Magnetic flap liquid level meter is a kind of instrument that can measure and display liquid level directly on the spot. It is convenient to observe and record the measurement results without long-distance signal transmission through dragging cable. At present, the instrument has been widely used in petroleum, chemical industry and other industries.

Magnetic flap liquid level meter, which can display the liquid level on the spot without relying on other electronic devices, has stable and reliable product performance and small fluctuation, so it is widely used in pressure vessels of thermal power plants; such liquid level meter is installed in heat exchangers such as high and low pressure deaerator, raw water heater, heat network heater, high and low pressure heater and condenser of units. It can achieve high sealing, leak proof and suitable for high temperature, high pressure, corrosion-resistant occasions, and the whole process of measurement has no blind area, clear display and large measurement range.

The working medium of heat exchanger is easily vaporized liquid, the pressure is from vacuum state to 2.5MPa, and the temperature is from 40 ℃ to 390 ℃. Therefore, the accuracy of daily maintenance and indication of liquid level gauge plays an important role in the safe operation of pressure vessel.

Working principle of magnetic flap liquid level meter: working according to the principle of buoyancy and magnetic coupling. When the liquid level in the measured container rises and falls, the float in the main tube of the liquid level gauge rises and falls accordingly. The permanent magnetic steel in the float is transmitted to the field indicator through magnetic coupling, driving the red and white turning column 180 °, when the liquid level rises, the turning column turns from white to red, when the liquid level falls, the turning column turns from red to white, and the red and white boundary of the indicator is the actual high liquid level of the medium in the container Degree to achieve liquid level indication.

What factors should be considered in the selection of magnetic flap liquid level meter?

1. Measuring objects, such as the physical and chemical properties of the measured medium, working pressure and temperature, installation conditions, liquid level change speed, etc.

2. Measurement and control requirements, such as measurement range, measurement (or control) accuracy, display mode, field indication, remote indication, interface with computer, safety and corrosion protection, reliability and construction convenience.

3. The demagnetization of magnetic materials should also be considered. Demagnetization may cause the level gauge to fail to work normally and the measurement result may be inaccurate.

Features of magnetic flap liquid level meter:

1. The measurement range is large, not limited by the height of the container.

2. The indication is novel, the reading is intuitive, eye-catching, and the direction of the observation indicator can be changed according to the user's needs.

3. It is suitable for the measurement of liquid level and interface in the container. Besides on-site indication, it can also be equipped with remote transmitter, alarm switch and complete detection functions.

4. Simple structure, convenient installation, convenient maintenance, corrosion resistance, no power supply, explosion-proof.

How to judge, cause and solve the problem that the indication of magnetic flap liquid level gauge is not correct in the measurement process.

1. Judgment method

(1) the container is always in operation, but the liquid level of the container is always stopped at a certain point.

(2) increase or decrease the load of the container and keep the liquid level unchanged.

(3) the local level gauge is inconsistent with the pressure difference level gauge on the indoor display screen.

2. reasons

(1) the water in the container rises or falls too fast, that is to say, the float rises or falls too fast, and the magnetic flap does not turn.

(2) the center of gravity of the magnetic flap is not at the center point. When the maglev rises, it turns over with the maglev. When the maglev rises again, the flap returns to the original position state, without indicating the state of water level.

(3) there are too many water impurities in the container, which are adsorbed on the surface of maglev. When the magnetic levitation decreases and rises, the flap cannot be driven to rotate.

(4) the actual water level in the container will rise due to different blockage of liquid-phase conduit of water. The maglev does not rise with it.

3. Solutions

(1) try to make the water level in the container rise or fall not too fast.

(2) magnetic flap of water level gauge, the center of gravity is not at the center point. If the manufacturing quality does not meet the standard, it shall be replaced.

(3) if the water quality is unqualified, wash it regularly.

4. Maintenance

(1) there shall be no solid impurities and magnetic impurities in the liquid level gauge barrel to avoid jamming the float and weakening the buoyancy.

(2) according to the medium condition, the main pipe can be cleaned regularly to remove the sediment impurities in the pipe.

(3) after cleaning the liquid level gauge or replacing the float, open the drain flange, and when installing the magnetic float, pay attention to the heavy end with the magnetic end upward, not inverted.

(4) for low-temperature and liquefied gas special products, the main body of liquid level gauge adopts vacuum jacket for heat preservation. During installation and use, pay attention not to damage the jacket to avoid affecting product quality.

Ten suggestions for the use of magnetic flap level gauge:

1. Before use, the small ball below the zero position shall be set to red with the correction magnetic steel, and the other balls shall be set to white;

2. Open the bottom flange and install the magnetic float (Note: the heavy end with the magnetic end is upward and cannot be inverted.) ;

3. During commissioning, open the valve of the upper approach pipe, then slowly open the valve of the lower part and the pressure calibrator to let the medium enter the main pipe stably (avoid the medium from impacting the float rapidly during operation, which will cause the float to fluctuate sharply and affect the display accuracy), observe whether the magnetic red and white ball rotates normally, then close the valve of the lower approach pipe, open the drain valve and make the liquid level in the main pipe drop, According to this method, it can be operated for three times, which is normal, and then it can be put into operation (except for corrosive and other special liquids)

4. The installation of magnetic flap liquid level gauge must be vertical, and the ball valve shall be installed between the magnetic flap liquid level gauge and the vessel lead pipe to facilitate maintenance and cleaning; the installation position of the magnetic flap liquid level gauge shall avoid or be far away from the inlet and outlet of the material medium, avoid the rapid change of the local area of the material fluid, and affect the accuracy of the liquid level measurement;

5. Clean the main pipe irregularly to remove impurities according to the medium conditions;

6. When equipped with remote supporting instruments, the following shall be done:

The sensing surface of remote transmission supporting instrument shall face and cling to the main pipe;

The remote supporting instrument shall be close to the main pipe of liquid level gauge and fixed with stainless steel hoop (iron is forbidden);

The zero position of remote transmission supporting instrument shall be on the same horizontal line with the zero position indication of liquid level gauge;

The connection between remote transmission supporting instrument and display instrument or industrial control computer should be laid separately through protective pipe or shielded two core cable;

After the wiring hole of junction box is laid, it is required to be well sealed to avoid the invasion of rain, moisture, etc., which makes the remote supporting instrument unable to work normally. The junction box shall be timely covered after the completion of maintenance or commissioning.

7. The medium shall not contain solid impurities or magnetic substances, so as to avoid jamming the float;

8. The installation position of the magnetic flap liquid level gauge shall be kept away from or away from the inlet and outlet of the material medium to avoid the rapid change of the local area of the material fluid and affect the accuracy of the liquid level measurement;

9. When debugging the magnetic flap liquid level meter, first open the valve of the upper approach pipe, then slowly open the valve of the lower part, so that the medium can enter the main pipe stably (avoid the rapid impact of the medium on the float during operation, which will cause the float to fluctuate sharply, and affect the display accuracy), observe whether the magnetic red and white ball is turning normally, then close the valve of the lower approach pipe, open the drain valve, and let the liquid level in the main pipe drop, According to this method, it can be operated for three times, which is normal and can be put into operation (except for corrosive and other special liquids);

10. For the liquid level meter over a certain length (common type > 3M, anti-corrosion type > 2m), it is necessary to increase the middle reinforcement flange or ear climbing as the fixed support to increase the strength and overcome its own weight;

The magnetic flap liquid level meter is characterized by simple structure, intuitive and clear observation, no blockage and leakage, convenient installation and simple maintenance. The upper and lower mounting flanges of the liquid level gauge are connected with the container to form a connector. The actual height of the liquid level in the container can be directly observed through the external magnetic flap or the display panel of the magnetic flap column. It is usually used for the liquid level detection of various towers, tanks, spherical vessels, boilers and other equipment.