Heli-Grid

Purification. a-Methylstyrene was purified by distillation through a 6-foot, Heli-grid-packed, modified Podbielniak column under a reduced pressure of dry helium. Purity of the distillate was established by vapor phase chromatographic analysis, using flame ionization detection and an appropriate column. Sample purity generally ranged from 99.90 to 99.98%. 

A typical gas-distillation column is shown in Fig. 3-16. The column itself is a small-diameter tube, usually on the order of 6 mm inside diameter, which contains the packing. The Heli-Grid type of pack-... 

Podbielniak columns with stainless-steel Heli-grid packing may also be used. 

How strongly warm flooding influences the efficiency is clearly seen in Fig. 101. The tests were done in a Podbielniak column of 25 mm diameter with Heli-grid packing (Fig. 275) at a load of 1000 ml/h. It is seen that the stationary state was reached only after 8 to 10 hours and that the flooding increased the plate number up to 50% [213]. 

The basic work on the analytical distillation of gases (comprising the permanent gases, the gaseous and lower liquid hydrocarbons) was carried out by Podbielniak [94], who for this purpose developed an effective column containing a closely-woxmd wire spiral known as Heli-grid packing (see chap. 7.3.4), which has also proved its worth for normal distillations. 

On account of their extremely low HETP s, even at high loads, Heli-grid coliuuu. < are of value for analytical distillations. Together with the concentric-tube and iiiul-tiple-tnbe columns they constitute the most efficient group of columns at present known. 

Data for columns with heli-grid packing... 

Pack the column carefully with any suitable material. Some common packings in order of decreasing efficient are Heli-Grids, Heli-Pak, glass helices, and glass beads. 

Wire Produced as Heli-Grid and Heli-Pak packings... 

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