Metal Detector Specifications: Sensitivity, IP Rating, and What to Check Before You Buy

Metal detector specification sheets tend to list a lot of numbers — frequencies, IP ratings, opening dimensions — without explaining which ones actually matter for your line. Here's a practical walkthrough of what to check, split by configuration.

Confirm the Configuration Before Anything Else

Gravity-fall detectors inspect material as it free-falls through the aperture, before packaging — the right fit for fertilizer, oleochemical, food ingredient, chemical, and plastics operations handling bulk product upstream of bagging. Inline conveyor detectors inspect finished, sealed packages on a takeaway conveyor at full production speed. These are different equipment classes solving different problems — get this decision right before comparing spec sheets, because a gravity-fall unit's specs (aperture size, fall rate) aren't directly comparable to an inline unit's (belt speed, opening width/height).

Inline Conveyor Specifications — What ENZAC Supplies

ENZAC's inline conveyor detectors are premium-class, rated at 30% better sensitivity than entry-level tuned detectors through advanced drive electronics and optimised coil geometry. Full specification:

What Each Spec Actually Means for You

Multiple selectable frequencies matter because detection sensitivity varies by product — a single fixed-frequency unit is tuned as a compromise across whatever passes through it. Three selectable frequencies let the same unit be re-tuned per product rather than accepting reduced sensitivity on some SKUs.

IP rating should match your wash-down regime, not just your general environment. IP69K is washdown-rated for high-pressure, high-temperature cleaning — standard in food and pharmaceutical plants with daily sanitation cycles. IP65/66 suits dry bulk handling where washdown isn't part of the routine. Specifying IP69K where it isn't needed adds cost without benefit; specifying IP65 where washdown is actually required risks premature failure.

Product memory (200 products) matters most on mixed-SKU lines. Without it, sensitivity settings drift or get manually re-tuned inconsistently every time the product changes — exactly the audit failure mode covered in ENZAC's guide to failed metal contamination audits. With stored product memory, the same calibrated setting loads automatically per SKU.

Opening width/height needs to match your actual package dimensions with clearance — oversizing the aperture reduces sensitivity (more empty space around the product means more "noise" in the detection field), while undersizing obviously won't fit your product at all.

What's Missing From a Bare Spec Sheet

Two things a spec sheet alone won't tell you, but should be part of your enquiry:

What catches what a metal detector can't. Even a premium-class detector has a sensitivity floor — sub-threshold metal dust and fine fragments won't trigger it. For gravity-fall applications in plastics, food, and pharmaceutical production, pairing the detector with a grate magnet separator upstream closes that gap; the magnet catches what's below the detector's own tolerance.

What happens after a detection. Auto-reject mechanism type (pneumatic pusher, air-blast, or divert conveyor) should be specified based on your line speed and product weight — not defaulted to whatever's cheapest. On inline conveyor lines, pairing the detector with a checkweigher and rejector gives you a combined contamination-and-weight-tolerance last line of defense before the product ships.

Review the full Metal Detector equipment page for gravity-fall and inline conveyor configuration details.