How to Use Open-Top Tubes in Ultracentrifuges

Open-top tubes from Beckman Coulter Life Sciences are a simple option for ultracentrifugation that come in a variety of materials to meet your application needs. Thin wall open-top tubes, which come in polypropylene or ultra clear, should be filled roughly three fourths full or up to two to three millimeters from the top of the tube for proper tube support. Polycarbonate and stainless steel tubes may also use caps. Regardless of the tube format enclosure, be sure to inspect tube and cap components for cracks, nicks, or flattened regions prior to use. Also, be sure they are dry and free of lubricant during assembly. Tube cap assemblies include a stem which comes from a nylon insert already inside, an o-ring or flat gasket, a crown, a hex shaped nut, and a stainless steel set screw. Not all tubes require every piece of the assembly. Be sure to reference the IFU for individual needs. To cap a tube, first loosely assemble the stem, the o-ring, the crown, the crown washer, if using, and the nut. Slide the tube up around the stem past the o ring, slightly rotating the cap assembly. Tighten the nut just enough to hold the cap in place. The tube wall should pass between the o-ring or gasket and the crown so that the top of the tube rests on the underside of the crown. Now, position cap tube into the tube cap vise. Tighten the tube according to the instructions for your tube. Some tubes require a torque wrench, do not over tighten. Use a syringe to completely fill the tube through the hole in the cap. With the tube removal tool, tighten the pointed set screw firmly on the nylon insert in the filling hole, sealing the tube. Your sealed tube is now ready to run-in the centrifuge. Please refer to the appropriate tube and rotor instructions for use or IFUs for more detailed information regarding tube capping, filling, and sealing.