Ultra-Torr fittings

Fig. 3.13 The Cajon Ultra-Torr fitting.This illustration of a Cajon Ultra-Torr Fitting is used with permission of Swagelok Co., Solon, Ohio 44139. The illustration was supplied by the Swagelok Co.

Gas-handling system for gas dielectric constant determination. Many connections are made with Swagelok and/or Ultra-Torr fittings. The gas lecture bottles must be securely fastened to the laboratory bench. 

Since the data-acquisition time for a given S/N scales inversely with the square of the number of molecules sampled, high pressures and large tube volumes are desirable. NMR tubes are produced in a range of diameters, and the largest of these that is compatible with the instrument probe design should be chosen. Tubes of 5-, 10-, and 15-mm diameter with an in-line Teflon valve, which permits easy attachment to a vacuum line via i-in. or -in. Ultra-Torr fittings and which can be spun in the normal way, are available from various suppliers. 

FT-NMR spectrometer, with 10- or 15-mm-diameter probe capability if possible gas NMR tube with concentric Teflon valve (e.g., J. Young NMR-10) 1-L reaction flask with greaseless stopcock 0- to 1-bar pressure gauge vacuum line Ultra-Torr fittings microsyringes hot plate and oil bath with 0 to 200°C thermometer liquid N2 and ice baths benzoyl chloride and bromide, D2O (95 percent) fume hood. 

Ultra-Torr fittings (Fig. 4) seal by means of an 0-ring, usually made ofViton, and are especially useful in making glass- metal- plastic seals in simple vacuum systems. Viton is a rubberlike material with a very low vapor pressure, and Viton 0-rings can be baked to 200°C. Teflon is also occasionally used as a material for 0-rings. 

---