Magnetic Level Gauge/Indicator

What is a magnetic type level gauge?

A magnetic Level Gauge is also called a magnetic level indicator. Magnetic Level Gauge is developed based on the principle of buoyancy and magnetic effect. The magnetic float in the measuring cylinder drives the two-color turning column on the external display of the measuring cylinder to flip with the increase (decrease) of the liquid level to be measured. As the position of the float changes, the indicator moves up and down the same amount. Supports top-mounted and side-mounted. It can be used for liquid level detection in high temperature, low temperature, high pressure, strong corrosion, highly toxic and dangerous environments.

Magnetic Level Gauge/Indicator

The parts and components of Magnetic Level Gauge are made of 304, 321, 316L, 1Cr18Ni9Ti, 00Cr17Ni14Mo2, 0Cr18Ni9, 304 or 0Cr18Ni9 lined with PTFE (polytetrafluoroethylene), PVC, PP, and other materials. And imported high-quality electronic components. The product has high reliability, good stability, long-lasting durability, and strong corrosion resistance.

Its characteristics are very significant:

  • Simple structure, Sturdy and reliable, durable, almost no maintenance workload, can be installed and used outdoors for a long time;
  • The measured medium is completely isolated from the display part of the level gauge, the level sensor, and the magnetic switch;
  • Wide working pressure range, withstand pressure from vacuum to 42MPa. The lowest density can reach 0.45g/cm3;
  • Wide operating temperature range, suitable for -190~+425℃;
  • Not affected by the physical and chemical state of the measured medium. Such as the medium’s conductivity, dielectric constant, foam, pressure, temperature, evaporation, boiling, bubbles, etc. It is widely used in various strong and weak corrosive, flammable and explosive. Toxicity, strong radioactivity, agitated, dirty liquid level, and interface measurement;
  • Optional single-pole single-throw (SPST), single-pole double-throw (SPDT) passive bistable magnetic switches. Realize high and low liquid levels, interface control, or alarm. The number of magnetic switches is not limited.
  • Optional reed pipe liquid level sensor, magnetostrictive liquid level sensor, capacitive two-wire liquid level sensor. Output 4~20mADC (or with HART protocol) signal. Realize remote centralized measurement and control.
  • The two-wire liquid level sensor can be equipped with LED digital display, which is convenient for night observation.

Installation form content



Installation spacing

Stainless steel



(Survey range)



Work pressure



Media density



Fallan Connection

Stainless steel

Farange 20-40 (DN20 PN1.0-4.0)

Farange 200-25 (DN200 PN1.6)


Farange 20-10 (DN20 PN1.0)

Farange 200-6 (DN200 PN0.6)

Main material

ICr18Ni9Ti, ABS, PP-R (working pressure of 0.6MPa)

Medium temperature


Environmental temperature


Schematic error


Medium viscosity

≤1st(10-4 /s)

Upper and lower limits
Switch output

1, control sensitivity: 10mm
2, output connector capacity: AC220V 2A
3, connection life: 5 × 104 times
4, explosion-proof characteristics: iaIICT4 essential safety type

Electric teletransmission and continuous display

1, accuracy:±1.5%
2, Output load: 750 Ω
3, output signal: 4~20mA output, 24V DC second-line system
4, explosion-proof characteristics: iaIICT4 essential safety type

In order to meet the needs of different occasions, environments, and functions, Magnetic Level Gauge can add the following options:

  • Optional single-pole single-throw (SPST), single-pole double-throw (SPDT) passive bistable magnetic switches to achieve high and low liquid level, interface control or alarm. The number of magnetic switches is not limited.
  • Optional two-wire magnetic liquid level sensor, output 4~20mADC signal, realize remote measurement and control,
  • Optional two-wire magnetostrictive or capacitive liquid level sensor, output 4 ~ 20mADC, to achieve high-precision, continuous measurement and control. Selection of the technological interface form of the level gauge.
  • The top and bottom structure of the level gauge are selected. Output 4~20mADC with HART protocol

Image source:

The Magnetic Level Gauge adopts the principle of the communicating device and is connected to the container through the gas-phase and liquid-phase connection flanges. According to the principle of buoyancy and magnetic coupling, the magnetic float in the measuring cylinder (that is, the communicating device) drives the two-color flipping column on the external display of the measuring cylinder to flip with the increase (decrease) of the liquid level to be measured.

When the liquid level rises, the magnetic float drives the turning column to rotate 180°, displaying red or green; when the liquid level drops, the magnetic float drives the turning column to rotate 180° in reverse, displaying white. The height of the red band (or green band) is the height of the measured liquid surface, which realizes the purpose of measuring and displaying the position of the measured liquid (interface) surface.

Each magnetic turning column is a two-color axial symmetric structure. The distance between the two magnetic turning columns is 10mm. White and red (or green) are used to indicate the gas phase and the liquid phase, and the red (or green) and white junctions It is the boundary between the liquid phase and the gas phase.

Magnetic Level Gauge can measure both the liquid level and the interface between two different density media.

Product standards: HG/T2742-1995, HG/T21584-95.
Flange executive standard: HG/T20592~20615—2009 (when the order is not specified)

The working principle of the magnetic level gauge is to communicate with the container, so the liquid level in the measuring chamber will be the same as the liquid level in the container. The measuring chamber is equipped with a float, and there is a magnet in the float.

The float with magnets will float on the medium, and the magnets in the float will rotate the flaps of the indicating rail. The float in the measuring tube is standard, there is no pressure, no magnetism, or mechanical guidance.

This structure makes the risk of the float lower than that of the standard pressurized float. When necessary, pressurized floats can be produced.

With the below-mentioned process conditions, it is possible to select a float that will float on the medium.

  • Medium
  • Density
  • Working pressure
  • Operating Temperature

Magnetic Level Indicators can be directly used to observe the level of the medium in various containers. It is suitable for liquid level indication in petroleum, chemical, and other industrial fields. The liquid level gauge has a simple structure, intuitive and clear observation, no blockage, no leakage, convenient installation, and simple maintenance.

Extended reading: RF Admittance Level Sensor

Magnetic Level Gauge can be widely used in petroleum, chemical, oil field, medicine, food, wine, and other industries.

Various liquid storage tanks, storage tanks, liquid storage tanks, reaction tanks, fermentation tanks, liquid ammonia storage tanks, ammonia separators, boiler drums, deaerators, drain boxes, return tanks, high and low-pressure heaters, condensers, Evaporator.

Measurement and display of the liquid level of the medium compatible with 304, 321, 316L, OCr18Ni9, 304 or 0Cr18Ni9+PTFE, 00Cr17Ni14Mo21Cr18Ni9Ti, PVC, PP, and other materials in other pressure vessels, and the interface of two different media.

There are a variety of installation forms for you to choose from, to meet the requirements of different occasions and environments.

Magnetic Level Gauge can be reliably used for liquid level detection in high temperature, low temperature, high pressure, strong corrosion, highly toxic, and dangerous environments.

Magnetic Float Level Switches & Sensors with Magnetic Reed Switches for Continuous Level Measurement.

Magnetic Float Level Sensor works with Reed Switch, is a continuous level sensor. SI-U04 Magnetic Float Level Sensor-Reed operates on a direct, simple principle. As the magnetic float rises and falls as liquid levels change. The magnetic field generated from the inside of the float drives the sealed reed switch installed in the stem. The stem is made of non-magnetic metal or strong engineering plastic.

Magnetic Float Level Sensor gets the liquid level signal, transfers it into digital current signal and switching signal. Generally speaking, there are two structures of magnetic floats. Besides, the Magnetic Float Level Sensor supports multiple mounting methods. Such as top-mounted, side-mounted. So SI-U04 Magnetic Float Level Sensor can be applied to a variety of tank level measurements.

Extended reading: Amazing Solutions for Continuous Liquid Level Measurement

Still have questions?

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More Featured Level Gauges/Indicators

SI-U01 Float Level Sensor
SI-U02 Multi-Point Liquid Level Float Switch
Rigid Probe Magnetostrictive Level Transmitter
Integral flange Magnetostrictive level sensor
Digital Display Magnetostrictive liquid level sensor

Based on the product selection, we can determine the price of the level transmitter. Sino-Instrument is a manufacturer of level transmitters, so we offer the best price.
For example: The reference price of a differential pressure level transmitter is around USD 400.

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About KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects. Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.