Magnetic separators with pull-out grids

Metal contaminants can enter dry production mixtures during processing, transport, storage or as a result of wear on production equipment. These may include iron shavings, filings, wire fragments, scale, pieces of screws or extremely fine ferromagnetic dust.

A telescopic separator captures these particles before the material enters a mill, crusher, injection moulding machine, press, fine screen or packaging equipment. This helps prevent damage to production technology while improving the purity of the final product.

What is a telescopic magnetic separator?

An MSV telescopic magnetic separator is a housing-type grid separator designed for industrial piping systems carrying dry material.

The device consists of an enclosed body containing removable magnetic grids. These grids are made from stainless-steel tubes with powerful neodymium magnetic cores inside.

Main components of the separator

• stainless-steel body installed in the pipeline,
• one or more removable magnetic grids,
• magnetic rods with neodymium cores,
• protective stainless-steel tubes,
• flanges or other pipeline connections,
• locking elements and handling handles,
• optional separate cleaning fixture.

How does a telescopic magnetic separator work?

The separator is installed in a vertical pipeline. Material enters from above and falls under its own weight through the magnetic grids.

1. Dry material enters the upper section of the separator.
2. The grids create a magnetic labyrinth and divide the material flow.
3. Ferromagnetic contaminants enter the strong magnetic field.
4. The particles are attracted to the surface of the stainless-steel tubes.
5. The cleaned material continues through the lower outlet.
6. Captured contaminants remain on the grids until cleaning.

In the Classic range, the grids are usually arranged in two levels above one another. The material therefore cannot simply fall through one open path but must change direction several times and pass close to the magnetic tubes.

Why is the magnetic labyrinth important?

A powerful magnet can only act effectively on a particle that comes sufficiently close to its surface. If material were able to fall through the separator along a straight open path, some metal contaminants could bypass the magnetic field.

A correctly designed labyrinth:

• spreads the material across the separator area,
• guides it around several magnetic tubes,
• reduces the formation of unrestricted flow paths,
• increases the exposure time to the magnetic field,
• improves the likelihood of capturing fine particles.

Which metal contaminants can an MSV separator capture?

A telescopic separator is designed for ferromagnetic materials that can be strongly attracted by a permanent magnet.

Typical captured contaminants

• iron and steel shavings,
• particles of ordinary magnetic steel,
• scale,
• wire fragments,
• fine ferromagnetic dust,
• particles caused by machine wear,
• small fragments of screws and fasteners.

What will a standard MSV separator not capture?

• aluminium,
• copper,
• brass and bronze,
• plastic,
• glass,
• wood,
• ordinary non-magnetic contaminants,
• some grades of stainless steel,
• products containing only a small enclosed steel component.

The equipment is not a substitute for a mechanical screen or filter. If the material may contain large non-magnetic pieces, suitable protection must be installed upstream of the separator.

Which materials can pass through the separator?

MSV separators are designed for dry, homogeneous, non-sticky and free-flowing materials. The mixture must be able to fall freely through the magnetic grids and must not form bridges or lumps between them.

Examples of suitable materials

• plastic granulate and regranulate without glass additives,
• rubber regranulate and suitable rubber crumb,
• grain and finely processed agricultural products,
• rice, lentils, chickpeas and selected seeds,
• sugar, cocoa, coffee and spices,
• animal feed mixtures,
• dried food powders,
• fine dry sand with more frequent wear inspection,
• selected construction mixtures,
• finely shredded PET and other free-flowing recycled materials.

What properties must the material have?

• it must be dry,
• it must not be greasy or sticky,
• it must have good flowability,
• it must not contain large hard pieces,
• it must not form solid clumps,
• its particle size must be suitable for the specific separator,
• it must not clog or mechanically damage the grids.

Why is an MSV separator unsuitable for wet and sticky materials?

Wet, greasy or sticky mixtures can adhere to the magnetic tubes and gradually close the flow gaps.

Problems may also occur with extremely fine powders that tend to bridge, such as some finely milled flours or starches.

Possible consequences of unsuitable material

• blocked magnetic grids,
• uneven loading of the separator,
• significantly reduced capacity,
• captured particles becoming coated with normal material,
• reduced magnetic performance,
• difficult and hazardous cleaning.

Flow-type magnetic separators of a different design are intended for wet, liquid or semi-liquid materials.

Is an MSV separator suitable for abrasive material?

The magnetic tubes have very thin stainless-steel walls in order to achieve high magnetic performance. Abrasive material can gradually wear them down.

Higher-risk materials include:

• sand,
• crushed glass,
• ceramic particles,
• granulates containing glass fibres,
• hard mineral mixtures,
• material falling from a great height.

If use with a particular abrasive material is permitted, the condition of the tubes must be checked more frequently. A worn-through or dented tube creates a risk of damage to the magnetic core and contamination of the product.

What is the maximum permitted material drop height?

Material must not fall onto the magnetic grids from an unlimited height. Hard or heavy particles can damage the thin protective tubes on impact.

For this type of separator, a general maximum drop height of approximately 1 metre is often stated. However, the actual safe height depends on the density, size, hardness and velocity of the material.

Equipment protection or product purity?

Separation for equipment protection

The separator is installed upstream of equipment that could be damaged by metal objects.

• mills and crushers,
• cutting blades,
• granulation and regranulation lines,
• injection moulding machines and extruders,
• pressing equipment,
• fine screens,
• ceramic and glass presses.

In this case, the main objective is to capture particles that could cause mechanical failure, blockage or production downtime.

Separation for improved product purity

If the objective is product purity, the separator is installed at the end of the process or at several consecutive points along the production line.

After the final separation stage, the cleaned material should be enclosed in packaging or a container as quickly as possible to prevent recontamination.

Why is the separator intended for non-continuous operation?

Manually cleaned MSV separators must be removed from the material flow during maintenance. The material feed must therefore be stopped before the magnetic grids are withdrawn.

If production cannot be interrupted regularly, a more suitable solution may be:

• an automatically cleaned telescopic separator,
• a rotary magnetic separator,
• two separators used alternately,
• another continuous magnetic separation solution.

Why is an MSV separator installed in a vertical pipeline?

The equipment uses gravity to move the material through the magnetic labyrinth. In a vertical position, the mixture naturally falls through the separator.

In a horizontal pipeline, material could accumulate inside the separator body, load the grids unevenly and gradually cause blockage.

Telescopic magnetic separator product ranges

MSV ECO

The ECO range offers a more economical solution for applications where maximum cleaning convenience is not a priority.

Main features

• simpler construction,
• lower purchase price,
• powerful neodymium magnetic rods,
• manual removal of contaminants from the tube surfaces,
• versions for round and rectangular pipelines,
• suitable for less frequent cleaning.

The ECO version is suitable where the amount of captured metal is low and the grid does not need to be cleaned several times during a shift.

MSV Classic

The Classic range is the most common universal version with removable magnetic grids. Material normally passes through two levels of magnetic rods that create an effective labyrinth.

Main features

• high level of separation,
• versions for round and rectangular pipelines,
• removable magnetic grids,
• removable magnetic cores,
• easier manual cleaning,
• wide range of sizes,
• powerful neodymium magnets.

The Classic range is suitable for most standard industrial applications involving dry and free-flowing materials.

MSV UP

The UP range is designed for more demanding applications and frequent cleaning. Its construction allows individual components to be withdrawn separately and reduces direct handling of the powerful magnetic cores.

Main features

• very high magnetic performance,
• compact modern construction,
• convenient cleaning system,
• improved operator safety,
• no separate external cleaning fixture required,
• versions for round and rectangular pipelines,
• custom dimensions available.

How do you choose the right MSV size?

The separator dimensions must match the pipeline, amount of material and required capacity.

Inlet and outlet diameter

The DN designation must match the pipeline or transition components in the production system. A separator that is too small can significantly restrict material flow.

Number of magnetic rods

More rods create a larger active surface and a denser labyrinth. At the same time, however, they reduce the open area available for the material to pass through.

Material properties

Two different materials may achieve very different capacities in the same separator size. Flowability, particle size, particle shape, bulk density and tendency to bridge are all important.

Required level of purity

Lower magnetic performance may be sufficient for protecting equipment. Higher-performance magnetic cores are used for fine particles and higher product purity.

What does magnetic flux density in Gs mean?

Magnetic flux density describes the intensity of the magnetic field at a specific measurement point on the surface of the magnetic tube.

A higher value may help capture finer ferromagnetic particles, but on its own it does not describe the overall efficiency of the separator.

What does pull-off force in N mean?

Pull-off force indicates the force required to separate a defined steel test piece from the surface of the magnetic tube.

A higher pull-off force helps keep captured particles attached to the tube as material passes through.

Which is more important, Gs or N?

Both values must be assessed together with the separator design.

• magnetic flux density,
• pull-off force,
• number of magnetic tubes,
• tube diameter,
• spacing and arrangement of the grids,
• material feed rate,
• cleaning frequency.

How is a telescopic separator installed?

1. Check the pipeline diameter and design.
2. Make sure there is enough space to fully withdraw the grids.
3. Install the separator only in a vertical position.
4. Provide a secure and leak-tight pipeline connection.
5. Make sure the weight of the equipment does not place unsuitable loads on weak piping.
6. Provide a safe working area for cleaning.
7. Remove loose ferromagnetic objects from the surrounding area.
8. Check all clamps and locking elements before operation.
9. Carry out a flow test using a smaller amount of material.

How much space is required for cleaning?

The grids must be able to slide completely out of the separator body. Sufficient handling space must therefore remain beside the separator to accommodate the full component length and cleaning fixture.

How often should an MSV separator be cleaned?

There is no universal interval. The separator must be cleaned before a thick layer of metal builds up on the magnetic tubes or begins to reduce the flow gaps.

Cleaning frequency depends on:

• amount of ferromagnetic contamination,
• volume of processed material,
• size of metal particles,
• number of rods,
• required product purity,
• risk of damage to downstream equipment.

When first commissioning the separator, inspect the grids more frequently. A fixed cleaning interval can then be established according to the actual amount of captured metal.

Why does an overloaded grid lose efficiency?

New metal particles are captured on top of the existing build-up and are therefore farther away from the magnetic core.

A heavy build-up can:

• reduce magnetic holding force,
• reduce flow gaps,
• trap ordinary material,
• cause blockages,
• allow some of the captured metal to be released again,
• damage the stainless-steel tubes.

How do you clean an MSV separator safely?

Cleaning may only be carried out after the material flow has been completely stopped and the production equipment has been secured.

1. Stop material dosing and flow.
2. Secure the equipment against accidental start-up.
3. Open or unlock the separator according to the instructions.
4. Carefully withdraw the magnetic grids.
5. Secure the grid in a cleaning fixture if one is used.
6. Unlock the magnetic cores.
7. Slowly pull the cores out of the protective tubes.
8. Place them in a safe non-magnetic holder.
9. Allow the captured contaminants to fall into a container.
10. Remove any remaining particles with a dry brush or suitable tool.
11. Inspect the condition of the protective tubes.
12. Return the cores to their operating position.
13. Slide the grids back in and secure them safely.

Can the separator be cleaned with water?

The magnetic cores must not be immersed in water or cleaned using high-pressure water. Water may enter the construction and damage the magnets or internal components.

Suitable methods for removing residues include:

• a dry cloth,
• a dry brush,
• a non-magnetic scraper,
• thoroughly dried compressed air, if permitted by the operating procedure.

The cleaning method used for components that come into contact with the product must also comply with the hygiene requirements of the specific facility.

Why use a cleaning fixture?

A separate fixture holds the grid and magnetic cores in a safe position during maintenance.

Main advantages

• improved operator safety,
• lower risk of magnetic cores snapping towards a steel structure,
• more convenient removal of the magnets,
• easier release of captured metal,
• protection of the protective tubes,
• faster routine maintenance.

How should the condition of the separator be inspected?

• inspect the surfaces of the protective tubes,
• look for dents, scratches and abrasion,
• inspect welds and joints,
• check the condition of flanges and seals,
• inspect clamps and locking mechanisms,
• make sure the grids move freely,
• regularly measure magnetic flux density,
• regularly measure pull-off force,
• keep records of cleaning and inspections.

When should the separator be taken out of service?

Do not use the equipment if a tube is punctured, heavily dented or worn through, if the grid cannot be secured safely or if the magnetic core is damaged.

Is an MSV separator suitable for the food industry?

Selected models made from AISI 304 stainless steel can be used in food-processing applications provided that the complete design and installation meet the requirements of the specific facility.

In particular, verify:

• material of all parts in contact with the product,
• surface finish,
• weld design,
• seals,
• possibility of hygienic cleaning,
• risk of dead spaces,
• internal HACCP and audit requirements,
• chemical resistance to cleaning agents.

Can the separator be used outdoors or in an ATEX environment?

Standard stock MSV separators are designed for indoor industrial use only.

They are not automatically suitable for:

• outdoor environments,
• permanently wet conditions,
• potentially explosive atmospheres,
• aggressive chemical environments,
• areas with uncontrolled high temperatures.

An explicitly designed and approved version must be used for ATEX or other special operating conditions.

Safety when working with MSV separators

Recommended telescopic magnetic separators

The selected products represent three different separator sizes from the Standard range – a compact DN 50 model, a universal DN 150 model and a larger DN 200 separator with a greater flow area.

Frequently asked questions about telescopic magnetic separators

Summary

An MSV telescopic magnetic separator removes ferromagnetic contaminants from dry, homogeneous and free-flowing mixtures. It is installed in a vertical pipeline and uses one or more removable magnetic grids.

The equipment can protect production technology or improve the purity of the final product. It is not suitable for liquid, wet, sticky, coarse or highly abrasive materials without prior technical assessment.

When selecting a separator, consider the pipeline DN, particle size, flowability, required capacity, amount of metal contamination, number of rods, magnetic performance and available cleaning space.

A manually cleaned separator requires the material flow to be stopped. The magnetic cores are extremely powerful and must be cleaned according to a safe procedure, ideally using a suitable cleaning fixture.