How Often Should You Validate Your Metal Detector? (SQF & BRCGS Requirements)

2026-10-14 · Jordan Wheeler

"How often do we need to validate our metal detector?" is one of the most common questions we hear from Utah food manufacturers. The honest answer is that there are really two schedules to think about: how often your team verifies the detector, and how often it gets a full validation. Auditors expect both.

Verification vs. validation: two different schedules

Verification is the routine check your operators do with test pieces to confirm the detector is still working right now. It's quick, it happens often, and it's done by your own team.

Validation is the deeper, documented proof that the detector can find the contaminants your food safety plan names, in your real products, at your real line speeds, and that the reject system removes them. It's done less often, usually by a qualified third party, and it produces a formal report.

If validation is the proof that the system works, verification is the evidence that it kept working between validations.

What SQF and BRCGS expect

Neither SQF nor BRCGS sets a single calendar date that applies to every plant. Both expect you to decide your frequencies based on risk, write them down, and follow them.

• SQF (Code Edition 9, Module 11.7.6, detection of foreign objects) expects detection equipment to be in place where it's needed, checked at a defined frequency, and supported by records and corrective actions.
• BRCGS (Issue 9, Section 4.10.3, metal detectors and X-ray equipment) expects documented test procedures, test frequencies based on risk, and fail-safe systems, along with clear actions when a test fails.

In practice, that means an auditor will ask three questions: What frequency did you choose? Why? And can you show me the records?

Typical verification frequency

Most plants verify their metal detectors:

• At start-up, before production begins
• At regular intervals during production (many plants check every hour or two)
• At every product or SKU changeover
• After any maintenance, adjustment, or stoppage
• At shutdown, at the end of the run

The interval you choose matters because of what happens when a check fails. If the detector fails a check, you'll need to hold and re-inspect everything produced since the last successful check. The longer the gap between checks, the more product is at risk.

Typical validation frequency

For full validation, the common practice is:

• At least once a year for every detector
• When a detector is installed or moved
• After major repairs, part replacements, or software updates
• When you add a new product, packaging type, or product temperature
• When line speed changes significantly
• When a customer or certification body requires it

Higher-risk operations, such as plants supplying sensitive customers or running products with strong product effect (wet, salty, or frozen foods), often validate more frequently. That's where annual service contracts with twice-yearly, quarterly, or monthly visits come in.

How to justify your frequency

Auditors don't just want a number. They want your reasoning. When you set or review your frequencies, consider:

• Your product. Wet, salty, dense, or temperature-variable products make detection harder.
• History. Have you had failed checks, false rejects, or customer complaints?
• Upstream controls. Magnets, screens, and sieves reduce risk before the detector.
• Your customers. Some retailers and brand owners specify their own frequencies and test piece sizes.
• Consequence. How much product would you need to hold if a check failed?

Write this down in your food safety plan. A short paragraph explaining why you chose your frequencies goes a long way in an audit.

What happens at a validation visit

A proper validation goes well beyond waving a test card. At Wheeler Food Safety, every validation includes ferrous, non-ferrous, and stainless steel test pieces at the leading edge, center, and trailing edge of your product, three passes in a row each, plus checks of the reject system and every fail-safe. If something fails, we adjust and retest until the system passes, and record exactly what was changed.

Read the full walkthrough: What Happens During a Metal Detector or X-Ray Validation.

The bottom line

Verify often, validate at least annually, and revalidate whenever something significant changes. Most importantly, document why you chose your frequencies, because that reasoning is what auditors look for.

Learn more about our metal detector validation for Utah food manufacturers.