Part 4: Testing of Contaminant Detector Performance According to BRC Standards


Regular tests (verification tests) are required to ensure that employed contaminant detectors operate within specified sensitivity standards. The test must verify that contaminants are reliably detected and that in case of a contaminated product corresponding separation mechanisms and signal / warning devices are activated.


Performing the test

Verification tests should always be performed with highest demands for the detector (worst-case scenario). This includes:

  • Using contaminant types that are expected or that are the most difficult to identify
  • Placing the contaminant at a position inside the product where it is most difficult to identify it
  • Placing the contaminated product at the position of the detector where sensitivity is lowest (as a rule at the centre of the detector)
  • Testing the separation mechanism / signal device with several contaminated products directly following each other

Using test bodies

As a rule ferrous (FE), non-ferrous (NFE), and non-magnetic stainless steel (V2A) test bodies are used for performing verification tests of contaminant detectors. The test bodies are ball-shaped and thus allow testing independent of position and shape.
Sesotec provides various types of test bodies with moulded-in test balls:

  • Test MiniStick 10 x 10 x 20 mm made of plexiglass  
  • Test Stick 10 x 10 x 100 mm made of plexiglass
  • Test Cube 20 x 20 x 20 mm made of plexiglass
  • Test FlexStick l = 250 mm
  • Test ball Ø 25 mm madeo of POM


Basically verification tests can be performed with test bodies alone, i.e. without the product.  However, for reliable test results the detector test always should be performed with the product. For this purpose a test body is inserted in the product or attached to the product at a position where it is most difficult to identify for the detector.

If the test is performed with test packages (test body in or at the inspected product),  it must be determined before the test

  • how to ensure that the employed product is free of contaminations before the test body is attached,
  • at which position of the product the test body must be attached,
  • after which period of time new test packages should be used (product ageing causes incorrect detections),
  • how to ensure that the test package will not get into the supply chain (e.g. by way of colour marking).

Frequency of tests

Basically verification tests should be performed at the following times:

  • At shift change, and at the beginning and end of daily production
  • When a product change has been performed
  • When a batch change has been performed
  • When machine settings have been changed
  • After a production standstill, e.g. due to repair work
  • At regular intervals during production

In a verification process three test runs per test body and position are considered necessary. In case of good detector performance one test per test body and position is to be considered best practice.



Here you can find all parts of our guidelines on contaminant detection in the food industry

Part 1: Basics of Metal Detection in the Food Industry
Part 2: Use of X-ray Inspection Systems in the Food Industry
Part 3: Determining Critical Control Points in Food Production Processes
Part 4: Testing of Contaminant Detector Performance According to BRC Standards