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

 MULTIPLE DISTILLATION. several feeds automatically regulated, and the brine densities in the boiler and each evaporator thus kept uniform. 97. It is important that the pump, whilst drawing away the various feed-waters from these various compartments, should avoid drawing air, for any air drawn through the feed pump would find its way into the boiler, or the coils of the evaporators, and cause the apparatus to work less easily than if nothing but water were fed in. This may- be guarded against by having floats in each of these com- partments, so fitted as to close the pump suctions by their sinking action when the water gets below the level of the suction pipe end. (/) THE PUMP. Its Functions. 98. The pump usually supplied with the apparatus has three distinct functions :— First.—It circulates the sea water through the dis- tilling condenser. Secondly.—It supplies the feed-water to the various parts of the apparatus that generate steam—that is to say, to the boiler and each evaporator, all of which have separate pumps, but the whole is combined in one machine, as a rule. Thirdly.—It pumps away the fresh water that is produced. 1. Circulation Pump. 99. As to the circulation pump, what lias been said at p. 153, when dealing with the distilling condenser as to the quantity of circulation water required must be con- sidered in calculating the size of this pump to meet those