I have had a dodgy set of line that caused leaks (i.e. not quite 8mm OD), but the same fittings with another batch of line was fine
Is this the first time you've used any push fittings? Just wondering whether you know about them having to go in straight without bends right at the join..
Yes this is absolutely something we have noticed with some competitors beer line. We would recommend EVABarrier as it's great value and made to a high specification and tight tolerance especially the OD of the line. Clearly this is one of our own brands. If you want to use a competitors beer line I would also recommend the Valpar as also has tight tolerances on the sizes so this works just as well but it's generally not as good value as the EVABarrier that we have.