[quote=nuclearnerd;1616457]I've heard a lot of these rules of thumb for getting push to connect fittings to hold reliably. We've worked at trying to cut tubing square, pushing the tube all the way into fittings, and throwing out any batch of tube we thought was failing repeatedly. There's probably more we can do for quality assurance, but at some point I have to step back and think "there has to be a better way".
In 2015, we used all plastic push connect fittings similar to the ones that are seen in your photo and also had issues with them failing. We switched to ones with a metal ring (like the ones here
http://www.andymark.com/product-p/am-2015.htm) and also started using pneumatic tubing cutters to cut our tubes square. The new fittings work much better.
*sorry I don't know how to use this forum very well*