Electromagnetic flowmeter installation considerations

Electromagnetic flowmeter is widely used in chemical, petroleum, medical, sewage treatment and other industries as a common instrument for measuring conductive liquid medium. Tiankang Instrument has many years of experience in the production of electromagnetic flowmeters, and first talked about the installation of electromagnetic flow sensors.

First, the sensor installed in the pipeline When selecting the sensor installation location on the process pipeline, you should pay attention to:

(1) It must be ensured that the sensor measuring tube is always filled with the measured fluid at all times, and the sensor cannot work under the condition that the tube is not full and there is a possibility of empty tube;

(2) The flow direction of the fluid in the sensor must be consistent with the flow direction on the sensor;

(3) When measuring two-phase fluids, choose a place that is not likely to cause phase separation;

(4) The sensor should select the location where the fluid pulsation in the tube is smaller as the measurement point. Under normal circumstances, the meter indication is relatively stable and less fluctuating from places far away from pumps, valves, etc.

(5) Avoid places where liquid conductivity is not easily generated. For example, the conductivity of the additive liquid is different from that of the base liquid. The liquid addition point is preferably located downstream of the sensor.

(6) For Teflon-lined sensors, avoid installation in negative pressure piping and areas where transient negative pressure may occur.

Second, the straight pipe length requirements According to the classical theory, when the sensor measurement tube velocity distribution is axisymmetric, the electromagnetic flowmeter measurement accuracy is not affected by the flow velocity distribution.

Small-diameter sensors and some medium-caliber sensors have a distance (L) from the center of the electrode to the inlet end of the measuring tube that is equivalent to several times the diameter (D) of the straight tube section, so that even if the fluid flow in front of the sensor inlet end is non-axisymmetric, the measurement is also performed. It will not be affected. However, as the diameter of the instrument increases and the sensor structure improves, the L/D value becomes smaller and smaller, and the straight pipe section formed by the sensor measuring tube itself is not enough to "symmetry" the non-axisymmetric flow.

The bends and valves in the process pipeline can cause flow distortion, secondary flow or vortices, and destroy the fully developed flow velocity distribution. To allow the fluid to recover its axisymmetric flow velocity distribution, a fairly straight length of tubing is required, or a flow regulator is placed in front of the flow sensor. Therefore, the electromagnetic flow sensor has the requirement of straightening the upstream pipe section.

The lengths of the upstream and downstream straight pipes proposed by various standards or verification regulations are also inconsistent. Most of them are higher than those required by normal instrument manufacturers. This is to ensure that the instrument meets the requirements of a class 0.5 accuracy meter.

Tiankang electromagnetic flow meter to meet customer needs first, quality first, allowing customers to use the rest assured. The reputation of Wuhan electromagnetic flow meter in the industry and customer feedback are all satisfactory: high precision, durability, long service life, low failure rate, and good after-sales service. Your satisfaction is the driving force of our progress. Efforts are made to develop new technologies, improve product performance, use high-quality materials, and meticulously adhere to the quality of products, and ensure the passing rate of production testing is 100%.

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