How to Size your Protector Metal Detector

Determining the proper height and width of your metal detector ensures that your application is getting the best possible sensitivity; both height and width play critical roles in sensitivity and ease of installation.

The Protector metal detection system is designed to fit rails utilizing standard CEMA-approved rollers. In most instances, the detector will drop directly between the rails and no modification is required other than the drilling of mounting holes

New Conveyor Belt Metal Detector Installation
Protector HD Metal Detector Installed on Conveyor Belt

Installing the Protector on a new conveyor system.

However, due to the removable endplate, the belt does not have to be removed to install on an existing conveyor system.

Protector Metal Detector with endplate detached ready for install

Metal Detector Aperture Widths

With that in mind, the Protector HD Metal Detector is built specifically to standard belt widths, and the aperture width of the detector is always 6 inches greater than the belt width. This provides 3 inches of space on each side of the belt to prevent unwanted contact with the metal detector.

Metal Detector Aperture Heights

Determining aperture height is a bit more complicated, as it depends upon variables that are outside of the physical constraints of the metal detector and conveyor. When determining the aperture height of your Protector HD, the following must be considered:

  • Trough angle of the belt
  • Lump size of the product
  • Burden depth of the product
  • Bulk Density of the product
  • Sensitivity specification

Let’s take a closer look at some of these.

Trough Angle

When a belt is troughed, it adds height to the dimension of the belt. This is a constant, so the chart below will provide you with belt heights based on the troughing angle.

Trough Angle Chart for Metal Detector Sizing

Burden Depth

Burden depth is also considered a User Variable – it is determined by the user – but plays an important role in determining the aperture height of the metal detector. In most instances burden depth can be determined by simply measuring the depth of the product at the center of the belt. In the case of new applications, burden depth can be calculated using the following:

  1. Conveyor belt width in inches
  2. Conveyor belt speed in feet per minute
  3. Feed rate in tons per hour
  4. Bulk Density (specific weight) in pounds per cubic foot (see Bulk Density chart)
  5. Feed Capacity (ft3 per hour) : Tons per hour ÷ bulk density x 2000 = ft3/hr

Formula to calculate Burden Depth in inches:

Burden Depth Calculation for Metal Detector Sizing
Dimensions for Metal Detector Sizing

Calculating Aperture Height

To calculate the aperture height of your metal detector, several factors must be considered.

  • Is your burden depth + lump size larger than your trough angle height?
  • Is there belt sag as a result of heavy burden on the belt?
  • Do I have a specific sensitivity specification?

If your lump size + burden depth value is less than your trough height, use trough height plus 4” to determine your aperture height.

Dimensions for Metal Detector Sizing when your burden depth is lower than your trough height

If your lump size + burden depth value is larger than your trough height, use your lump size + burden depth value plus 4” to determine aperture height.

Available Aperture Heights

The Protector Metal Detector is available in the following standard aperture heights (six-inch intervals): 12”, 18”, 24”, 30”, 36”, and 42”. Please contact our team if your height requirements are smaller than 12” or larger than 42”.

After determining your required aperture height, match your number to the closest available aperture height. The shorter the aperture height, the more sensitive the metal detector will be. If sensitivity is critical, please contact us for a review of the application and a quote.

Get the Right Size Metal Detector for Your Application

Advanced Detection Systems’ Protector HD metal detection system is rugged and reliable but to get the best detection sensitivity you need the right size metal detector. Having the proper height and width will also ensure a simple installation. To discuss your specific application needs and for help determining the correct aperture height or width for your metal detector, give us a call at call at 414-672-0553 or email us at Our team can also assist you with a custom metal detection solution for your specific application.

© 2023 Advanced Detection Systems, Inc.                            (414) 672-0553

What Are Metal Detector False Trips & What Causes Them?

Metal detection is crucial to operation for a number of industries. Our metal detectors are used to ensure product purity, protect consumers and protect expensive equipment; making accurate, consistent and reliable detection extremely important. However, when your industrial metal detector has a false trip, production can come to a standstill, product can be unnecessarily wasted, and your profit margin may begin to narrow. Read on to learn what metal detector false trips are, their possible causes and how to prevent them to ensure you are getting the best possible metal detection for your application.

Industrial Metal Detector Three Coil Design

What is a metal detector trip?

Industrial metal detector heads are built around a balanced coil.  When metal moves through the metal detector aperture it disturbs the coil balance causing what is commonly referred to as a trip.

What is a metal detector false trip?

If a trip occurs when no metal is present in the metal detector aperture this trip is referred to as a “false trip”.

What causes metal detector false trips?

False trips create unnecessary product waste, downtime, and lost profits. If your industrial metal detector is giving you false signals, check for these common issues.

An unbalanced coil

Even though today’s metal detectors are equipped with technology that maintains coil balance it is possible the coil can become unbalanced if the metal detector is physically damaged.  False trips can be caused by a damaged, unbalanced coil.

Moving metal within the metal free zone of the metal detector head

Metal Free Zone of Metal Detector Conveyor Head

An electro-magnetic field is created inside the detector’s enclosure; however, some field emanates out of the aperture on both sides and forms the metal free zone (“MFZ”).  Generally, the practical size of the MFZ is 1½ times the (smaller) aperture dimension, and no metal should be allowed in this area.  Large moving metal should be kept 2 times away.  Special metal detection systems are available for applications which demand a substantially reduced MFZ. 

Conveyor with proper non-metallic side rails

Conveyor with conductive metal side rails

Ground Loops

Two pieces of metal making intermittent contact in the vicinity of the metal detector will cause false trips. Loose conveyor components touching each other, and loose nuts and bolts are common causes of ground loops.

Static electricity

Static electricity is caused by friction between two dissimilar materials. A plastic conveyor belttraveling over a plastic slider bed or dry bulk product falling through a plastic tube in a gravity fed metal detection system can cause static electricity.  The discharge of static electricity near the metal detector will cause false trips. The use of an anti-static slider bed and gravity feed tube is recommended especially in dry environments. Grounding all material handling equipment, at multiple points, prior to the metal detector will dissipate the static by giving it a path to ground.

Increased product effect caused by additional conductive product

Some products are conductive.  Warm, salty, and wet product like pickles are quite conductive and will cause a balanced coil to trip.  Metal detectors are equipped with Auto-learn features that assist the operator with automatically adjusting the metal detector’s sensitivity to ignore the conductivity of the pickles while still detecting metal particles.  This approach requires the conductivity of the pickles passed through the detector be consistent. If, for instance, two jars of pickles are presented to a metal detector set up to inspect one jar at a time, the conductivity of the additional jar of pickles will trip the metal detector.  This is considered a false trip.

Increased product effect caused by a change in the orientation of conductive product

Conductive product will present less product effect to the metal detector with the narrowest dimension leading through the metal detector aperture instead of the long dimension due to the reduced cross section of the product in the detector aperture at a given moment. 

Length leading conductive Product Passing through Food Metal Detector
Width leading conductive Product Passing through Food Metal Detector

Optimal length leading orientation

Width leading orientation

Best possible detection levels can often be achieved if the orientation of conductive product is controlled.  But if the detector sensitivity settings have been established based on the narrow dimension of conductive product leading and the product being inspected is presented with width leading, the additional conductivity of the product may cause a false trip.

Radiated noise

Transmitters of radio frequencies and motors with variable frequency drives operating near the metal detector radiate noise that can cause false trips. Anything that creates a frequency equal to the frequency at which the metal detector operates will interfere with the operation of the detection system.

Electrical line spikes and dips

Most of today’s industrial metal detectors are equipped with power supply hardware and electronics that effectively condition incoming power to avoid false trips caused by spikes and dips in plant electrical power service. But significant power fluctuations of 10% or more may disturb the metal detector coil balance enough to cause false trips.

Metal Detection System with Contaminated Conveyor Belt

Metal contaminant imbedded in the conveyor belt

If a metal contaminant becomes imbedded in the conveyor belt it will be carried by the belt through the metal detector and cause a false trip.  The belts used in conveyor mounted metal detection systems are designed to be easily removed from the conveyor frame facilitating thorough cleaning of the top and bottom of the belt.

False Trip Support for Metal Detection Systems

For over 30 years, Advanced Detection Systems has developed a reputation as a quality metal detection equipment manufacturer for many industries with diverse metal detection needs. With experienced engineering, manufacturing and sales people working together in our Milwaukee, WI facility, we can provide expert advice and aftermarket metal detector support to customers needing assistance with their industrial metal detection system. If you are experiencing an issue with false trips and need assistance, don’t hesitate to reach out. Give us a call at call at 414-672-0553 or email us at and we’ll see what we can do to get you metal detection system that provides the best sensitivities possible, eliminates downtime and ensures product purity.

Benefits of the Protector Metal Detection System’s Product Monitor Feature

The SurroundScan Protector series of industrial metal detectors have a unique Product Monitor feature that Displays real time product signals. It is one of Advanced Detection Systems’ core technologies that allow our metal detection systems to provide superior detection of ferrous, non-ferrous and stainless-steel tramp metal necessary to ensure product purity and protect your processing equipment. Learn more about this core technology, how to use it and the benefits it provides.

Protector HD Metal Detector

Detect harmful tramp metal while ignoring metal that is harmless.

The Product Monitor is software included in the touchscreen of all Protector series metal detectors.

The Product Monitor gives users real-time feedback on the signal levels of the product and metal contaminants passing through the metal detector.

The signal levels shown on the Product Monitor can be used to establish the metal detector’s sensitivity settings required to detect harmful tramp metal while ignoring metal that poses no threat to processing equipment.

Protector Metal Detection System’s Product Monitor

Using the metal detector’s Product Monitor feature.

Upon initial setup of a Protector metal detector, the AutoLearn program can be used to automatically set the detector’s sensitivity so product is allowed to pass through the detector while metal contaminants are still detected.

But what happens if there are some metal contaminants that you do not want the metal detector to detect because they will not damage downstream processing equipment?

The Protector’s unique Product Monitor will show you the real-time difference in signal levels between the metal contaminants you do want to detect and those you do not want to detect.

Based off of the difference in signal values shown on the Product Monitor, the operator can adjust the metal detector’s sensitivity accordingly so it allows the metal contaminants with a smaller signal value to pass through while still detecting the contaminants that have a larger signal value.

Conveyor Belt Metal Detector at Stone Quarry

The Product Monitor feature simplifies Metal Detection.

Take the guesswork out of metal detector sensitivity adjustments. The Product Monitor feature on our Protector metal detectors allows production crews to efficiently remove harmful tramp while avoiding costly down time caused when small pieces of harmless metal lead to detections that occupy workers and shut down production.

Detect It

Detect Harmful Tramp Metal

Ignore It

Get the Right Metal Detector for Your Application

Advanced Detection Systems’ Protector series of rugged, industrial metal detectors provide reliable metal detection of ferrous, non-ferrous and stainless steel tramp metal.  The Product Monitor feature provides real-time monitoring so your metal detector can be set to the right level of detection to protect your processing equipment without slowing down production.  To discuss your specific application needs and how our metal detector’s Product Monitor feature will benefit you, give us a call at call at (414) 672-0553 or email us at

Metal Detector Verification Service… What is it? Why & How Is It Conducted?

Metal Detection Validation touchscreen setup

Metal Detector Verification is a crucial and most often required part of ensuring the purity of your product and protecting your business. Read on to learn more about metal detector verification, how it’s conducted, how it differs from validation and why it’s so important to your business.

What is Metal Detector Verification?

Food production facility metal detectors are tested multiple times during production to ensure they are always properly detecting and rejecting contaminated product as required by the owner’s critical control point documentation. The daily tests and record keeping are usually performed in-house by quality control personnel. This confirmation of a metal detector’s ability to meet the standards set forth by its owner is referred to as Validation.

Verification of those tests are done by an outside company that visits your plant and performs the same daily tests the metal detector’s owners do while also ensuring proper testing practices are used. If the metal detector passes the tests as required by the equipment owner, just like it does during the production run tests, the detector is considered verified. The test result records done by the food company on a daily basis are verified to be accurate based on the same results being achieved when an outside company performs the same tests. If the outside company is not able to get the metal detector to meet the specified test results, the detector cannot be verified and the metal detector’s settings or methods of testing need to be reviewed and corrected so it can meet the standards required by the owner’s documentation.

Metal detection for bagged product on a conveyor

Why Metal Detector Verification & Documentation?

Verification service is conducted to confirm and document the metal detector in service is detecting Ferrous, Non-Ferrous and stainless steel particles of a specified millimeter diameter without false tripping on the product in production. If the metal detection system in service has an automatic reject device the rejection of the detected metal particle is also confirmed and documented.

Sample of metal detection validation certificate

Metal Detector Verification & Food Safety Plans.

Documented Metal Detector Verifications are key components of a food processors food safety plan. Regularly scheduled Verifications conducted by a 3rd party help ensure the purity of a company’s product and provide protection of a company’s brand. Verifications are required by government regulations, auditors, Hazard Analysis Critical Control Point (HACCP) plans and most food retailers.

How Is Metal Detector Verification Service Conducted?

Metal Detector Verifications are typically scheduled annually and conducted by metal detector manufacturers and their Certified representatives. Verification is conducted by passing Ferrous, Non-Ferrous and Stainless Steel certified test wands under normal production conditions through the center of the metal detector aperture a minimum of three times each. Successful detection and rejection of the test wand and product are documented and Verification stickers are applied to the metal detector by the person conducting the Verification.

ProScan Max III touchscreen for validation process

Have Your Metal Detection System’s Performance Verified by ADS

Advanced Detection Systems conducts Verification on any make/model metal detection system or equipment. Our HACCP (Hazard Analysis and Critical Control Points) certified factory service technicians and certified local representatives conduct metal detector verifications on-site and are compliant with most QA programs, audits, HACCP and GMP (Good Manufacturing Practices) standards. Contact us at 414-672-0553 or to schedule Verification services you need today!

Metal detection product testing cards

Metal Detector Product Testing

Metal Detection test wand spheres

Metal detector product testing can ensure that you are investing in the best possible metal detector for your application. Read on to learn more about how metal detector product testing is done and its benefits.

Metal detection test wands for product testing

How Is Metal Detector Product Testing Done?

Metal Detector product testing often offered at no charge by metal detector manufacturers is a valuable step to take when choosing the best and most reliable metal detection system for your specific application. Durning a metal detector product test, samples of your product are sent to the metal detector manufacturer who will use them in their test lab to prepare a Sensitivity Guarantee for your product in the specified metal detector aperture size. For example 1.5 millimeter Ferrous metal, 2.0 millimeter Non-Ferrous metal and 3.0 millimeter Stainless Steel.

Cakes on a metal detection conveyor

Why Product Test A Metal Detector?

Product testing a metal detector before purchasing can be extremely beneficial, especially for the food processing and packaging industry. Some of the benefits metal detector product testing can provide include:

To determine the metal detector model & type required to meet your sensitivity requirement.

In some case food processors are required to achieve a detection level specified by their customer. In that case product testing can be done to confirm that the metal detection equipment you are considering buying will meet your customer’s sensitivity requirement

To establish a metal detector sensitivity specification for a new application.

When a food processor is adding new packaging or a production line, product testing can be done to establish the best possible detection level.

ProScan Max III sensitivity settings touchscreen

To determine the effect of product orientation and aperture size on detection levels.

When determining the production process that optimizes metal detection levels product testing helps food companies determine the specific metal detector aperture size and product orientation that will optimize metal detector detection levels.

Metal Detection Product Orientation Narrow Side leading Cheese

To obtain a written metal detector Sensitivity Guarantee

In many cases food companies are primarily interested in using a metal detection system that will provide the best possible detection levels in their application. Product testing can be done to establish a Guaranteed detection level.

Metal detector product testing simplifies Start-Up

When a food company takes delivery of a new metal detection system the start-up of the metal detector revolves around running product and confirming the metal detector performance meets the required detection levels. Product testing early in the purchasing process simplifies and facilitates a trouble free start-up free of surprises.

Metal Detector Product Testing from ADS

Use our free product testing service to ensure that you are investing in the best possible metal detector for your application. Advanced Detection Systems product testing service is conducted promptly at our factory lab in Milwaukee, WI. Use our metal detector product testing service and receive a sensitivity guarantee! For more information or to schedule a metal detector product test, call us today at 414-672-0553 or email us at

Metal detection test wands spheres for product testing

Product Effect & Metal Detection

Product effect on metal detection, Conveyor with cheese

One of the more important factors in determining what metal detector is best for your application is your product and the effect it has on the metal detector. Products have varied levels of conductivity and the conductivity of your product will influence the signals picked up by the metal detector. We call this Product Effect.

What is Product Effect?

The term Product Effect is used to describe the signal generated by product as it passes through the metal detector. Metal detectors measure the conductivity of things that pass through their aperture. The conductivity of a product is determined by its ingredients. Products that contain salt, fat, minerals, and moisture will be more conductive and generate more product effect than dry products that are less conductive.  The signal from these conductive products is accommodated by operating the metal detector at a specific frequency and sensitivity settings that allows the conductive product to pass through the metal detector undetected while still detecting the high-intensity conductive signals of Ferrous, Non-Ferrous and Stainless-Steel contaminants.  

Touchscreen metal detection product monitoring

Accommodating for Product Effect in Metal Detection

The adjustment of the metal detector made to accommodate product effect, (referred to as phasing out the product) leads to reduced metal detection levels in conductive products when compared to the detection levels achieved in dry products that have little or no product effect. Given the existence of product effect and the need to achieve the best possible metal detection levels, dry products have come to be known as easy metal detector applications while conductive products are considered challenging applications. While this challenge is being met by the continued development of metal detector technology that improves metal detection levels in conductive products, it is possible to enhance detection levels by presenting conductive product to the metal detector in ways that reduce the impact of its Product Effect on metal detection levels.

Width leading product orientation for Metal detection dairy. Cheese.

How to Improve Metal Detection for Conductive Product

Companies processing conductive products such as cheese, pickles, and marinated meats often consider the following methods of improving metal detection levels when developing their process for producing the product.

  • Identify Best Possible Product Orientation
  • Control Product Orientation
  • Control the Consistency of Moisture Level, Product Temperature, Package Size, and Weight.

The Value of Metal Detector Product Testing

The product testing service offered by metal detector manufacturers can be used up front to determine the conductivity of your product and the benefit of controlling product orientation, temperature and moisture level to achieve the best possible Ferrous, Non-Ferrous and Stainless-Steel detection levels.

Get the Best Metal Detector for your Application with ADS

Use Advanced Detection System’s free product testing service to ensure that you are investing in the best possible metal detector for your application. Product testing is conducted promptly at our factory lab in Milwaukee, WI and will provide you with a Metal Detection Sensitivity Guarantee indicating the optimal ferrous, non-ferrous and stainless steel detection levels for your specific products in the metal detector aperture size you will be using in your process.

Call us today to get started 414-672-0553 or email us at

Why Advanced Detection Systems has the Competitive Advantage with the Protector HD Metal Detectors

ADS Protector HD Metal Detector

When considering Advanced Detection Systems as your metal detector supplier keep in mind that metal detection for industrial applications is our only business. This means that our engineering, service and sales office staff members have been assisting people with industrial metal detector applications day after day for more than 30 years and have become experts. This expertise means we are well qualified to help you choose the metal detector that best meets your specific needs. 

Advantages of The Protector HD Metal Detector

Advanced Detection Systems SurroundScan Protector HD Metal Detector

The Protector HD metal detector’s heavy duty construction provides long term use in tough environments such as rock quarries, mining and recycling. The Protector HD’s steel construction protects the transmit and receive coils from damage cause by impact or the outdoor elements. The remnants of damaged, lightweight metal detectors fastened to high production conveyors in quarries are a somewhat common sight. The cost and time required to put the damaged “lightweight” unit back in service commonly leads to delays in getting the metal detector repaired and back in use. 

Defend Processing Equipment with Superior Tramp Metal Detection

Advanced Detection Systems Protector HD Metal Detection System in Operation

The Protector HD is commonly used to defend processing equipment such as granulators, crushers and grinders from damage caused by tramp metal that has found its way into the product stream. The metal detector has a transmit coil in the top tank and a receive coil in the bottom tank. The transmit and receive coils are balanced at a low frequency. A piece of tramp metal passing through the detector disturbs this balance, tripping the detector and stopping the conveyor or actuating a downstream reject device. The Protector HD’s unique digitally balanced coil and dual channel operation provide outstanding reliability and consistency. Metal detectors lacking state of the art digitally balanced transmit and receive coils may drift out of balance leading to inconsistent performance and the need to be re-balanced. 

As an engineering driven industrial metal detector manufacturer Advanced Detection Systems is constantly enhancing the Protector HD for improved performance, ease of use and reliability. Examples are its state of the art power supply and noise protection eliminating what are commonly referred to as nuisance trips. Most metal detectors in quarry applications are set up to stop the conveyor when it is tripped by metal. When this happens, the operator goes to the detector to locate and remove the tramp metal that’s been detected. Lacking a state of the art power supply voltage spikes and dips on the electrical circuit running the metal detector can cause the detector to trip and stop the conveyor. It’s referred to as a nuisance trip because the operator must visit the detector to search for metal that’s not present and then re-start the conveyor. 

Advanced Metal Detection Sensitivity

Protector Metal Detector AutoLearn feature

There is conductive ore in some mined material that can trip the metal detector. The Protector HD has adjustable sensitivity settings enabling it to ignore the signal from conductive material while at the same time detecting the larger signal from tramp metal that could damage a secondary crusher. Rather than having to manually adjust the sensitivity setting to accomplish this the Protector HD has an Autolearn feature that when used while product is passing through the detector automatically sets the detector sensitivity setting. Lacking this feature operators are left with trial and error to set the metal detector sensitivity settings to ignore conductive product and still detect the smallest size tramp metal that could damage their processing equipment. 

Protector Metal Detector Product Monitor feature

Sometimes the specific metal that must be detected changes and requires a change of the metal detector sensitivity settings that have typically been used. In this case the Protector HD’s Product Monitor feature can be used to re-adjust the detector. With product passing through the metal detector the product monitor can be used to display the real time signal value from the product and the target metal that must be detected. These real time signal values can be used to re-set the sensitivity settings as needed. Lacking these real time values adjusting the metal detector sensitivity setting under these circumstances can be a guessing game. 

Optional Metal Detector Accessories

Protector Metal Detector Total System Configuration with Splice Sensor and Metal Marker Accessories

“Spliced” belts are common on conveyors in quarry, mining and recycling metal detector applications. Advanced Detection Systems offers an optional Splice Sensor accessory for the Protector HD metal detector and the hardware package to properly mount it on the conveyor frame. The splice sensor installed on the conveyor upstream of the Protector HD detects the belt splice as it passes by and sends a signal to change the Protector to a “splice setting” that allows it to accommodate the signal from the splice without tripping. At start-up the Protector’s unique “splice learn” touchscreen software is used to determine the splice signal and automatically set the splice sensitivity setting and duration for the time needed to allow the splice to pass. 

Metal Marker Accessory by Advanced Detection Systems

In applications with conveyor belts wider than 4 feet and burden depths exceeding 12” (in other words a lot of material) the Advanced Detection Systems unique Metal Marker metal detector accessory can be used to assist operators with locating the tramp metal that has been detected. Upon “detect” the metal marker automatically discharges a brightly colored, highly visible plastic baton and chain in the vicinity of the tramp metal. The baton with orange plastic chain is easily re-loaded into the marker and eliminates the ongoing maintenance associated with the use of paint and spray dye markers. 

The Protector HD with password protected intuitive menus used in conjunction with Advanced Detection Systems proven splice sensor and metal marking devices add up to a state of the art easy to use and reliable system for detecting tramp metal and preventing costly repairs and down time. 

Make ADS Your Industrial Metal Detector Supplier

Advanced Detection Systems’ engineers are experts in industrial metal detection. Our unique approach to metal detection ensures product purity and defends processing equipment. The Protector HD is built to your application specifications and sized to meet your specific needs. Get started today by calling us today at 414-672-0553!

David Smith 
©Advanced Detection Systems, 2023 

What Factors Affect the Best Possible Detection Levels?

ProScan Metal Detector Display Menu

Advanced Detection Systems manufactures metal detectors designed to provide reliable, easy-to-use and consistent metal detection. Whether you need to ensure product purity or defend processing equipment, getting the best possible metal detector for your application is of utmost importance. Part of ensuring optimum sensitivity is understanding the factors that affect metal detection levels.  

Types of Metal 

Certified 2.50 mm Non-Ferrous Test Piece on Product

When considering factors that affect the best possible detection levels keep in mind that metal detectors are used to detect particles of Ferrous, Non-Ferrous (aluminum, brass, copper) and Stainless Steel. The accepted method of stating the detectable metal in a particular application is in millimeter spheres. The metal detector’s balanced transmit and receive coils are disturbed by conductivity. Since Ferrous metal is more conductive and magnetic than Non-Ferrous metal or 316 Stainless Steel a metal detector will detect smaller particles of Ferrous than Non-Ferrous or 316 Stainless Steel. Plant managers at food production facilities document the size metal that must be detected by their metal detectors. For example, a metal detection specification of 1.5 mm Ferrous, 1.8 mm Non-Ferrous and 2.0 mm 316 SS reflects the difference in detection level for Ferrous metals, Non-Ferrous metal and Stainless Steel. 

Aperture Size 

ProScan Max III Metal Detector’s Aperture

The metal detector’s aperture size is a determining factor in the metal detector performance because the best possible detection level declines as the aperture size increases. The size of the metal detector aperture is determined by the largest package or portion of product passing through the detector at a given time. For instance, a 2 lb package of ground beef measuring 5” wide x 7” long x 2.5” high with the narrow dimension leading will require an aperture 4” high and 8” wide if the ground beef is being conveyed on a 6” wide belt. 


The conductive characteristics of the product known as “Product Effect” also affect the best possible detection level because products that are moist, warm or hot and contain salt or fat can be quite conductive. The quantity or orientation of a conductive product also changes the product effect presented to the metal detector. 

Metal detectors have an Auto Learn feature that analyzes the conductivity and automatically adjusts the metal detector to accommodate the product effect while detecting metal that is in the product. Given the importance of achieving the best possible detection levels food processors often have their product tested by a metal detector manufacturer to determine the best possible detection levels based on their specific aperture size and product characteristics. Lacking product testing the best possible and reliable detection levels are often established at the in-plant start-up of the metal detection system using the metal detector’s AutoLearn feature. 

ProScan Metal Detector Product Setup Menu Touchscreen

What Metal Detectors Achieve the Best Possible Detection Levels

Given these factors that are known to affect the best possible metal detection levels food processors who produce non-conductive products and are able to use metal detectors with small apertures are expected to achieve better metal detection levels than those producing conductive products and having to use detectors with larger apertures. 

Get the Best Metal Detector for your Application

Discuss your application with an Advanced Detection Systems metal detector expert today to determine what is the best configuration for your application. We also offer a free product testing service, providing a Sensitivity Guarantee to indicate the optimal detection levels for your products. Call us today to get started 414-672-0553 or email us at

David Smith 
©Advanced Detection Systems, 2023