Industry new

General electromagnetic flowmeter installation method and use method introduction

In order to make the electromagnetic flowmeter work stably and reliably, the following aspects should be noted when selecting the installation location:

1. Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields (large motors, large transformers, etc.) to prevent the magnetic field from affecting the working magnetic field and flow signal of the sensor.

2. It should be installed in a dry and ventilated place to avoid sun and rain. The ambient temperature should be -20 ~ +60 °C, and the relative humidity is less than 85%.

3. There should be plenty of space around the flowmeter for easy installation and maintenance.

First, the installation recommendations:

The measurement principle of the electromagnetic flowmeter does not depend on the characteristics of the flow. If there is a certain turbulence and vortex in the pipeline, it will be generated in the non-measurement zone (such as elbow, tangential current limit or half-opening shut-off valve upstream). Nothing. If steady-state eddy currents in the measurement zone will affect the stability of the measurement and the accuracy of the measurement, then some measures should be taken to stabilize the flow rate distribution:

a. increase the length of the straight pipe section before and after;

b. using a flow stabilizer;

c. Reduce the cross section of the measuring point.

1, horizontal and vertical installation

The sensor can be mounted horizontally and vertically, but it should be ensured that the effects of deposits and bubbles on the measuring electrode are avoided and the axial orientation of the electrode is kept good. When installed vertically, the fluid should flow from bottom to top.

The sensor cannot be installed in the highest position of the pipe, which is easy to accumulate air bubbles.

2, ensure full pipe installation

Make sure that the flow sensor is full of the fluid under test when measuring, and that the non-full tube state cannot occur. If the pipe is not full or the outlet is vented, the sensor should be mounted on a siphon.

3. Installation between elbows, valves and pumps

In order to ensure the stability of the measurement, a straight pipe section should be provided before and after the sensor, and the length is given by the following figure. If this is not possible, a stabilizer should be used or the cross-sectional area of the measuring point should be reduced.

4, the sensor can not be installed in the pump inlet

To avoid negative pressure, the sensor should not be installed in the pump's water inlet, but should be installed in the pump's water outlet.

5, the inlet of the sensor straight pipe section and the outlet straight pipe section

For an ideal installation location, there should be enough straight pipe sections before and after the measurement point. The straight pipe section of the inlet should be ≥ 5D, and the straight pipe section of 3 ports should be ≥ 3D (D is the nominal diameter of the sensor). The plug-in inlet straight pipe section should be ≥ 20 D and the outlet straight pipe section ≥ 7D (D is the sensor nominal diameter).

6, the pipe outlet is installed when venting

When the outlet is vented, the sensor should not be installed where the pipe is vented and should be installed at a lower location. When the sensor is installed under the pipe, the sensor should be filled with liquid and the empty pipe state should not occur.

7, series installation and parallel installation

If there are several sensors that need to be connected in series on the same pipe, the distance between each sensor should be at least 2 sensors. If more than two sensors are installed in parallel with each other, the distance of the sensor must be greater than 1 m.

8, the grounding measures of the sensor

The flow signal generated by the sensor is very small, and only a few millivolts at full scale, so the sensor ground should be good. There are two aspects to the grounding requirements of an electromagnetic flowmeter:

From the working principle of the electromagnetic flowmeter and the loop of the flow sensing signal current, the ground of the sensor and the converter must be at the same potential as the measured medium.

2. Ground. With zero ground potential, reduce external interference. In general, the process pipes are all metal pipes, which are all grounded, which is easy to meet. However, in the case of large external electromagnetic field interference, the electromagnetic flowmeter should be separately provided with a grounding device. The grounding wire should be a multi-strand copper wire with a cross-section larger than 5mm2. The grounding wire of the sensor must not be connected to the common ground of the motor or other equipment. To avoid the effects of leakage current. The grounding resistance should be less than 10 Ω.

a. The sensor is mounted on a metal pipe (the inner wall of the metal pipe is not insulated) and is grounded as shown below.

b. The sensor is mounted on a plastic pipe or on an insulated lining. Both ends of the sensor should be fitted with a grounding ring, or a grounding flange, or a short tube with a grounding electrode, grounded as shown below. The measured medium flowing in the tube is short-circuited to the ground, and has a zero potential. Otherwise, the electromagnetic flowmeter cannot work normally.

PREVIOUS：Description of the main points in the installNEXT：Electromagnetic flowmeter batch (quantitative