A guide to validating and verifying the metal detectors at your food production site, highlighting the importance of ‘prevention before detection’.

If you are exploring the benefits of Detectable Equipment, it is likely that you have one or more metal detectors at your food production site.

In the following article, you will find guidance on validating and verifying this equipment. This guide also covers the basics of routinely testing your detector(s), finding the right metal detector frequency, and embracing the principles of ‘prevention before detection’ with our Detectable Pens and Markers.

Validation is the process of proving your metal detector is suited to its intended application.  

The validation of your equipment will need to take place when you first install your metal detector, and it will need to be repeated if you make any significant updates or enhancements. 

If your site is audited by BRCGS, you will need to pay close attention to Clause 4.10.3.1, Issue 9 of the Global Food Safety Standard. It asks that your metal detector incorporates one of the following: 

• An automatic rejection device for continuous in-line systems 
• A belt stop system with an alarm 
• In-line detectors which identify the location of the contaminant  

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Verification is the ongoing process of proving your metal detector is working as it should be.  

The frequency of your verification activities will be dependent on the risk levels associated with your products and processes. However, it is typical for sites to verify their metal detectors every 6-12 months.  

Your site’s HACCP Team may decide to adjust the frequency of verification and introduce additional activities in response to a specific food safety incident, stricter audit requirements, or a rising trend in customer complaints. 

During the verification process, you will need to ensure: 

• Both the detection and rejection mechanisms of the metal detector are working effectively 

• The metal detector still operates in accordance with the expected sensitivity levels 

• The detector is compliant with the relevant safety standards (e.g. Issue 9, BRCGS Global Food Safety Standard)

• The metal detector isn’t incorrectly rejecting acceptable product 

Clause 4.10.3.4, Issue 9 of the BRCGS Global Food Safety Standard highlights the importance of routinely checking your metal detectors.  

Your site’s HACCP Team will need to decide on the frequency of these tests. Some sites carry out this process at the start and end of every production period, with other factories testing even more regularly.   

According to BRCGS, as a minimum, testing procedures should include the “use of test pieces incorporating a sphere of metal of a known diameter selected on the basis of risk. The test pieces shall be marked with the size and type of test material contained.”  

The test pieces used at your site should reflect your metal detector’s sensitivity to ferrous, non-ferrous, and stainless steel. Once selected, it is also good practice to place the relevant test piece close to the least sensitive area of your metal detector (usually the centre). If possible, it should sit inside a clearly identified product.  

When setting up your metal detector, selecting the right frequency is one of the most important decisions you can make. You will need to consider the characteristics of the product(s) you produce (e.g. dry products have a lower background signal, whereas wet products create a much higher signal and are more likely to trigger a sensitive detector). You will also need to consider key factors such as the angle at which your products pass through the detector, the potential impact of your packaging, the aperture of the equipment, and the speed of the detection process.  

For a complete guide to setting the frequency of your detector, click the button below. 

Although it is important to validate, verify, and routinely test the metal detectors at your site, it’s vital that driving standards in metal detection doesn’t lead to complacency in other areas. 

The best way to avoid this? Prevention before detection. 

Retreeva Global equipment is metal and x-ray detectable. However, we understand the prevention of foreign body incidents needs to start long before your products are passed through a detector.  

That is why Retreeva pens offer the following design features: 

• Made from shatter resistant polymers to prevent your pens from breaking into small pieces that are unlikely to be picked up by your metal detectors.

• Made from the minimum number of parts, eliminating the unnecessary risks posed by surplus and small components.   
• A unique cartridge suspension system, so no need for a high-risk, metal spring.