4 replies to this topic

[dekel poliva]

We have magnets in-line. When inspector comes to test the magnets he gives a report with gauss measurments.

i am looking for a chart that could trnaslate distance,gauss and material so i could use it as a validation for the HACCP.

How do you validate your magnets without contamination the line with metals?

 

[GMO]

Material is obviously only ferromagnetic metals or metal alloys with a significant ferromagnetic quantity. It won't work on all metals let alone all materials. The efficacy will depend on size, location of the magnet, weight of the contaminant. I would never use a magnet as a CCP because you cannot directly say "it will pick up xx mm size of mild steel" because it depends how far away it is from the magnet, is the magnet over or under the flow? Are there other materials between the contaminant and the magnet? How often are they cleaned and checked (as they are notorious for having debris build up and dump back in.)

 

Rather than think of "what does this magnet remove?" I'd flip it. If anything, it's verification of other processes you have in place including PPMs, hygiene clearance and I'd always have a metal detector after it. So while it's possible some metals will be removed by a magnet, it's not certain (and not even close to certain if I'm honest). BUT what it can do is give you an early warning that something is wrong upstream. 

[SHQuality]

We have magnets in-line. When inspector comes to test the magnets he gives a report with gauss measurments.

i am looking for a chart that could trnaslate distance,gauss and material so i could use it as a validation for the HACCP.

How do you validate your magnets without contamination the line with metals?

I agree with GMO. Metal detectors are notorious for harbouring build up of metal debris. I would expect that when the magnets were originally installed, it was done based on the experience of the magnet's manufacturer. I would look for that validation report and see what it actually validates in your specific environment.

 

The magnet is not going to work as a CCP, but it will still contribute to the overall management of hazards if you can find out its effectiveness against ferric contaminants.

[PQEdwards]

Some great comments above and in ideal world metal detection or X-ray would be preferable but my experience is that the food ingredients we manufacture are in large bulky containers where this impractical due to detection capability. Regular inspection and cleaning of the magnets and trending of the levels and type of material recovered has served my organistion through several rounds of GFSI certification. The caviat being that the equipment materials of construction are largely capable of being captured by magnets. Usually your magnet supplier will specify the optimum distancing between magnet elements (assuming you are using grid magnets) based on the flow properties and flow rates of your material. Regular strength checks (Gaus strength) against the original specified strength should serve to provide continued verification of fitness for purpose. You could consider using passing metal contaminants across you magnet (e.g. ball bearings) and measure the capture efficiency.  

[SHQuality]

I agree with GMO. Metal detectors are notorious for harbouring build up of metal debris. I would expect that when the magnets were originally installed, it was done based on the experience of the magnet's manufacturer. I would look for that validation report and see what it actually validates in your specific environment.

 

The magnet is not going to work as a CCP, but it will still contribute to the overall management of hazards if you can find out its effectiveness against ferric contaminants.

I can no longer edit my previous post, but of course, it should have read: "Magnets are notorious for harbouring build up of metal debris."

Edited by SHQuality, 06 January 2026 - 10:22 AM.