schlenk line pt 2

A good working space is tantamount to good productivity. Schlenk lines are generally mounted on some sort of support, most typically a metal cage. (VWR lists these as "lattices" or "lab frames".) The cage serves not only as a support for the Schlenk line, but also as space to connect reaction vessels using clamps while they are being used. Most everything in the hood is held together with fasteners. The cage itself and other permanent fixtures are attached using smaller 90 degree frame connectors which are tightened down using small Allen wrench. Other items such as reaction vessels are attached on a temporary basis using thumb screws. When I first arrived at the Heller lab the hood assigned to me had a cage made of stainless steel and aluminum rods, fixed directly to the back of the hood. When I moved my work space the new hood was a mish-mash of rusty steel, corroded aluminum, and about half constructed with fiberglass rods. Totally unacceptable. This was totally disassembled and a new cage was constructed using only metal rods. No individual pictures exist of only the cage, but the reader should take note of the underlying structure in future pictures.

Building a Schlenk Line pt 1

A good Schlenk line starts with a good plan. In the figure I'm showing the basic sketch of the type of Schlenk lines used in the Heller Lab. This is scheme one of four and shows only the basic outline of the order we put in to the glassblower. There are five pages to the full schematic, one of written instructions and four of figures such as this one detailing the types of tubing, joints, lengths and thicknesses of glass etc. Either you are only a mildly interested reader and don't want to sift through pages of schematics or you are intimately interested and want to make a close copy. If you're the latter you should contact me, I might be willing to give it up (for a price). I will make a couple of suggestions as far as types of joints. The O-ring joints (the three joints in the bottom right of the figure which looks like bulges in the glass tubing) are all Urry-type O-ring joints. What are "Urry" joints, you ask? The glassblower who fabricated this glassware for us didn't know either. "Does that mean, 'eh, I need this in an 'urry'"? Well, no, it means that there is a raised edge running in the middle of the groove. When the clamp is tightened down the ridge presses against the O-ring which makes a better seal. This is particularly helpful when the joint is being removed frequently, as it ought to be if you are emptying the trap out every night. Dirt inevitably gets onto the O-ring and the Urry-joint will make a much better seal with a slightly dirty O-ring than a simple grooved joint will. As it turns out, there's not many glass manufacturers who make a simple groove anymore, but if you happen to get a hold of one save yourself some time and toil; drop it on the floor right now.

There's a design flaw in the sketch above. Its not terrible, but embarassing that it made it all the way through to the final product without getting caught. I'll mention it next time.