Temperature Effect on Magnetic Separators
By Paul Fears | 14 July 2022
If a Neodymium Rare Earth Tube Magnet is put into a red-hot fire, then it would not be surprising if the magnetic properties are destroyed. However, what if the same Tube Magnet is just exposed to steam being flushed through a pipeline system to clean the pipes?
Tube Magnets manufactured with high quality Neodymium Magnets are able to operate well in temperatures up to 100 degrees C. There is a gradual drop in magnetic strength when the temperature rises above 80 degrees C, but this loss in magnetic strength recovers when the temperature falls back to normal levels.
However, as soon as the Neodymium Rare Earth Tube Magnets are exposed to temperatures exceeding 100 degrees C, the magnetic strength becomes compromised. On returning to normal operating temperatures below 80 degrees C, there is an irreversible loss in magnetic strength and permanent damage.
In a pipeline which is cleaned using steam, the temperature will be above 100 degrees C for a period of time. This will certainly damage any standard Neodymium Rare Earth Tube Magnets or Magnetic Separators (e.g. the Liquid Pipeline Magnets) installed in the pipeline. However, most users are totally unaware of the potential loss in magnetic separation performance and that the ability of the Magnetic Separator to remove small pieces of metal contamination has been permanently compromised.
Magnetic Separators in High Temperature Environments
There are types of Neodymium Rare Earth Magnets that are designed to operate in high temperature environments. These tend to be lower in magnetic strength at room temperature, but the magnetic field does not degrade as quickly as standard Neodymium Magnets at higher temperatures. Also, on returning to normal temperatures, there is only a small irreversible loss in magnetic field, which is only experienced when first exposed to high temperatures.
This type of high temperature Neodymium Rare Earth Magnet should be used in pipelines which are being cleaned for prolonged periods with steam.
For applications where there are extreme high temperatures (exceeding 150 degrees C), then the best option is to use Samarium Cobalt Rare Earth Magnets (SmCo). These retain their magnetic properties in temperatures up to 300 degrees C. However, such applications are rare.
It is recommended that the magnetic properties and strength of any Magnetic Separator installed in a pipeline cleaned with steam or in an environment where there is constant exposure to high temperatures is checked on a regular basis (e.g. during an annual Magnetic Separation Audit). The best way to do this is with a Magnetic Pull Test Kit.
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For further information on Magnetic Separators or to discuss a specific project, including arranging a site visit, please contact our technical sales team on:
Email: Gordon Kerr at GKerr@buntingmagnetics.com
Telephone: +44 (0) 1527 65858
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