As the liquid level rises in the tank, the float is lifted up due to buoyancy. The float moves inside a SS float chamber. External to this float chamber is a glass tube indicating PVC magnetic ball assembly which carries the magnetic follower. Due to magnetic attraction, the magnet on the float and the magnetic follower are coupled and move in union. So as the float moves along with the liquid, the follower capsule also moves inside the glass tube and PVC magnetic ball changes its colour, and the position of the follower capsule/magnetic ball can be read against the scale.

Introduction of slide-mounted magnetic Level indicator (with transmitter)

The slide-mounted magnetic level indicator with transmitter is an effective and trustworthy device that is applied to continuous level measurement and visual display of the liquid level within tanks and vessels. It is usually made of a float with a magnet, which rises and falls with the liquid level in a vertical or a side-mounted chamber (slide mount). The displacement of the float results in the rotation of a column of magnetic flaps or indicators in the outside scale, which changes color and gives a clear visual indication of level, but not electrically.

When combined with a transmitter, the device also gives the position of the float as an electronic signal (e.g., 4-20 mA) to allow remote monitoring and control. It suits high- or low-pressure applications, corrosive conditions, and where a clear and maintenance-free level measurement is critical. This blend of mechanical signal and electronic transmission provides local and remote-level indication of industrial processes.

Working principle of slide-mounted magnetic Level indicator

The slide-mounted magnetic level indicator works on the principle of magnetic coupling of a float and an outside visual indicator.

This is the way it works:

The indicator is a chamber attached to the side of a tank or vessel, with process nozzles attached at two points (top and bottom) so that liquid in the chamber rises and falls in line with the liquid level in the tank.

In the chamber, a float containing a permanent magnet that is fitted inside the float moves vertically as the liquid level changes.

A magnetic indicator rail (including bi-colored flaps or rollers) is mounted on the length of the chamber outside the chamber.

The float has a magnet inside that magnetically couples with the flaps or rollers as it moves, making them turn and change color (usually red liquid level and white vapor space).

This gives a visual, at a distance, indication of the level without any direct contact with the fluid.

With a level transmitter, the position of the float is also detected electronically and converted into a continuous signal (e.g., 4–20 mA) to allow remote level indication and integration with control systems.

This principle guarantees a leak-free, maintenance-free, accurate, and reliable measurement of liquid level.

Application of Slide mounted magnetic Level indicator

The slide-mounted magnetic level indicator is a very popular indicator used in most industries to measure liquid levels safely and reliably in even the most hostile conditions. It is mainly used in:

Chemical and Petrochemical Plants

To monitor corrosive, toxic, or flammable liquids where a sealed system is highly required due to safety reasons.

Oil and Gas Industry

Applied in storage tanks, separators, and scrubbers to gauge the level of oil, water, or any other process fluid.

Power Plants

To measure boiler feed water, condensate, and other important critical fluid levels at high pressure and high temperatures.

Pharmaceutical and Food Processing

Applicable in hygienic and sterile applications where there is a need for non-invasive and contamination-free level indication.

Wastewater and Water Treatment

Suitable in clean water, sludge, and chemical dosing tanks, providing both visual and remote level indication.

Pulp and Paper Industries and Fertilizer

Applied in storage tanks and process tanks that contain aggressive chemicals or high-temperature liquids.

This kind of level indicator is especially desirable when continuous level monitoring, low maintenance, and high visibility are needed even in hazardous or high-pressure applications.

Float selection Slide mounted magnetic Level indicator

A Slide Mounted Magnetic Level Indicator is centred around the float, and the choice of this float is important to ensure reliable and accurate level measurement. The choice of float is dependent on the application requirements, fluid properties and the process conditions. The most important factors and choices are listed below:

Important notes about Float selection:

SG: Fluid Specific Gravity:

The float should be less dense than the fluid so that it floats.

All floats are set to a certain range of SG (e.g., 0.6 or 0.8, and so on).

Pressure and temperature of operation:

The wall thickness and the float material should be able to resist the highest system pressure and temperature.

Fluid Compatibility:

The float material should be non-corrosive, non-scaling, or non-contaminating to the fluid.

Orientational and Mounting Style of Tanks:

In the case of slide-mounted (side-mounted) chambers, the float is made to slide horizontally or at an angle.

Popular float materials are

Stainless Steel (SS 316/SS 316L):

Applicable to the majority of industrial fluids; withstands high pressure and temperature.

Titanium:

Perfectly suited for highly corrosive or seawater environments.

Teflon (PTFE) Coated or All-PTFE:

In the case of aggressive chemical media (acids, alkalis).

Hastelloy/Monel/alloy 20:

In higher-end applications where high corrosion resistance is needed.

Customizations may consist of:

Compact or turbulent flow: different sizes and shapes (cylindrical, spherical).

Indicator system-based magnet type and orientation (axial or radial).

Longer-range multi-magnet or guided float designs or built-in transmitter systems.

Conclusion:

Proper float selection guarantees proper level monitoring, high operating life, and system security. To get a precise design of the float, it is usually advised to consult with the manufacturer by giving complete details of the fluid and process (SG, temperature, pressure, chemical composition).

Advantages of Slide mounted magnetic Level indicator

Merits of Slide-Mounted Magnetic Level Indicator

The slide-mounted magnetic level indicator has a number of advantages, and this is why it is used in the measurement of liquid in industries, particularly in harsh or critical conditions. The key benefits are as follows:

Visual Indication, Clear and Continuous

Gives a color-changing and easy-to-read visual display of liquid level, with no power needed to indicate locally.

No Indicator Exposure

The internal float is magnetically linked to the external indicator, and there is no possibility of fluid leakage and contamination.

Appropriate in Rough and Dangerous Conditions

Applicable with toxic, corrosive, or high-pressure fluids; suitable for industries such as chemicals, oil & gas, and power generation.

Maintenance-Free Operation

No rotating parts in direct contact with the process fluid and no sight glass to clean or replace, which leads to long-term, low-maintenance operation.

Two-Output Ability

Enables local visual signal as well as remote electronic output (when fitted with a transmitter) in order to be incorporated into SCADA or control systems.

Tolerance of High Pressure and Temperature

Robust design deals with severe conditions without affecting the accuracy or safety.

Safe against Flammable or Toxic Fluids

Safe operation even with hazardous liquids due to the presence of a fully sealed chamber and less exposure to the operator.

Flexible Mounting The mounting options of the equipment are versatile.

Slide-mounted (side-mounted) design can be used when top mounting is not possible on tanks.

Customizable Design

Floats, chambers, and indicators can be customized to suit specific application needs, including specific gravity, tank size, and material of construction.

Maintenance of Slide mounted magnetic Level indicator

The slide-mounted magnetic level indicator has long-term, low-maintenance application. Nevertheless, it needs periodic checkups and preventive measures to make it accurate, reliable, and safe. The major maintenance practices are as follows:

Routine Visual Inspection

Make sure that the indicator flaps rotate and change color.

Make sure that there are no leakages of fluid around the process connections or the chamber welds.

Check the float travel by noting whether the indicator shows real level changes.

External Indicator Cleaning

Wipe the indicator rail or housing using a soft, wet cloth to clean up dust or residue of the process.

Do not use strong chemicals that can destroy indicator markings or transparency.

Chamber and Float Check (The Shutdown)

Periodically (depending on the conditions of the application), the unit should be isolated and the chamber drained.

Clean and check the float to see whether it has accumulated sludge, scaling, or chemicals.

Check to ensure that float magnets are strong and intact, as they may influence accuracy.

Calibration Transmitter and Switch (where fitted)

On indicators that have transmitters or magnetic switches, verify calibration and output signals.

Check the wiring and signal integrity and ensure a 4-20 mA output range.

Review of Fluid Compatibility

In the event that the process fluid has been modified, check float material compatibility to ensure that it does not corrode or damage.

Change the float or chamber when there is evidence of chemical attack.

Mounting and Supports Check

Make sure that all flanges, bolts, and brackets are tight and secure.

Make sure that the indicator body has no mechanical stress or misalignment as a result of pipeline stress.

Schedule-Based Maintenance

In the case of critical systems, use a maintenance cycle (typically 6–12 months) depending upon the type of fluid, temperature, and pressure.

Types of Slide mounted magnetic Level indicator

Slide-mounted magnetic level indicators are available in many different types depending on the industrial needs of the specific applications according to the fluid characteristics, process conditions, and functional requirements. The typical ones are listed below:

Basic Slide-Mounted Magnetic Level Indicator (No Transmitter)

Only uses magnetic flaps or rollers to give local visual indication.

Suited to those applications where a basic, trouble-free level indication is needed and where remote communication is not necessary.

Slide-Mounted Magnetic Level Indicator-Transmitter

Fitted with a non-contact level transmitter (typically reed chain, Hall effect, or magnetostrictive).

Provides an analog output (e.g., 4-20 mA) to remote monitoring or control systems.

Slide-Mounted Magnetic Level Indicator Switches

Equipped with magnetic level switches to be used in high/low-level alarms or pump/control interlocks.

Switches may be variable and are externally mounted along the chamber.

High-Temperature and High-Pressure Type

Special design: reinforced chambers and superior float material (e.g., SS316, Hastelloy, or titanium).

Applicable in boilers, steam systems, and high-pressure tanks.

Corrosion-Resistant Type

They are made of PTFE-lined chambers, PP, or PVC, with PTFE-coated floats.

Applied to aggressive or corrosive chemicals in the chemical processing industries.

Dual Indication Type

Contains visual indicator + glass tube backup or secondary scale.

Provides redundancy in life-critical applications.

Miniature Type

Skid systems, OEM equipment, or small tanks.

Has a thinner chamber and float with a smaller mounting.

Conclusion:

The type of slide-mounted magnetic level indicator is a function of

Observation requirements (just sight or distant signal)

Characteristics of fluids (corrosive, viscous, and volatile)

Conditions of process (pressure, temperature)

Integration of safety and control (alarms, automation)

Recommend disposal of Slide mounted magnetic  Level indicator

The procedure to dispose of a slide-mounted magnetic level indicator should always be done in an environmentally and safety-compliant manner, and particularly so in the case of a slide-mounted magnetic level indicator that has been utilized with hazardous or corrosive fluids. This is a disposal guide step-by-step that is recommended:

Decontamination

Before removal, isolate and depressurize the system.

Empty and flush the chamber completely by draining all the fluid.

In case the device was utilized with dangerous or poisonous liquids, refer to the plant chemical handling procedures on neutralisation or safe handling.

Disassemble Components

Take apart the indicator into its major parts:

Float

Chamber/body

Magnetic indicator rail

Transmitter (where fitted)

Wiring and switches (when any)

Materials to Identify and Sort

Metal components (such as SS316, Hastelloy, or titanium) can be delivered to metal recycling centers.

Plastic or PTFE components ought to be dealt with as per plastic recycling or dangerous waste.

Electronic parts (transmitters, switches) are to be considered e-waste, and e-waste recyclers need to be used.

Magnets: Handle with Care

Strong magnets contained in the float or indicator can be hazardous and must be either well encapsulated or demagnetised prior to disposal or recycling.

Magnets should not be burned or compacted, as they can emit poisonous gases.

Documentation and Compliance

Keep disposal records in line with the company policy or local environmental law.

Have the device disposed of by authorised waste handlers or recyclers in case it has been exposed to hazardous media.

Environmental Consideration

Do not dispose of components in the general waste.

Whenever possible, reuse or recycle in order to have the least impact on the environment.