Instructions for Using Magnetic Level Gauges

A magnetic level gauge (also known as a magnetic flap level gauge or magnetic float level gauge) is a liquid-level measurement instrument that operates on the principle of communicating vessels and magnetic coupling. It is widely used in storage tanks, reaction vessels, and other containers across industries such as shipping, chemical processing, and power generation. Its operation comprises four key steps: installation, commissioning, calibration, and routine maintenance; adherence to proper operating procedures directly affects measurement accuracy and equipment service life.

I. Installation Steps

Vertical installation
The level gauge must be installed strictly vertical to the ground (with a deviation of no more than 1°); otherwise, the float may become jammed or the readings may be inaccurate. For side-mounted gauges, the zero point must align with the lowest liquid level in the vessel; for top-mounted gauges, the insertion depth must cover the full measurement range, and the bottom of the gauge must be at least 50 mm above the vessel bottom.

Flange connection

Flange connections shall be made using sealing gaskets (for high-temperature media, metal-jacketed gaskets are recommended);
Tighten the bolts diagonally in stages to prevent misalignment and leakage.
A drain valve is installed at the bottom for easy cleaning and calibration in the future.

Avoid interference sources

No ferromagnetic objects (such as iron plates or magnets) shall be allowed to come near the level gauge body, and the use of iron wire for fixation is prohibited to avoid compromising the magnetic coupling effect.
If heat tracing is required, non-magnetic materials (such as red copper tubing) must be used.

Install the float
Open the bottom flange and install the magnetic float with the magnetized end facing upward; inversion is strictly prohibited.

II. Commissioning Operations

Valve Opening Sequence

First, slowly open the upper vent valve to release the gas;
Then slowly open the lower valve to allow the liquid to enter the level gauge chamber smoothly;
Never open the valve fully and rapidly to prevent liquid jet impact from damaging the float or causing the indicator column to malfunction.

Display observation status
As the liquid level rises, the indicator flags should change from white (or silver) to red, with the red–white boundary indicating the actual liquid level. If the flags fail to move or the display becomes erratic, the system must be inspected for faults.

Remote transmission function test (if equipped)
Connect the 4–20 mA signal output line, use a multimeter to verify that the current variation is synchronized with the liquid level, and calibrate the zero point (4 mA) and full-scale point (20 mA).

III. Calibration Before Use
Use a calibration magnet to slowly slide along the surface of the flip column, forcibly aligning the flipping direction.
The requirement is that “red is displayed below the zero position and white above the zero position” to ensure the initial state is correct.
IV. Precautions for Daily Use

Prevent float jamming

The medium must be free of ferromagnetic impurities or large particles; otherwise, they may adhere to the float and cause it to jam.
For dirty media, it is recommended to install a filter at the inlet and perform regular blowdown and flushing.

Regular maintenance

Monthly, gently tap the outer casing or briefly open the drain valve to prevent crystallization or deposition.
Clean the main conduit irregularly to remove internal impurities.

Avoid operation beyond limits

Operating pressure and temperature shall not exceed the ratings specified on the nameplate (e.g., PN 1.6 MPa, ≤200°C).
The liquid level should not be maintained at full scale or zero for extended periods to prevent the float from becoming jammed or experiencing dry friction.

Addressing the “magnetic interference” phenomenon
If vibration or a strong magnetic field causes the column display to become erratic, use a calibration magnet to gently slide along the surface to reset it, or drain the fluid and refill it.

Installation Location Selection
Avoid areas of fluid disturbance, such as material inlets and outlets and agitators, to prevent turbulence from compromising measurement accuracy.