Electromagneticflowmeters are the commonly used measuring instruments in sewage treatment andchemical engineering industry. Many friends may encounter a variety ofproblems: unstable flow values, inaccurate flowmeters, and frequent flowmeterdamage. So how to solve them?
Theaccurate selection is very important,butmore importantly are the wrong installation ways of the electromagneticflowmeters
Problem1: Large fluctuations with flow rate
At acertain site, the value of the customer’s electromagnetic flow meter has been fluctuating.
Caseanalysis
Atthe site there is a pump next to the flow meter. The fluid is in a turbulentstate (that is, the water swirls) when passing through the flowmeter. In thiscase, the flowmeter is subject to greater disturbance during measurement, andthen occurs the phenomenon.
Solution
Wheninstalling the electromagnetic flowmeter, keep it away from the pump and atleast 5 times the distance from the straight pipe section to ensure fluidstability.
A similar case installed near the valve▼
Problem2: The flow rate is always inaccurate.
Onthe customer site, flow measurement is always inaccurate, and sometimes therewill be empty pipe alarm and lower limit alarm.
Caseanalysis
Fromthe above image, we can see that only half of the pipe is less than water,which means that the electromagnetic flowmeter is not full at all. How can thisbe measured accurately?
Solution
Atthe outlet of the flowmeter, install a section of the pipe to extend it andreduce the diameter so that the liquid fills the entire pipe.
Problem3: The electromagnetic flowmeter is often damaged
Caseanalysis
Thiselectromagnetic flowmeter is installed under the water, and the instruments maycause the damage. Generally, the enclosure of the electromagnetic flowmeter isIP65, it can support rain protection, and cannot be soaked.
Solution
itis recommended to use the IP68 protection class. If the on-site pipe does notsupport reducing the diameter, the sewage can be concentrated and then the pipecan be re-plied. After the pump is used, the flowmeter is installed. Or changeto ultrasonic open channel flow meter.
Whyis electromagnetic flowmeter measurement so strict on installationrequirements?
1. Theelectromagnetic flowmeter measurement principle is mainly based on Faraday’selectromagnetic induction principle. The conductive medium cuts the magneticinduction wire to generate the induced electromotive force, and the twomeasuring electrodes installed on the central axis of the pipeline collect thesignal.
Let’s look at the analysisof the first case. The measured water may not have passed through the measuringelectrode, and no signal is completely sensed. The flow meter naturallydisplays a lower limit alarm or an empty tube alarm. So, the it must need the fullwater of the pipe.
Under whatcircumstances can water guarantee full pipe?
Vertical pipes,water from bottom to top, certainly full of friends, of course, there is also ahorizontal pipe installation method. So that the flow of the pipe in theselected range, the flow is certainly accurate and stable.
2. The flowthrough the flowmeter in the pipeline should be uniform and stable. Because wemeasure the flow, which is actually the product of the flow rate and thecross-sectional area of the pipe. The flow rate is unstable and the flow will naturally jump.
Let’s look the analysisof the second case, the pump is near the flow meter, the first to rule outhigh-power instrument interference with the product signal, the flow rate iscertainly unstable, so our conventional choice is to install the flow meter asfar as possible. Of course, one of the most important things, a long straight pipeis needed!
The role of thestraight section is to smooth the flow rate of the fluid so that it can flowevenly and stably through the flowmeter. Then continue to read with me,straight into the paragraph, the first ten five, the first ten five. (It meansthat the flowmeter must have 10 times the straight pipe section in the upstreamdirection and 5 times the straight pipe section in the downstream)
Sichuan VacordaInstruments Manufacturing Co., Ltd
21 Years FocusedonLevel MeasurementinExtremeProcessConditions
Tel: +86 28 87013699
Email: sales@vacorda.com
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Post time: 21-09-21