The magnetic flap level gauge is a liquid level measuring device based on the principle of buoyancy and magnetic coupling.
Working principle
1. Buoyancy effect
The core component of a magnetic flap level gauge is a float enclosed in a measuring tube. When the liquid level rises or falls, the float moves with it.
2. Magnetic coupling transmission
The float contains a permanent magnet, and the movement of the float drives the magnetic flip plate on the external display panel to flip, usually red or white to indicate the liquid and gas areas respectively, thus indicating the liquid level.
3. Signal output
• The measuring tube side can be equipped with reed tube or magnetostrictive sensor for detecting the position signal of the maglev.
• The electronic module converts the level change into a standard analog signal (e.g., 4 ~ 20mA) or a digital signal for transmission to the remote monitoring system.
Limitation
1. Applicable media
The magnetic flap level meter is mainly suitable for liquids with a density greater than the float density. If the density of the liquid is too low or close to the density of the float, the insufficient buoyancy causes the measurement to be inaccurate.
2. Temperature and pressure limitations
• High temperature will affect the magnetism of the magnet, will fail after a certain temperature, need to choose high temperature resistant materials.
• The high-pressure vessel must be designed to withstand pressure; otherwise, the pipe or float will be deformed.
3. Viscous and crystalline substances
The viscous liquid will increase the friction of the float and affect the movement flexibility. A medium that is easily crystallized or with suspended matter may trap the float.
Installation method
1. Install it vertically
Ensure that the measuring tube is vertical when installed. Deviation will block the float and cause measurement errors.
2. Media inlet and outlet
The inlet pipe mouth should not directly impact the float, so as to avoid strong impact on the float, affecting the life and measurement accuracy.
3. Clean and protect
Check and clean the measuring tube before installation to prevent welding slag or debris from affecting float movement. For corrosive media, anticorrosive materials should be selected.
4. Install in bypass mode
The magnetic flap level gauge is usually installed on the side of the storage tank or container in the form of a bypass tube to ensure that the liquid level is synchronized with the liquid level in the container.
Convert float height to a 4 to 20mA signal
1. Principles
• Magnetostriction or reed tube resistance chain technology can be used for position detection.
• When the float moves with the liquid level, its magnetic field action triggers the measuring element to generate a resistance or frequency signal, which is converted by the transmitter into a standard 4 to 20mA signal.
Extended application and improvement suggestions
1. Remote monitoring and intelligence
Combined with the wireless transmission module, the magnetic turnover level meter can achieve remote monitoring and control of data through the industrial Internet of Things.
2. Improved environmental adaptability
• For high temperature and pressure environments, use ceramic or high temperature stainless steel.
• For corrosive media, choose PTFE or other special coatings.
3. Compatible with various output signals
In addition to 4 ~ 20mA, the design supports intelligent output modes such as Modbus and HART protocol to improve the compatibility with the automation system.
Conclusion
The magnetic flap level meter is simple, intuitive and durable, and is suitable for a variety of liquid level measurement occasions. Despite the limitations of temperature and media, its application range and reliability can be further improved through reasonable selection and improvement.
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