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Flap-11S Economical Type Magnetic Level Indicator

Cost-effective, particularly suitable for measuring slightly corrosive liquids, it is typically applied in fields as follow:

 Hydrogenated tail gas condensate receiver tank and liquid alkali evaporator of hydrogen peroxide devices in chlor-lkali Industry.

● Water tank at electrolysis plant.

 Level monitoring of a variety of storage tanks of industrial equipment.

  • Flap-11S Economical Type Magnetic Level Indicator, its most prominent features are economic and practical. This indicator uses 304 stainless steel, which is particularly suitable for measuring slightly corrosive liquids. The floating tube’s diameter is 51mm/57mm, and is made of high quality 304 seamless stainless steel tube, can effectively avoid the common defects, such as leakage, low pressure, unsightly appearance, and short life, etc. Also, Flap-11S has introduced innovative production and test processes to improve its reliability and quality.

  • Flap-11 Magnetic Level Indicator series products are designed based on communicating tube and the principles of magnetic coupling function to achieve real- time level measurements. When the measured liquid’s level in the vessel changes, the magnetic float in communicating tube will go up and down, and the permanent magnet steel inside the magnetic float makes the magnetic flaps of the indicator outside the communicating tube turn by 180° which is driven by the magnetic coupling function. Usually the front and back surface of flaps are coated with two different colors respectively (normally red and white) to indicate the actual liquid level inside the vessel. When the level of vessel rises, the flaps turn from white to red, and when the level of vessel drops, the flaps turn from red to white, at the red and white junction, the actual level of vessel is indicated. According to different chemical properties of the measured medium, appropriate materials for the communicating tube should be applied. In order to achieve to the best accuracy of measurement, the magnetic float’s weight, volume and structure have to be satisfied with the density of measured liquid. 

  • (1) Indicator panel and magnetic flaps uses widened design make visual distance and viewing angle increase greatly, the ruler and its figures are bolder and clearer.

    (2) Level of Ingress Protection of IP65 and IP66/67 are available, exceeding national standard requirement of IP54;

    (3) Accessory magnetic switches and remote transmitters have got double certifications of Explosion Proof and Intrinsically Safety.

    (4) Made of 304 seamless stainless steel tubes, which is cost-effective.
    (5) Used to monitor the level of a variety of storage tank of industrial equipment.

  • Fluid





    Measurement parameters

    Measuring range

    Single section: 200-5600mm 
    Multi-section: up to 20m or more


    ±5mm or ±10mm

    Material specifications


    304 , Ф51/Ф57, The thickness depending on the process condition


    304, 316L

    Indicator panel

    Optional aluminum flap or PA66 nylon flap, and optional cover plate of glass (standard) or acrylic.

    Operating conditions

    Process pressure


    Process temperature


    Ambient temperature


    Signal output


    220VAC 3A, SPDT



    Process connection

    Connection type

    Flange, customization



    End fittings

    Upper vent

    Flat welding cap, also can be configured flange, cocks, 1 / 2” NPT ball

    Lower drain

    1 / 2” NPT ball, also can be configured flange and cocks

    Additional devices

    steam jacket


    electric heating


    cryogenic insulation / heat insulation

    Synthetic rubber, asbestos, polyolefin

    Vacuum jacket

    Anti-frost, can be used in the occasion that temperature less than -5

    Safety certification

    Protection rating



    Ex d IIC T6,Ex ia IIC T6 (magnetic switch and transmitter)

  • ● Applied in hydrogenated tail gas condensate receiver tank and liquid alkali evaporator of hydrogen peroxide devices in chlor-alkali Industry.

    ● Used to measure the level of water tank at electrolysis plant. 

    ● Used to monitor the level of a variety of storage tank of industrial equipment.

  • Flap-11Px Lined Type Magnetic Level Indicator

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