For pipeline x-ray equipment containing liquids, slurries and pastes, test samples should ideally be placed independently in the product flow. The reject device should then be observed to successfully reject the test sample. The test sample should be encapsulated in a colored material that is different to the product, making it easily identifiable in the rejected product. To verify that the reject timing is correct, the test piece should be located in the center of the rejected product. The test should be repeated, typically three times.