Our lab's Schlenk lines are currently equipped with the rather standard oil-filled bubbler as back-pressure regulators. They work mostly OK, but come with the usual set of drawbacks, such as the very low over-pressure and the occasional instance of the oil being sucked into the line. Since going back to the good-ol' Hg bubbler is not a realistic option, I was wondering if anyone can suggest a good lab-tested mechanical (spring loaded?) option for back pressure control alternative. We're in Europe, so I am especially interested in anything that is already commercially available here. However, any good design is highly welcome.