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Pinhole Detector, Principle and Working in Pharmaceutical

“Pinhole Detector” is used in pharmaceuticals to detect a hole in lidding foil/aluminum foil. Sometimes, it is not possible to detect the small hole with the naked eyes that is present in foil. So, to detect these types of holes, a pinhole unit is installed between the forming station and the feeding channel of a machine.

pin hole detector
Pinhole detector Device

The function of the Pinhole detector:

The primary function of the pinhole detector is to detect the presence of holes in aluminum foil.

Principle of Pin Hole Detector:

The pinhole detector is a multi-voltage device that uses the wet sponge principle to detect pinholes, cracks, and damaged areas in non-conductive coatings on conductive substrates. Wetting agents penetrate any pinholes and create a conductive path through the substrate. wet sponge test is a testing technique used to identify any gaps or inconsistencies in the coating film.

During the challenge test, the light source emitted light through-hole/damaged foil, and that light fell on the light detection device that is placed below the foil.


To perform the challenge test, follow the procedure as per SOP. make a hole in the foil with the help of the given needle and fix the reference standard of 25 microns (0.001 inches) over the hole. The hole should be seen through reference standards.

After affixing the reference standard to the foil, start the machine to pass the hole and start reference through the pinhole detector.

During this hole is sensed by the Detector, and at the same time, the red light of the Detector will blink, and product feeding should be stopped, and the system should reject the same blister.

Perform the test at different positions on the foil, and the same shall be recorded in the Batch packing records.

Related PostSOP for Camera vision system and pinhole detector

Frequency of challenge test:

Challenge test shall be performed at the start of batch or as given in the SOP.

  • Naresh Bhakar

    Naresh Bhakar is the Founder and Author at Pharmaguddu.com, bringing his extensive expertise in the field of pharmaceuticals to readers worldwide. He has exprience in Pharma manufactring and worked with top Pharmaceuticals. He has rich knowledge and provides valuable insights and data through his articles and content on Pharmaguddu.com. For further inquiries or collaborations, please don't hesitate to reach out via email at [email protected].

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