O-ring joints

Photolysis Reactors and Ultraviolet Sources. For 253.7-m/ irradiation, a modified irradiation apparatus purchased from Delmar Co. was used. The reactor was a 2-necked, 500-ml., round-bottomed flask. One neck was an O-ring joint, and the other was a 24/40 joint. A 4- X 1-inch coiled low pressure mercury quartz lamp was placed inside the flask through the O-ring neck, and the joint was sealed with removable O-rings. The reactor was connected directly to the mass spectrometer by the 24/40 joint. The samples were placed inside the flask and irradiated internally. The O-ring was shielded from direct radiation so as not to induce degradation. The estimated output of the lamp was 30 watts, and the ambient temperature within the reactor during irradiation was 70°C. 

Fig. 1.14. Evacuablecell for UV-visible spectra. This cell is evacuated and then flushed through an inert-gas inlet attached to the O-ring joint. The Teflon stem of the valve is removed under flush, solutions are introduced through this Opening, and then tipped over into the cuvette after the valve stem has been replaced. Alternatively, condensable solvents and solutes may be condensed into the reservoir on a vacuum line.

Fig. 1.21. Typical assemblies of Schlenk ware. Commercial apparatus is illustrated similar apparatus with O-ring joints in place of standard taper joints is preferred by the authors. (

G. Variations in Schlenk Ware. A large number of modifications of the basic Schlenk ware are in use. The double-ended filter is a commonly used variant of the standard Schlenk filter. The particular unit illustrated in Fig. 1.29 is equipped with O-ring joints rather than standard taper joints. (See Chapter 8 for a discussion of joints and O-ring materials.) Either conventional or modified O-ring joints, such as the Fischer and Porter Co. Solv-Seals, have several advantages over standard taper joints for Schlenk apparatus these O-joints are more resistant to solvents than the conventional standard taper ware, the O-joints are more readily clamped together, and, unlike standard taper joints, the two halves... 

Fig. 4.3. Solvent storage tubes with Teflon valves, (a) The O-ring joint on the sidearm allows attachment to a vacuum line equipped with O-ring joints, (b) Same basic design as in (a) with a straight sidearm. This design is easily connected to a Schlenk line via Tygon or other flexible tubing that fits over the sidearm.

Metal ball joints, metal standard taper joints, and O-ring joints with a step tooled into Ihe groove are available from Kontes Glass Co., P.O. Box 729, Vineland, NJ 08360. The first two items are also available from Ace Glass Co., P.O. Box 688, Vineland, NJ 08360. 

B. O Ring Joints. The major difficulty with greased and waxed joints is their failure to hold vacuum when exposed to solvents, heat, and some chemicals. For many applications O-joints overcome these limitations. A successful glass Cl-ring joint which is in wide use is illustrated in Fig. 8.3, where it may be seen that both halves of the joint are identical. They mate with an O-ring fitted into a groove, and the two parts are held in place with a clamp. The two halves of these... 

Fig. 8.3. Cross-section of a Urry type glass O-ring joint and two types of screw clamps, (u) An O-ring. b) Cross section of a Urry-typc O-joint. Note the ridge which is tooled into the groove, (c) Two types of joint clamps. The upper one is manufactured by A. H. Thomas Co., Philadelphia, PA 19105.

Still another O-ring joint design is based on a glass fitting with an inner thread4 (Fig 8.6). 

Fig. 9.19. Solvent storage container. Solvent is distilled in through the sidearm, which is then sealed off under vacuum. The container is attached to the vacuum line through a 18/9 ball joint or O-ring joint.

Attention also is directed to other chapters which are useful adjuncts to the present one Inert Gases and Their Purification (Chapter 3), Purification of Solvents and Reagents (Chapter 4), and Joints, Stopcocks, and Valves (Chapter 8). The solvent and chemical resistance of elastomers, which are used in O-ring joints and septa, are discussed in Chapter 8 and Appendix III. 

Fig. 1.5. Joining two pieces of equipment under inert-gas flush. Both pieces are initially purged with inert gas separately before joining. Note the use of wire hooks and rubber bands to secure individual pieces of glassware. If the glassware is constructed using O-ring joints, the O-ring joint clamps hold the apparatus together.

External hydrogenation. The apparatus for this operation is shown in Fig. 2.63(b). It consists basically of three glass vessels, a hydrogen generator A, a hydrogenation flask B and a pressure control bubbler C, which are connected in series by means of air-tight O-ring joints. 

O-rings are commonly found on mechanical vacuum pumps, rotary valves, and O-ring joints. O-rings are used to separate environments. If an O-ring is attacked by the chemicals from one or both of these separated environments and fails, it will lose its protective sealing capabilities. Similarly, if an O-ring is left in a chemically destructive environment, it may become dysfunctional without ever having been used. 

The clamp size required for ball-and-socket joints is identified from the outer diameter measurement. Thus, a size 18 clamp is used for either an 18/7 or an 18/9 size O-ring joint. 

Because clamp identification numbers are derived from their relationship with ball-and-socket joints, there is no relationship between which size clamp should be used with which O-ring joint. There is no one-to-one relationship with O-ring joints and ball-and-socket joints one clamp size is likely to fit several different... 

The one-piece plastic clamp used with ball-and-socket joints will not work with O-ring joints. 

Table 3.3 O-ring and Clamp Sizes for O-ring Joints...

O-Ring Joint O-Ring Size Clamp Size... 

O-ring joints can easily be used with vacuum systems (<10 7 torr) and are particularly useful for quick-release connection. Occasionally it is necessary to leave a thin film of stopcock grease on an O-ring s surface to either help the vacuum capabilities of the joint, or to protect the O-ring s surface from the effects of a solvent. 

O-ring joints are measured by only one measurement the I.D. of the passageway through the joint in mm (the I.D. of the tube connected to the joint is sometimes a bit larger than the "A" measurement). 

The Tesla coil should not be used near O-ring joints because the coil can destroy the O-ring by burning a strip across its side. 

Demountable Joint Identification. Joints should be drawn and identified as being either an inner (male) or outer (female) section. Size should be identified as well (see Sec. A.2 and Sec. 3.1.1). Ball-and-socket joints should be equally identified (see Fig. A.2 and Sec. 3.1.2). Because O-ring joints do not have inner and outer sections, only their sizes are required (see Fig. A.2 and Sec. 3.1.3). 

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