In-line leak tester from Sepha
revolution in the blister packaging sector by unveiling the first
clean, non-destructive alternative to the methylene blue dye test
(MDT) for leak testing. Now, the company is gearing up to deliver a
new first - a vacuum-based tester that could check blisters as they
come off the production line.
The company's founder and president, Ernest Parker, told In-Pharmatechnologist.com at the TOTAL 2004 exhibition that the new system is in development and could be on the market next year. The current prototype can handle around 300 blister packs per minute, but this will probably be increased to 1,000 packs a minute in the production model, he added.
Many companies still rely on MDT to test blister packs are sealed properly and have no leaks, even though the procedure is messy, prone to error, destroys the packs tested and cannot be validated as part of an audit trail. The test involves placing the packs in the dye, raising the pressure and checking visually if any dye penetrates into the blisters.
This method can probably only be relied on to detect holes or pores of around 30 microns in diameter, but Sepha's alternative system, which uses a combination of a vacuum and a laser sensor detect leaks, is more sensitive. In essence, the technology involves placing the blister in a low pressure environment which will make the foil under the blister bubble out.
The height of the bubbling is scanned along the mid-line with the laser and if it still lies flat there is clearly a leak. With calibration, the machine can be set up to detect holes of any size down to around 5 microns in diameter, although users can specify the threshold for rejection. It takes about two minutes to detect leaks across the full blister web using the current machine, called the BlisterScan.
Moreover, Sepha's technology can identify the precise pocket that is leaking on a blister pack, which pinpoints the location of any quality inconsistencies in the packaging material or the sealing process. For example, it could detect a defect in a packaging machine - or even a developing problem that is not yet causing rejections - allowing operators to stop the line and investigate immediately.
The result should be increased line efficiency and less wastage and, as the process is non-destructive, the contents of failed packs can be recovered and re-blistered.
