Flow-Through Metal Detectors

Flow-Through Metal Detectors

For liquids or products being pumped through the production process, TDI Packsys offers flow-through metal detection systems. The flow-through metal detector is a robust, high performance, operator friendly system suitable for liquid and semi-liquid products. It integrates an auto-reject valve to divert contaminants from the product flow, while minimizing waste and rework. Read More
  • This field is for validation purposes and should be left unchanged.

Table of Contents


For the accurate inspection of pumped fluid and semi-fluid products, including sauces, liquids and other food products.

Standard Features

  • Proprietary, powerful automatic product identification technology suppresses even the strongest product effect, enhancing both detection sensitivity and accuracy
  • Easily integrated into most existing sealed pipe product conveyance systems
  • Optional compact design for applications with limited space
  • Food contact rated Teflon inner pipe liner withstands high temperature and pressure conditions
  • Fast, accurate rejection valve for very low product waste
  • Excellent option for both low and high viscosity products, some pure liquids to ground meat
  • Will quick couple with 3 different pipe diameters: 50, 63 and 80mm
  • Heavy duty, sanitary construction suitable for wash-down food processing applications
  • Multilingual user interface, including English, Spanish, and many other language options
  • Portable, on casters so it can be easily moved

Why We Are the Best

Inline metal detectors from TDI Packsys bring effective, reliable product inspection to your process, allowing you to stay running and maximize the safety and quality of your products. 

With various models and configurations available, you can rest assured that a metal detector from TDI Packsys will be the tailored inspection solution you’re looking for. 

TDI Packsys is with you every step of the way with the finest, most comprehensive support including operator training, annual testing, certification and calibration to ensure your system remains in complete and continual compliance with all applicable regulations. Let us find the metal detector equipment that is right for you.


Metal detectors operate on the principles of electromagnetic induction. Each system features one or more inductor coils that interact with metallic elements within a product. As shown, a single-coil metal detector uses the same principles as a standard metal detector, just simplified. A pulsing current is applied to the coil, which then induces the magnetic field shown in blue. This magnetic field envelops the area surrounding the metal detector opening, and products pass through this field during inspection.

In addition to the transmitter coil, metal detectors have receiving coils that continuously analyze the magnetic field of the inspection zone. When metal moves through the magnetic field of the metal detector, such as the coin in this illustration, the field induces electric currents (called eddy currents) in the coin. The eddy currents induce their own smaller magnetic field (shown in red), generating an opposite current that can be picked up by the receiving coil. The metal detector is then able to detect this signal from the eddy current, and will alert to the presence of metal in the inspection area.

Inline metal detection systems can detect a wide variety of metals and conductive materials, including both ferrous and nonferrous metals, and some other conductive compounds. Ferrous metals are conductive and contain iron, though many are composed of carbon or other elements combined with iron. The various types of steel are all categorized as ferrous metals. Ferrous metals are usually magnetic, and more prone to rust than nonferrous metals. Nonferrous metals are composed of elements other than iron, and include aluminum, copper, nickel, tin, brass and zinc.

All of these metals can be detected by inline metal detectors, and the exact amount of each metal needed to trigger detection depends on the conductivity of the metal, as well as the conductivity and size of the product being inspected.

Almost all types of food and beverage products can be inspected with an inline metal detector, as long as they are not packaged with any metallic material. Harvested goods, snack foods, bakery items, proteins, and frozen foods are all viable to inspect with metal detection.

However, products that are packaged with metallized foil, in metal containers, or with metallic inserts are not recommended to be inspected with metal detectors. These products will conduct the magnetic field of a metal detector in the same way that an actual contaminant would, causing either high false-reject rates (of product without contaminants), or significantly reduced sensitivities of true foreign bodies. X-ray inspection systems are the preferred method for inspecting products packaged with metallic elements, as x-ray does not rely on conductivity during inspection.

The term “product effect” describes the natural conductivity of a product, and the impact it has on a metal detector system. Product effect is observed even on products that are known to have no metal bodies in them. Because food metal detectors use conductivity to inspect for contaminants, products that are naturally conductive can trigger the metal detector as they pass through. Red meats, products with high salt or fat contents, and products with a lot of moisture all have above average product effects. These products can still be inspected using a metal detector system. However, it is important to select the right system when considering high product effects. Certain food metal detectors use multi-frequency inspection, which allows them to optimize sensitivity even on those more conductive products. RMD Series High-Configuration Metal Detectors from TDI Packsys allow the operator to modify the frequency of inspection, ensuring high-performance inspection with minimal product effect.

In some applications, product effects are simply too high, and will negatively impact inspection sensitivities with even the most advanced metal detectors. For these products, x-ray inspection systems are a perfect solution, as they do not experience product effect, and will not be affected by changes in the product.

The main difference between metal detectors and x-ray inspection systems is the methodology of how each machine inspects for foreign materials. Metal detection uses conductivity to locate stainless, ferrous, and nonferrous metals in product. X-ray inspection uses density differences between the product and foreign bodies, allowing for a far greater range of foreign material detection – use to find metal, glass, stone, bone, rubber, gasket (both metal detectable and non-metal detectable), plastic, and various other mid- and high-density items.

Some products are limited to certain inspection systems due to their composition and packaging. Products with metallic packaging, such as those with metallized foil, cannot be accurately inspected with a metal detector, and require the use of an x-ray inspection system. The best way to determine which option is best for your application is to receive a consultation or free, no-obligation validation testing. We can test your exact product on a variety of different systems using certified test cards, or foreign material samples you provide, to offer you a formal report on the capabilities and expected performance of each type of technology. At TDI Packsys, we believe validation testing on your specific products is an integral step in choosing the right system for your needs.

Spec Table

NameFlow-Through Metal Detector
Main Construction304 stainless steel (matte, smudge resistant)
Inspection Diameter53mm; 60mm; 80mm
Control PanelIntuitive LCD HMI Touchscreen
Detection Sensitivity without product

Fe Φ 0.7mm

Non-Fe Φ 1.0mm

SUS Φ 1.0mm

ProductLiquid / semi-liquid
Alarm / RejectAuto-rejection valve
Machine Weight132 lbs
Operating Environment32 – 104°F
Product MemoryUp to 100 unique programs
IP Level66 (washdown)
Parameter AdjustmentAuto or manual programming
CertificationsFDA CFR 21.1020.4 compliant

Table of Contents

  • This field is for validation purposes and should be left unchanged.