A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

THE DISTILLING CONDENSER. 147 (6) The Casing. 27. The casing enveloping the tube surfaces is best made of sheet copper. If weight and space are not objected to, the casing can be made of cast iron or steel plate, in the former the corrosion is less. It is usual to galvanise the casings if iron or steel. This acts as a preservative, and when iron or steel is used it is customary to fix zinc blocks at suitable parts of the casing, to divert the galvanic action from the casing. These zinc blocks should, however (as said in a former part of this book with regard to evaporator casings), be carefully fitted—i.e., clean metal to metal—or the danger sought to be obviated may be aggravated. 28. The cover of the distiller may consist of a single piece of thin sheet copper, gripped between the flange of the casing and an iron ring, as shown at H in Fig. 17 (p. 136). This arrangement has the advantage of superseding an expansion joint for the tube sheaves. 29. Fhe distiller casing, usually cylindrical, is generally subjected to a test pressure of 40 to 50 lbs. per square inch. It is usual to make the shell in halves or sections for convenience of taking apart in confined places—that is, if the casing has considerable height. (c) Fittings for the Distiller. 30. The usual fittings are as follows (1) A steam valve (if required for the mode of working). This is required (1st) if the distiller receives pressure steam from the evaporator, or (2nd) if the distiller is made to work at a minus pressure, i.e., less than the atmosphere under normal conditions, inside the tubes. If the distiller is intended for working in 1st way only__