Among many liquid level measuring instrument, magnetic flap level meter is a common liquid level measuring instrument, widely used in petroleum, chemical, sewage treatment and other industries, because of its simple structure, easy installation, reliable measurement, intuitive display and other characteristics, favored by the majority of users. Magnetic flap level meter can be divided into various types according to the different forms of installation, the top installation is one of the more common. Because it is generally installed on the top of the container, often referred to as top-mounted magnetic flap level meter, is ideal for underground storage tanks, the side of the ground container is not convenient to open the hole, as well as the measured liquid medium viscosity is not suitable for side installation of the level measurement on the tank.

The main structure of the top-mounted magnetic flap level meter is generally divided into two parts: upper and lower. The upper part is the main measuring tube of the level meter, and there is a display panel with magnetic flip-flop bundled outside the tube. The upper part is usually fixed on the top of the vessel by connecting flange, the connecting flange can be DN80, DN100 and DN150, the flange specification should not be less than DN80, the lower part is the guard barrel part, for the lower float floating up and down the channel, can prevent the float from liquid impact to swing around. The float in the guide tube is connected to the magnetic float in the upper measuring tube through the connecting rod. When the liquid level changes up and down, the float drives the magnet to move up and down in the guide tube, and the magnetic coupling of the upper float drives the flip flop in the display panel to turn over and indicate the liquid level.

Only when the liquid level at the bottom of the tank rises to a certain height, so that the buoyancy force on the float immersed in the liquid is greater than the total weight of the float assembly, the float assembly can float upward and can rise with the liquid level in the tank. Until the buoyancy force on the float is greater than the total weight of the float assembly, the float assembly cannot float, even though the liquid level is changing, until the liquid level rises so that the buoyancy force on the float is equal to the total weight of the float assembly, but at this time the change in liquid level at this height cannot be indicated by the flip-flop. This area where the level change cannot be indicated by the flip-flop is commonly referred to as the measurement blind zone. Generally speaking, the measurement blind zone is related to the length of the lower float, the longer the lower float, the larger the measurement blind zone.

It can be seen that, in the liquid level measurement, the top magnetic flap level gauge has a measurement blind zone, that is, even if there is no liquid in the tank, the instrument indicator will always have a section of the flap indication, resulting in the phenomenon of false liquid level.

For the measurement blind zone, the range of the measurement blind zone can be reduced or the blind zone display can be removed by several methods.

(1) Reduce the measurement blind area by making a fine float. In the production of top-mounted magnetic flip-flop level meter, by accurately understanding the density value of the measured liquid medium from the customer, when processing the magnetic float to ensure that the density of the processed magnetic float matches the density of the measured medium, so that the processed float is as short as possible, thereby reducing the measurement blind spot.

(2) Reduce the measurement blind area by increasing the specification of the connection flange. By increasing the specification of the connecting flange, the diameter of the top support pipe of the tank can be increased, so that the diameter of the float tube can be increased when making the lower float, so that the length of the float can be processed shorter to reduce the measurement blind area.

(3) Reduce the display blind area by a certain measuring range. If the customer is measured at the bottom of the tank, there is always a certain height of the liquid level gauge under normal circumstances, or do not need to monitor the level of the bottom of the tank, in the production of top-mounted magnetic flap level meter, you can follow a slightly shorter range to produce the level meter, that is, the instrument range processing, according to the actual range of the tank minus the length of the measurement blind area to produce the range, while the length of the lower shroud is still in accordance with the The length of the lower guard is still processed according to the actual measuring range of the tank, and the lower part is left with space for the lower float.

A magnetic flap level meter instrument, in addition to reliable quality, but also needs to be installed and used correctly. Only under the correct installation and use of the magnetic flap level meter, do diligent inspection and maintenance, can we ensure the reliable work of the level meter, stable operation and prolong its service life.

The above is about the top-mounted magnetic flap level meter measurement blind spot and what are the response methods? The introduction of this point of knowledge, if there are other places that do not understand or have a better proposal can be left in the comments section to discuss Oh!