The glass still

The glass still shown in Figure 7 and described in the following paragraphs is essentially the same as the hatstand model discussed above, but there are one or two innovations which make it particularly pleasing. All dimensions are given so you can take it along to a glassblower and he will know exactly how to make it for you.

The column and stillhead are made from 38 mm O.D. glass tubing, joined by means of a 34/45 drip-tip standard taper joint. A teflon sleeve is placed between the male and female halves of this joint in order to avoid "freezing". Normally the joint could be greased but hot alcohol would soon flush this out leaving a dry glass-to-glass joint which would "freeze" and be very difficult to separate if you ever needed to. Hence the teflon sleeve which the glassblower will supply.

The cooling coil is made of copper rather than glass because a glass coil would have insufficient cooling capacity to condense the alcohol vapours effectively. As with the copper hatstand model, all the condensed vapour, from both

the cooling coil and the interior walls of the stillhead, falls into the collection cup, the drip-tip being located inside it. This collection cup has two outlets, i) a tube at the bottom-side leading to the draw-off valve on the outside of the column, and ii) a central tube which acts as overflow when the draw-off

To use, turn stopcock to OFF position for total reflux. Then turn 90 deg. for pre-set 10:1 reflux ratio.

To use, turn stopcock to OFF position for total reflux. Then turn 90 deg. for pre-set 10:1 reflux ratio.

FIGURE 7a. FINE CONTROL

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FIGURE 7a. FINE CONTROL

valve is closed sufficiently.

The draw-off valve, therefore, has the ability to change from zero to 100% the ratio of condensate drawn off to the outside world to that which is returned back down through the column to the boiler.

Normal teflon stopcocks are not easy to adjust for fine control of liquid flow, so a fine control has been added and is shown in Figure 7a. To make this modification a hole is drilled and tapped from one end of the teflon plug and a small brass bolt introduced which can close completely the hole supplied by the manufacturer. With a fine thread on this bolt and a knurled knob to turn it, very precise control is possible. A particularly nice feature of this design is that the teflon stopcock can be turned to the closed position for total reflux while equilibrating the column, and then turned 90° to the open position where the pre-set fine control will immediately provide the 10:1 reflux ratio for product withdrawal. Note. This will become understandable after you have read the operating procedures and the principles of fractional distillation a bit later on.

The thermometer is introduced on the opposite side of the column to the draw-off valve, and slightly offset so that it avoids the down-comer from the collection cup. If temperature is to be measured with a digital thermometer then a small teflon plug can be inserted in the 10/30 joint.

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Making Your Own Wine

Making Your Own Wine

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