High precision measurement:
Electromagnetic flowmeters work based on Faraday’s law of electromagnetic induction. When a conductive liquid (both sewage and water have a certain conductivity) flows in a magnetic field, an induced electromotive force is generated, and its size is proportional to the flow rate of the liquid. In the practical application of sewage and water plants, this measurement method can provide high precision flow data. For example, in the chemical dosing process of sewage treatment, accurate flow measurement can ensure that the chemical and sewage are mixed in the right proportion to achieve the best sewage treatment effect.
Free flow parts:
The electromagnetic flow meter has no internal components that hinder the flow of fluid, such as raw water containing sediment, algae and other impurities in the water plant, and the composition of the sewage is complex, which may contain solid particles, fibers and other substances. The electromagnetic flowmeter will not be blocked because of these impurities, which can ensure the smooth passage of the fluid, reducing the maintenance cost of the equipment and the measurement error caused by congestion.
Wide range ratio:
You can measure a flow rate range from very low to very high. In the water supply system of the water plant, the water consumption of different periods varies greatly, such as the peak period of water use during the day and the trough period at night, the electromagnetic flowmeter can accurately measure the water quantity under different flows and adapt to the change of water supply flow. In the sewage plant, the sewage flow at different stages of treatment will also have great changes, and the electromagnetic flowmeter can also effectively deal with it.
Bidirectional measurement capability:
In some sewage and water treatment processes, fluids may flow in reverse. For example, in some circulating systems or pumping stations in sewage treatment plants, water flow reversal may occur during equipment commissioning or troubleshooting. Electromagnetic flowmeters can accurately measure forward and reverse flow, providing comprehensive data for system operation and monitoring.
Installation points
Location selection:
In order to ensure the accuracy of the measurement, the electromagnetic flowmeter should be installed in the pipeline where the fluid flow state is stable. In the pipeline system of sewage and water plants, it is necessary to avoid installation near local resistance parts such as elbows and tees of pipelines. For example, if the electromagnetic flowmeter is installed very close to the downstream position of the elbow in the sludge conveying pipeline of the sewage plant, the measurement error will be caused by the vortex and uneven flow velocity distribution of the fluid at the elbow. The ideal installation position is in the straight pipe section, the length of the upstream straight pipe section is generally recommended to be 5-10 times the pipe diameter, and the length of the downstream straight pipe section is generally 3-5 times the pipe diameter.
Grounding requirements:
Good grounding is an important condition for the normal operation of electromagnetic flowmeters. Because the electromagnetic flowmeter is based on the principle of electromagnetic induction, accurate signal detection requires appropriate grounding. In the environment of sewage and water plants, because there may be more electrical equipment and interference sources around, pay more attention to grounding. In general, the sensor housing of the electromagnetic flowmeter should be grounded separately, and the grounding resistance should be less than 10Ω. If the pipe is made of metal, the pipe can also be used as part of the grounding, but make sure that the grounding connection of the pipe is good.
Full tube requirements:
Electromagnetic flowmeters require the fluid in the pipe to be in a full tube state. In the sewage lifting pump station of the sewage plant, it is necessary to ensure that the selection and operation parameters of the sewage pump are appropriate, so that the sewage can flow in the pipeline. If there is gas in the pipeline, it will affect the magnetic field distribution and induced electromotive force generation, resulting in inaccurate measurement. For the water supply pipeline of the water plant, in the process of starting and stopping the water supply, attention should also be paid to prevent air from entering the pipeline to ensure the normal full tube measurement of the electromagnetic flowmeter.
Maintenance precautions
Check the electrodes regularly:
Electrode is the key component of electromagnetic flowmeter. In the environment of sewage and water plants, the electrode surface may be covered by impurities in the water, such as oil and scale in sewage. Regular cleaning of the electrode ensures the accuracy of the measurement. Generally, the method of chemical cleaning can be used to select the appropriate cleaning agent according to the dirt composition of the electrode surface. For example, if the electrode surface is mainly calcium carbonate scale, you can use dilute hydrochloric acid solution for cleaning, but pay attention to rinse with water after cleaning to avoid the residual cleaning agent on the electrode and fluid.
Check lining condition:
The lining of the electromagnetic flowmeter can protect the sensor body, but also has a certain impact on the measurement accuracy. In the long-term operation of sewage and water plants, the lining may be washed and corroded by fluids. For example, when sewage plants treat industrial sewage containing strong acidity or alkalescence, the lining may be corroded. It is necessary to regularly check whether the lining is damaged, aging, etc., and replace the lining in time to ensure the normal operation of the flow meter.
Signal line check:
The signal line of the electromagnetic flowmeter transmits the measurement signal, and in the complex industrial environment of sewage and water plants, the signal line may be subject to electromagnetic interference, moisture and so on. Regularly check whether the connection of the signal line is firm, whether there is damage and so on. If the signal line is found to have interference problems, measures such as shielding cables can be used to enhance the stability of signal transmission.
Post time: Nov-05-2024