The purpose of the stillhead is to divide the vapour emerging from the top of the column into two streams. This it does by first condensing the vapour to liquid in a heat-exchanger and then, as the liquid runs back down through the column to the boiler, diverting a portion of it to the outside world via a small valve. This valve has only a small volume of liquid to handle so, for fine control, choose a needle valve.
Two different designs for a stillhead made out of copper are shown. The first, an offset design which was shown in Figure 3 and which for obvious reasons we whimsically refer to as the "Mexican cactus", has the still-head shown in more detail in Figure 5. The second, again because of its shape, we refer to as the "Hatstand", and is shown in Figure 6. They both work very well — it's simply a matter of appearance and ease of construction — so the choice is up to you.
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