Special Tubes

Stability is a major issue in radiometric applications and asks for a special tube design and processing as well. 

Special Tubes A variety of special forms of the pitot tube have been evolved. Folsom (loc. cit.) gives a description of many of these special types together with a comprehensive bibhography. Included... 

Special tubes are available that can be used for long-term average concentration, rather than instantaneous. 

When it is necessary to control the temperature of the liquid, the tube is opened at one end immediately after the reading and a thermometer inserted. Better still, in cases where variations of temperature exert a marked influence on the result, special tubes may be used which are furnished with a T-branch containing a stopper traversed by a thermometer and are surrounded by a metallic jacket through which water at constant temperature is circulated. 

Features Special tube for Versatile, tough Waterproof, ... 

An ordinary distillation flask with a long neck is used as a receiver. If various fractions are to be collected, the distillation is interrupted after each fraction, and the receiver is changed. This operation takes only a short time. The manometer is not put in the line with the pump, but is attached through a special tube so that no liquid can get into it. It is important to have a safety cock in the system so that a small amount of air can be admitted, and the distillation immediately brought under control if the liquid in the distilling flask begins to boil over. The... 

Tygon (Either metal, Nylon, or polyethylene fittings can be used, but a special tube... 

Figure 5.3 Welding Torch Hydrogen gas is piped into a special tube in which many of the H2 molecules are separated into atoms by an electrical discharge. The gas flow is adjusted to the rate at which most of the H atoms recombine into molecules just as they exit from the torch. The heat produced at that point is intense enough to weld pieces of steel together.

The simplest system for evaporation by gas blow-down is shown in Fig. 17.3. A Pasteur pipette is connected by a flexible tube to a cylinder of nitrogen, which has a gas blow-off safety system (p. 125). The sample is placed in a special tube with a conical base, such as a ReactiVial . Hold the Pasteur pipette and direct a gentle stream of nitrogen towards the side of the tube so that it flows over the surface of the liquid. As the solvent evaporates, the liquid and tube will cool and may condense atmospheric water into the tube. To prevent condensation, clamp the tube in a warm sand bath or above a closed steam bath or in the hole of a purpose-designed aluminium heating... 

Many commercially viable methods of inducing swirl flow inside of tubes are available in the form of either swirl flow tube inserts (twisted tapes, helical cores, spiral wire inserts) or special tube configurations... 

Evacuated blood tubes may be made of soda-lime or borosflicate glass or plastic (polyethylene terephthalate). Because of the decreased likelihood of breakage and hence exposure to infectious materials, many laboratories have converted from glass tubes to plastic tubes. Tubes made from the soda-lime glass may release trace elements, particularly calcium and magnesium, into solutions. Special tubes are available for trace element determination (Table 2-2). 

The apparatus of Hempel is filled with glass beads which act like the sieves in the Linnemann apparatus. For -the distillation of large quantities of a liquid the Hempel apparatus is-particularly well adapted in working with it as well as the Linnemann form, the heating must be interrupted from time to time, in order that the liquid collecting in the beads or sieves may have an opportunity to flow hack to the distillation flask. If the Le Bel-Henninger form is used, this precaution is unnecessary, since in this apparatus special tubes for conducting off the condensed liquid are joined to the sides of the bulb somewhat above the sieves-... 

Part 23 of ISO 787 contains a description of an alternative method which allows to remove air entrained in the sample of a powdered material. The powder is placed in a special tube, mixed with an excess of the displacement liquid more than sufficient to cover its surface, and placed in centrifuge to remove air. 

Parts with an open coherent porosity of >20% are used in vacuum tubes and aeronautics because of refractoriness, shape stability, and chemical resistance. Examples are porous cathodes impregnated with alkaline earth oxides as electron-emitting sources in special tubes, thermoionic converters heated by nuclear energy, and ionic propulsion units with porous tungsten plates as ionic sources for Cs vapor of high temperature. Those emitter plates are made of globular tungsten powder (7 pm) density 75-85%, pore size 2-30 pm, and pore number 1.4 x 10 -8 x 10 cm . ... 

To facilitate and speed up ELISA procedures, besides the PollRhne press, 8-channel plpets and special tube racks mentioned already (Figure 3), other equipment is used or under development ... 

Rather than have to buy several rotors, it is more economical to buy a large size rotor and then to buy adapters for use with either smaller tubes or speciality tubes. Figure 39-17, p. 465, shows several types of adapters. 

Figure 39-19. Special Tubes For Fat. Left to right skim milk, milk, ice cream, cream, and cheese.

Katz et al. [127] and Nakajima and Shiozawa [128], for example, found that coefficients on the upper finned tubes in a bundle are higher than coefficients on the lower tubes as a result of bubble-enhanced circulation. Similar results are reported by Arai et al. [129] for a bundle of Thermoexcel-E tubes. It is quite probable that with certain types of enhanced tubes it is sufficient to use the special tubes only in the lower rows since the bubble-enhanced circulation in the upper rows is so high that enhanced tubes are not effective there. 

---