Electromagnetic flowmeter downtime maintenance and maintenance methods

Case introduction

Maintenance and maintenance methods of the electromagnetic flowmeter when it is shut down:

When the electromagnetic flowmeter is shut down and not in use, we must adopt scientific and reasonable maintenance and maintenance methods for the electromagnetic flowmeter. When providing electromagnetic flowmeter technical services to users, it is often encountered that after users purchase the electromagnetic flowmeter and use it for a period of time, they find that the measurement data is inaccurate when they use it again. In fact, this is not a quality problem with the electromagnetic flowmeter itself. Because the user did not follow the after-use care and maintenance methods in the instruction manual.

1. Regularly check the electrical performance of the sensor during electromagnetic flowmeter maintenance:

First, roughly measure the electrical resistance. Disconnect the signal connection between the sensor and the converter. The sensor is filled with liquid. Use a multimeter to measure the resistance values ​​of the two electrical and ground terminals to see if they are within the value range specified by the manufacturer, and the two measured values ​​are roughly the same.

Record the measured resistance value. This value will be useful for later determining the cause of sensor failure (such as whether the deposited layer is conductive or insulating).

Secondly, drain the liquid out of the sensor, wipe the inner wall, and after it is dry, use a megger to measure the resistance between the two electrical and ground terminals.

After that, check the insulating resistance of the excitation coil, remove the sensor excitation coil, connect the terminals to the converter, and measure the insulating resistance of the coil with a megohmmeter.

2. Electromagnetic flow Zero point inspection and adjustment for meter maintenance:

Before the electromagnetic flowmeter is put into operation, the zero point must be adjusted when the electromagnetic flow sensor is filled with liquid and is stationary after power is turned on. After being put into operation, it is also necessary to periodically stop the flow and conduct zero-point inspections according to the operating conditions; especially for non-cleaning fluids that are precipitated, easy to pollute electricity, and contain solid phases, more inspections should be made in the early stages of operation to gain experience and determine the normal inspection cycle. The electromagnetic flowmeter with AC excitation method is more likely to produce zero point drift than the rectangular wave shock ratio, so more attention should be paid to inspection and adjustment.

Give two examples of application errors that caused failure of the deposition layer. One is that in oil drilling and cementing projects, the total flow volume of cement slurry is an important process parameter, and high-pressure electromagnetic flowmeters are often used. The instrument is used intermittently. After use, rinse the sensor measuring tube with clean water and leave it empty the rest of the time. Due to improper cleaning, the residual cement slurry on the inner wall of the measuring tube solidified into a thin layer. In the past two months, it accumulated to form an edge layer, covering the entire electrical surface, resulting in abnormal operation and eventually failure to work.