Testing the Seal Integrity of Pouches and Eye Drop Bottles

January 11, 2018Cap Torque TestingBy Gabor Szakacs

It has been determined that release torque testing is not an appropriate way to test the seal integrity (tightness) of pouch caps or eye drop bottles. The problem with release torque testing is that these caps have integrated tamper evident bands and the tamper evident bridge break torque cannot be reliably and easily distinguished from the thread break torque of the cap.

Due to this design, there is a major concern with using the release torque as an indication of seal integrity. It can be difficult to differentiate between the thread break and the bridge break peaks. Also, it is possible to rotate the cap on the bottle neck to a point where the TEB is properly engaged but the threads are not tight, and the bottle is not sealed. If the TEB break torque of a loose cap falls in the acceptable removal torque range of a normal cap, it is impossible to differentiate between the release torque result of a tight cap and the TEB bridge break torque of a loose cap.

To overcome this issue, Mesa has implemented a new test method, one that tightens the closure and measures the rotation of the cap from the cycle start until the application setpoint is measured, instead of measuring removal. The more the cap is rotating, the looser the cap.

Using the Torqo 1600, you may use the “close measure mode” to replace the release torque test for seal integrity testing. The close measure mode is designed to measure the torque which is applied to a cap. The system will rotate the cap in the clockwise (closing) direction until the cap begins to rotate. The point at which the cap begins to rotate will be considered the application torque and will be displayed on the screen.

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About the author

Gabor Szakacs

Gabor Szakacs is the Product Manager for Mesa Laboratories' Torque product line. Since 2001, he worked for SureTorque Inc. and its successors in Sarasota, FL, then moved to Lakewood, CO after Mesa Labs acquired the automated torque testing products in 2013. Gabor received his M.Sc. degree in Electrical Engineering from the Budapest University of Technology and Economy. After graduating, he worked as a Business Information Systems Manager at New England Machinery, then he moved on to the industrial automation, packaging/package testing field. He has worked on various packaging machinery and automated package testing equipment designs, including those that measure pressure, force and torque. Today, he helps clients identify closure torque issues, customizes torque testing equipment and develops new test methods. Gabor is a member of the Packaging committee of the International Society of Beverage Technologists (ISBT) and the D10.32 subcommittee of The American Society of Testing and Materials (ASTM). He is passionate about educating packaging professionals about torque testing related issues and solutions.