FEATURE u Test & Measurement


Comparison of leak testing methods: When it has to be tight


How can manufacturers test the leak-tightness of their products? Geert Elie from WITT, supplier of leak testing equipment, gives an overview of the possibilities and explains the pros and cons.


F


or customers who want to test their products for leaks, I recommend an entry- level solution to test in a water bath. This


is a very simple, yet effective method. The test specimen is held under water and the tester watches for rising air bubbles. It is very intuitive. In principle, it’s like patching a bicycle tube, except that the product is not inflated, but tested in a vacuum chamber. The product inflates itself, and bubbles escape from leaks. The important thing is: You not only know that the packaging is leaking, but you also immediately recognise where. This allows weak points in the process to be detected and eliminated. It is not without reason that our LEAK-MASTER EASY is used by so many customers.


AND WHICH PRODUCTS CAN BE TESTED IN THIS WAY? Practically everything that has to be leak-proof. Often it is packaging, e.g. tubular bags, stand-up pouches or thermoformed trays, even vacuum packaging can be tested with the EASY. Mostly it is about meat or sausage products, salad, bread, snacks, dairy products, pet food or medical products. Even the popular coffee capsules are possible. And lights, bubble wrap or plastic parts must also be leak-tight.


WHEN SHOULD A USER OPT FOR A WATER BATH AND WHEN FOR A CO2 UNIT? Water bath devices provide the cheapest method; they’ve been proven over may years and work reliably. If I want to find out where my product is leaking, I need a water bath in any case. And if I don’t have CO2 in the product, or I have a vacuum pack, the water bath is the best option. For more standardisation and automation, CO2


units are a good choice. This is because they do not need to be inspected by a human inspector. The result is still absolutely reliable even after the umpteenth test at the end of a long working day. Second point: You can test the leak-tightness without destroying the product. And finally, testing without water is cleaner and less complicated. Regular changing of water and cleaning are not necessary.


20 November 2021 Irish Manufacturing Ideally, I have both devices. With the CO2


device, I perform all spot checks safely and non- destructively. In the case of a leaking package, I can use the water bath to find the position of the leak and eliminate the weak spot. But when it’s random sampling, a leaking


product could still reach the customer, with its consequent loss of quality. How can this be reliably prevented? Only a 100 per cent inspection offers 100 per


cent certainty. So I usually need an inline solution. Here, too, machines with CO2 sensors have become well established in practice. Like our LEAK-MASTER MAPMAX, for example, which food producers all over the world use to ensure perfect packaging and thus the quality of their products.


As with the PRO 2, the MAPMAX receives all the packages from the packaging machine. A vacuum is created in a chamber. Sensors detect escaping CO2. And what happens if a leak is found? There is an alarm directly on the device. In addition, leaking packages can be physically rejected. Everything is fully automatic. What’s more, it’s very fast and absolutely reliable. The MAPMAX manages up to 15 cycles per minute. In most cases, the MAPMAX is used to directly test whole batches or cartons. There are indeed some faster machines on the market where pressure is applied to the package via a roller. However, this method is quite coarse and only finds very large leaks. This is not fine enough for most products. In fact, testing outer packaging is the safest because the testing is done at the very end of the process. After that, the packaging is no longer touched and cannot be damaged.


SO INLINE TESTING IS THE SILVER BULLET OF LEAK TESTING? Whether random testing or inline is actually needed depends greatly on the product, the packaging, the process, the Best Before Date, and also the distribution channels. But in any case, inline offers the maximum certainty.


WITT www.wittgas.com www.irish-manufacturing.com


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