes, and artificially setting the density value cannot guarantee the accuracy of the mass flow rate. Only by measuring the fluid velocity and measuring the fluid density at the same time can the true mass flow value be obtained through calculation. (9) The price is higher. E+H vortex flowmeter 1. Advantages (1) The vortex flowmeter has no moving parts, the measuring element has a simple structure, reliable performance and long service life. (2) The vortex flowmeter has a wide measuring range. The range ratio can generally reach 1:10. (3) The volume flow rate of the vortex flowmeter is not affected by thermal parameters such as temperature, pressure, density or viscosity of the fluid being measured. Generally no separate calibration is required. It can measure the flow of liquid, gas or steam. (4) It causes small pressure loss. (5) The accuracy is high, the repeatability is 0.5%, and the maintenance is small. 2. Disadvantages (1) The volume flow rate of the vortex flowmeter under working conditions is not affected by thermal parameters such as temperature, pressure, and density of the measured fluid, but