Plug seal arrangement

When very high insulation is required (R 10 fi), the electrical lead-through can be mounted on a pierced sapphire plug using a double Poulter-seal arrangement (cf. Chapter 3, section 5), as shown in Fig. 3.4. 

Ceramic crucibles are frequently enclosed in slightly larger iron crucibles, which are then hermetically sealed with a welded-on plug this arrangement combines the chemical resistance of ceramics, especially the oxides of Be, Mg, Al, Zr and Th, with the ease of sealing of iron crucibles. 

A tube of difficultly fusible glass, sealed at one end, is filled with a mixture of 3 parts of dry sea-sand and 2 parts of ammonium nitrate dried at 105°, which is kept in position by an asbestos plug the end of the tube is closed by a cork through which passes a delivery tube with a tap. A small aluminium box, fitted with a thermometer and serving as an air-bath, is arranged to slide along the tube. The best temp, to employ is 260<,-285°, and the back end of the tube is first heated when all the air has been expelled from the tube, the gas is passed, first through aqueous ferrous sulphate or alkaline sodium sulphide soln., VOL. VIII. 2 c... 

Unlike the emergency rods, the central rod may be at any position in the pile. It has to be cooled, which is most simply done by water circulation, and by dissolving boron in the water it can be arranged to have most of the heat produced directly in the solution itself without having to get it transferred there from the tube walls. This leads us to the type of control rod pictured in Fig. 16. The plug at the top gives a radiation seal when the rod is entirely... 

The anode assembly contains 16 anodes arranged in two parallel rows of eight each. Two assemblies totalling 32 anodes are used in each cell. A recessed bolt sealed with a carbon plug fastens the anodes to a copper support bar. This design... 

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