On the face of it, easy. But on closer inspection, challenging.


That’s oil drum internal inspection

When a customer asked us to provide a camera that would allow them to inspect the insides of new oil drums at the end of the production line, we made the assumption that any reasonably small camera would be good enough for the task.

However, the standard oil drum has a 2″ aperture at the top through which any camera assembly would need to fit. There are many small cameras on the market that would fit through a 2″ aperture. But taking into account the operational requirements that meant attaching the camera to an existing probe that also has to fit through the same space, meant that the majority of small industrial cameras are too big.

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In addition, the specification was made more challenging because:

  • Every centimetre of the internals of the drum had to be inspected, requiring more than one camera
  • The cameras had to enter the drum and exit within 30 seconds
  • The live images needed to be displayed on a large screen
  • High resolution images were required so that the smallest objects could be detected
  • Allowing for routing around and through a moving production line, the cable distance was around 15 metres
  • The whole process had to be semi-automated so that the operators only have to watch the screen

There is one camera in our portfolio which stood out as the best candidate. Cable run had to be minimal and so power over ethernet was an obvious choice, meaning the miniature power over ethernet cameras from The Imaging Source were an ideal choice.

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The cameras mounted at 180 degrees, with LED strip lights and M12 miniature lenses

Then the next problem became apparent, standard lenses are bigger than the width of the body of the camera, so we had to go to small lenses. Fortunately there is an M12 lens adapter available from The Imaging Source that converts the C mount to an M12 mount. Now we just had to find fish eye lenses with a wide enough angle to view each end of the drum.

Finally, how to illuminate. Standard lighting couldn’t be used as there was nowhere to put it. We came up with the idea of using LED strips which work off 12V DC. These attach to the side of the camera and as they are low power they don’t get very warm.

Once we’d cracked the camera and lighting problem, we then had to display the live images on the big screen. For this we used Scorpion Image Sentinel, designed for uncompressed image capture at live video speeds.

What the inside of an oil drum looks like!

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