It is true that the more squeeze you place on an o ring, the tighter the seal it will provide. In essence, the more squeeze (compression) you apply, the greater the force between the o ring and its mating hardware.
And ensuring you have the perfect seal is all reliant on the squeeze force applied, as a tight seal is what helps liquids and gases from escaping from the application.
At specialistsealingproduct.co.uk, we stock a range of different gaskets, seals, and o rings to suit various applications in various industries.
However, when it comes to squeezing and how much force you should apply, this is of course dependent on the mating surfaces and o ring material itself. In this post, we look at squeeze force further, factors affecting squeeze percentage, and why more squeeze is not always better.
Squeezing force applied to o rings
Finding the optimum level of a squeeze for your o ring and application will come down to a series of tests and, in some instances, trial and error.
Yes, the more squeeze that you apply, often the better and stronger the seal will become, and the longer it can maintain the force applied. In these instances, the ability of an elastomer to maintain its compression set is vital as, ultimately, it dictates the ability of the elastomer to maintain its push back.
If we examine this a little further. If the elastomer has an o ring compression set of over 80%, it is unlikely that it will return to its original uncompressed state when it is not squeezed. Hence causing damage and allowing leaks to appear.
Other influencing factors affecting o ring squeeze include:
Damage upon installation – the installation of an o ring can be a delicate process. In some cases, during the installation process, the tighter the squeezing force you apply, the more likely you are to pinch the o ring, creating an opening for leaks.
O ring material – o ring material choice is vital because specific elastomers and compounds will only stretch so far before they crack or rupture because they have been squeezed past their optimum percentage levels. It’s also important to note that rubber seals do not compress volumetrically, so you must avoid over-compression if this is your o ring material of choice.
Gland volume to o ring volume must be measured – this area focuses on not overpacking the gland. During the installation process, you need to make sure that there is enough groove volume to accept the o ring. Allowing the o ring to fit into the groove and expand as required. Too much o ring volume and not enough groove volume will overpack the gland causing damage and seal failure. Ideally, the o ring must fit snugly into the gland, and the o ring volume should never exceed 90% of the minimum gland void as this will cause premature failure of the seal.
Achieving the perfect o ring compression and function is vital. In some cases, engineers work on testing the leak path ratio between the o ring and its mating surfaces to avoid potentially premature failure.
Sometimes it does not matter how much squeeze you apply to o ring seals. Factors such as gas permeation, the seal’s interaction with certain chemicals, mechanical damage, thermal degradation, etc., will all cause the o ring seal to perform poorly, no matter what.
This is why testing optimum squeeze levels and choosing the right materials and compounds can be vital. Every application is different; hence every o ring compression set will be different.
Finding out the right percentage level for your seal and mating surfaces before mass-scale production takes place, is, therefore, essential.
There are numerous factors when considering the squeezing force of an o ring. Specialist o ring suppliers in the UK, like the team at Specialist Sealing Products, will be able to provide you with further sealant advice and information, as well as refer you to manufacturing instructions if applicable.
If you are looking for the perfect o ring seal, look no further than SSP for all your gasket and sealing requirements.
Reference video: tarkka