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Typical Wrong Installation Of Electromagnetic Flowmeter

Electromagnetic flowmeter, is widely known instrument in the automation industry. As we all know, for the flowmeter, the model selection is important, but more important is the installation. Today we are going to share the wrong way to install electromagnetic flowmeter.
 
Case 1: Flow fluctuates greatly
A scene, the customer's electromagnetic flow meter value keep beating,

 
Case Analysis:
There is a pump on the spot, and the pump is next to the flow meter. When the fluid passing through the flowmeter, the fluid is in a turbulent state (that is, water whirlpool), this time for the flow meter measurement, there is a large interference, so the flow counting value often keep beating.
 
Solution:
Install flowmeter away from the pump, at least 5D diameter of the straight pipe from the distance to ensure fluid stability.
 
There are similar cases that are installed near the valve

 
Case 2: Flow measurement always inaccurate
A scene, flow measurement always inaccurate and sometimes there will be FGP alarm and FQL alarm.

 
Case Analysis:
From above picture, we only see half of the pipe, that is mean the electromagnetic flowmeter not full of pipe. Flow meter is not full of pipe, how could this be accurate?
 
Solution:
Behind the flow meter exports, can be reduced diameter, the installation of a pipeline extension, so that the liquid filled the entire pipeline.
 
Case 3: Electromagnetic flowmeter is often damaged
Can you see the flowmeter?


We pump away the water to see the well here, flowmeter was flooded for a long time. Generally, electromagnetic flowmeter protection level is IP65 , rain-proof is ok, but soaking in water is not permitted.
 
Case Analysis:
In the situation of soaking in water for a long term, you must choose IP68 protection, can support the water immersion, otherwise the water damage the flowmeter you will loss more.
 
Solution:
It is recommended to use IP65 protection class, if the site pipe does not support to reduce diameter, you can focus on the sewage, and then re-pipe, after pump out to install flowmeter. Or to choose an ultrasonic open channel flowmeter.
 
Why is electromagnetic flowmeter measurement so strict on the installation requirements?
 
1. Electromagnetic flowmeter measurement principle is mainly based on Faraday's electromagnetic induction principle, conductive medium cutting magnetic induction line to generate induced electromotive force, through the central axis of the pipeline to install the two measurement electrodes to collect the signal.
 
So that we should be able to have some analysis of the first case. The measured water may not have been over the measurement of the electrode, completely unable to sense the signal, the flowmeter naturally shows the FQLalarm or even FGP alarm.
 
What kind of circumstances can the water be kept full?
Vertical pipes, water from bottom to top, it is certainly full of pipe, of course, the level of the pipeline is also a way to install. So that the flow of the pipeline as long as the selected range, the flow is certainly accurate and stable.
 
2. The pipeline flow through the flowmeter, the flow rate should be uniform and stable. Why? We measure the flow, actually measuring the flow rate and the cross-sectional area of the product. That flow instability, the flow will naturally beating.
 
Analysis of the second case, pump near the flowmeter, and first exclude high-power equipment on the product signal interference, the flow rate is certainly unstable, so our conventional choice is to install the flowmeter as far as possible. Of course, also need one of the most important things, long enough straight pipe!
 
The function of the straight pipe is to smooth the flow rate of the fluid, allowing it to be evenly and steadily through the flow meter. Straight pipe requirement is before 10D after 5D (Refers to the upstream direction of the flow meter to have 10 times the straight pipe, the downstream to have 5 times the straight pipe)