The boiler may be made of cast iron but the baffles and the condenser tubes that come into contact with the product are made of stainless steel or monel metal.
The cold water from the water tap enters the still through the inlet, which rises in the jacket fitted with a constant level device, the excess of water overflowing through the outlet.
A portion of hot water at 90 to 950C enters into the boiler through a narrow opening – the level of water is maintained in the boiler up to the overflow level.
The water is boiled in the boiler by means of heating coils. On heating, the dissolved gases in the condenser are allowed to escape through a small opening and only the steam escapes into the condensing tubes.
Since the dissolved gases are more volatile than water they escape in the first portion of the distillate, therefore, must be rejected. Similarly, the last portion may contain volatile portions of the dissolved solid substances in tap water – hence, discarded.
Commonly Asked Questions.
With help of a well labelled diagram describe the construction and working of the apparatus used for preparing purified water.