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Analysis of advantages and disadvantages of sewage flowmeter application
Jan 02, 2019


Analysis of advantages and disadvantages of sewage flowmeter application


The process of purifying sewage to meet the water quality requirements for discharge into a certain water body or reuse. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, catering and other fields, and more and more into the daily lives of ordinary people. Sewage treatment is also a very important aspect. In the sewage treatment, a very important instrument-flow meter will be needed, which is called sewage flow meter!

   So what is the sewage flow meter? In general, the largest choice for sewage measurement is the sewage flow meter. The sewage flow meter is based on Faraday's law of electromagnetic induction, and the volume of the conductive medium in the measuring tube is used to calculate the volume of the flow. Huaheng Instrument briefly explains the advantages and disadvantages of the sewage flow meter here.

 

Analysis of advantages and disadvantages of sewage flowmeter application

Advantages of sewage flow meter:

   1. The sensor of Huaheng Instrument's sewage flowmeter has a simple structure. There are no moving parts in the measuring tube, and there are no throttling parts that hinder the fluid flow. Therefore, when the fluid passes through the flowmeter, it does not cause any additional pressure loss, and is one of the flow meters with the lowest energy consumption in the flowmeter.

   2. It can measure the flow rate of smear medium, corrosive medium and suspended liquid-solid two-phase flow. This is due to the fact that there is no obstructive flow component inside the metering tube. Only the measuring tube lining and the electrode are in contact with the fluid to be measured, and the material can be selected according to the nature of the fluid to be measured. There are many choices for lining, such as PTFE, polyfluoroethylene, neoprene, and urethane rubber. The choice of the electrode of the sewage flow meter is: stainless steel electrode, ha B electrode, ha C electrode, tantalum electrode, titanium electrode and the like. These will be selected based on the composition of the sewage.

   3. The sewage flow meter is a volume flow measuring instrument. During the measurement process, it is not affected by the temperature, viscosity and density of the measured medium. Therefore, the sewage flow meter can be used to measure the flow rate of other conductive liquids only after being calibrated by water. Unless the conductivity is not met, the liquid conductivity measured by the sewage flow meter must be greater than 5 μS/cm.

   4. The output of the sewage flow meter is only proportional to the average flow velocity of the measured medium, and is independent of the flow state under the symmetric distribution. Therefore, the electromagnetic flowmeter has an extremely wide measuring range and its measuring range is up to 100:1.

   5, no mechanical inertia, responsive, can measure instantaneous pulsating flow.

   6. The scope of the industrial sewage flowmeter is extremely wide, ranging from a few millimeters to several meters, and the domestic real-flow calibration equipment with a diameter of 3m has laid the foundation for the application and development of the sewage flowmeter. Sewage flowmeters are also extremely accurate, typically at level 0.5.

   

Analysis of advantages and disadvantages of sewage flowmeter application

Disadvantages of sewage flow meters:

    a. The application of the sewage flow meter has certain limitations. It can only measure the liquid flow rate of the conductive medium, and cannot measure the flow rate of the non-conductive medium, such as gas and water for better heat treatment. In addition, the lining needs to be considered under high temperature conditions.

    b. The sewage flow meter determines the volume flow rate under working conditions by measuring the speed of the conductive liquid. According to the measurement requirements, for liquid media, mass flow should be measured. The flow rate of the medium should be related to the density of the fluid. Different fluid media have different densities and vary with temperature. If the electromagnetic flowmeter converter does not consider the fluid density, it is not appropriate to give only the volume flow at normal temperature.

    c. The installation and commissioning of thebis more complicated than other flow meters, and the requirements are more stringent. The transmitter and converter must be used together and cannot be used with two different types of instruments. When installing the transmitter, the selection from the installation site to the specific installation and commissioning must be carried out in strict accordance with the product specifications. The installation site must be free from vibration and strong magnetic fields. The transmitter and piping must be in good contact and well grounded during installation. The potential of the transmitter is equipotential to the fluid being measured. When using, the gas remaining in the measuring tube must be drained, otherwise it will cause a large measurement error.

    d. When the electromagnetic flowmeter is used to measure the viscous liquid with dirt, the sticky substance or the precipitate adheres to the inner wall or the electrode of the measuring tube, so that the output potential of the transmitter changes, which brings measurement error, and the dirt on the electrode reaches a certain thickness. , may cause the meter to be unable to measure.

    e. Fouling or wear of the water supply pipe changes the inner diameter size, which will affect the original flow value and cause measurement error. If the inner diameter of the 100mm diameter meter changes by 1mm, it will bring about 2% additional error.

    f. The transmitter's measurement signal is a small millivolt potential signal. In addition to the flow signal, it also contains some flow-independent signals, such as phase voltage, quadrature voltage and common mode voltage. In order to accurately measure the flow rate, various interference signals must be eliminated to effectively amplify the flow signal. Should improve the performance of the flow converter, Zui is good to use the microprocessor type converter, use it to control the excitation voltage, select the excitation mode and frequency according to the nature of the fluid to be tested, can eliminate in-phase interference and quadrature interference. However, the improved instrument structure is complicated and the cost is high.

    g. Sewage flow meter price is higher