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

THE EVAPORATOR. 131 keep the pressure of the secondary steam at about | lb. per square inch (equal approximately to 6 inches head of water). When the pressure inside the casing is at | lb. per square inch, the brine in the casing will be forced up pipe (P) until it reaches about 6 inches above the brine level, and the brine level depressed to that at which it balances the pressure in the steam-room, while the brine is constantly discharged at (B). By this means the brine level is kept constant at (L) ; if the height of the brine outlet (B) is so arranged as to allow for the maxi- mum output of secondary steam through the hole (S), a suitable brine level will always be existing, whilst if the production of secondary steam is reduced the brine level would rise, but the risk of priming is then lessened by the diminished evaporation. A large blow off is provided