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Instrument knowledge|Precautions for installation of electromagnetic flowmeter
Source:Xi’an Dechuang Electrical Technology Co., Ltd. | Author:西安德创电气科技有限公司 | Published:2020-08-06 | Browse: 356 timesClose this page

Instrument knowledge|Precautions for installation of electromagnetic flowmeter

Electromagnetic flowmeters can measure conductive liquids and are widely used in chemical, chemical fiber, food, paper, sugar, mining and metallurgy, urban water supply and drainage, environmental protection, water conservancy, steel, petroleum, pharmaceuticals and other industrial fields to measure various acids , Alkali, salt solution, mud, mineral pulp, paper pulp, coal water slurry, corn steep liquor, fiber pulp, grain pulp, lime milk, sewage, etc.

Electromagnetic flowmeter has a series of excellent characteristics, which can solve the problems that other flowmeters are not easy to use, such as the measurement of dirty flow and corrosive flow.

Advantage

The measurement channel is a smooth straight pipe, which will not be blocked, and is suitable for measuring liquid-solid two-phase fluids containing solid particles, such as pulp, mud, sewage, etc.;

The detection will not cause pressure loss, and the energy saving effect is good;

The measured volume flow is actually not significantly affected by changes in fluid density, viscosity, temperature, pressure and conductivity;

Wide range of turndown ratio and wide caliber range;

Corrosive fluids can be used.

Disadvantage

Cannot be used to measure gas, steam and liquids containing a large amount of gas;

It cannot be used to measure liquid media with very low conductivity, and the electromagnetic flowmeter cannot measure petroleum products or organic solvents and other media;

It cannot be used to measure high temperature media. At present, it is restricted by the lining material and electrical insulation material of the measuring tube of the electromagnetic flowmeter for general industry;Electromagnetic flowmeters are easily affected by external electromagnetic interference.

Installation Precautions

In order to make the electromagnetic flowmeter meet the working conditions of the measurement site and meet the accuracy and function requirements of the instrument, the following precautions are required during the installation process:

1.Install according to the calibration direction

The direction of the arrow on the sensor must be consistent with the actual flow direction. (If the installation is reversed, the flow direction item in the converter menu must be corrected)


2.Ensure that the full pipe is installed

The full tube measurement state must be ensured, and the non-full tube state cannot occur.

Avoid installation upstream of the downward pipeline;

Avoid installing at the highest point of the pipeline, which is easy to collect bubbles


When installing on a horizontal pipeline, the two measuring electrodes should not be directly above and directly below the pipeline. When installed vertically, the fluid should flow from bottom to top.

3 Straight pipe distance requirements

Must ensure that the first 10 and rear 5 straight pipe sections



4 Series and parallel installation

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

5 installation and bypass pipe

The pipeline where the flowmeter is installed should have a valve that can cut off the medium in the pipeline to facilitate daily maintenance and maintenance. When the process does not allow flow interruption. A bypass pipe can be added to the pipe where the flowmeter is installed.

6 Sensor ground

The sensor must be well grounded separately

Grounding meaning:

Give the signal source a reference to zero potential, so that the measured medium is connected to the earth. The safety requirements (such as lightning strikes) are against external interference. The grounding point is as close as possible to the sensor, and it must not be connected to the grounding point of other equipment. Ground resistance 10Ω

Grounding requirements:

Electromagnetic flowmeter transmitter housing, shielded wire, measuring conduit and pipes at both ends of the transmitter must be grounded and set a separate grounding point, and must not be connected to public ground wires or upper and lower pipes such as electric motors; the converter part has passed the cable Line grounding, there is no need to ground again to avoid interference due to different potentials.

Grounding method with grounding ring:

If the process pipeline is made of insulating material, it must be equipped with a grounding ring to stabilize the boundary conditions. Improve the measurement qualitative and accuracy.

7.Ensure that the split type electromagnetic flowmeter is matched and installed

The split type electromagnetic flowmeter should ensure that the electromagnetic flow converter and the sensor are matched with the number, and the number of the converter and the matching sensor is the same (Zhang Guan Li Dai will not work normally)

8.Wire and lay cables correctly

Must be wired and cabled correctly

The connecting cables of the sensor and the converter must be seated in correct numbers and connected correctly (understand the meaning of each line number)

Cable installation precautions: The signal cable and the excitation cable are separated through pipes (iron pipes) to prevent interference and mechanical damage. The special cable provided by the company must be used. The signal cable, excitation cable and power line must be installed separately, and the pulse output line should be considered between the lines. Distributed capacitance should not be too long.

9 .Reasonable configuration of the rear position instrument

The rear instrument of the electromagnetic flowmeter must be reasonably configured

The active or passive output should be determined according to the requirements of the subsequent instrument. The external power supply for passive output should meet the technical specifications. If the resistance is connected in series, the resistance value should be within the allowable range.

10 .proofreading the power supply voltage

The power supply voltage must be calibrated before commissioning (the phenomenon of 24VDC instrument being burned out by 220VAC power supply is endless)

During debugging, only zero position adjustment is allowed, and various parameters are set after factory calibration without any need to change.

 
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