Regular testing is required to ensure that the contaminant detectors are operating within the specified sensitivity standards. Testing must verify that contaminants are reliably detected and that, in the event of product contamination, the appropriate separation mechanisms and signal/alarm devices are activated.

Perform testing

Verification tests must always be performed with the highest demands on the detector (worst case). This includes:

- Using the most common or difficult to identify contaminants

- Placing the contaminant in the most difficult to identify location within the product

- Placing the contaminated product in the location of the detector with the lowest sensitivity (usually in the centre of the detector)

- Testing the separation mechanism/signaling device with a number of contaminated products in succession

Using test bodies

As a rule, ferrous (FE), non-ferrous (NFE) and stainless steel, non-magnetic (V2A) test materials are used to perform contaminant detector verification tests. The test bodies are ball-shaped and therefore allow testing independent of location and shape.

For example, testing a variety of different types of objects with balls.

- MiniStick test 10 x 10 x 20 mm made of glass

- Stick test 10 x 10 x 100 mm made of glass

- Block test 20 x 20 x 20 mm made of glass

- FlexStick test l = 250 mm

- Ball test Ø 25 mm made of POM

In principle, verification tests can be performed with only test objects, i.e. without the product. However, for reliable test results, it is always necessary to perform a detector test with the product. For this purpose, a test object is installed in the product or attached to the product in a position that is most difficult for the detector to determine.

In the case of packaging testing (the test object in or on the product being tested), this must be determined before the test is carried out.

- How to ensure that the product used is not contaminated before the test part is attached

- Where on the product the test object should be attached,

- After a period of time new test packs should be used (old products cause inaccurate detection),

- How to ensure that the test pack will not leak into the supply chain (e.g. by colour marking).

Test frequency

In general, verification tests should be carried out at the following times:

- When changing shifts, at the start and end of daily production

- When a product change has been made

- When a batch change has been made

- When a machine setting has been changed

- After a production stoppage, for example due to repair work

- Periodically during production

In the verification process, three test runs for each test object and location are considered necessary. In cases where detector performance is good, one test per object and test location is considered best practice.