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

78 SEA WATER DISTILLATION. be again referred to when dealing with the subject of “ brine discharge.” When the feeding and brining take place inwards and outwards by a constant flow, auto- matically worked, there would appear to be no need for this valve on the secondary steam pipe, but where the arrangement is for the brine to be blown out rapidly at intervals, then the valve would be necessary to perform this operation. Safety Valve. 22. When an evaporator is designed for working with a pressure inside the casing above that of the atmosphere, it should be provided with a safety valve of sufficient size and load to prevent a greater pressure being possibly obtained than is sufficient to meet all emergencies. The Board of Trade rules make this obligatory, and so do Admiralty requirements. (B) Gas-heated Steam Generators. 23. In the foregoing part of this chapter evaporators worked by steam heat only have been dealt with, and although a little digressive, we may here just refer to that class of evaporators which are worked by the heat of a gas stove or oil lamp, instead of by steam heat. When fire is used as a heating agent the term boiler is generally used, but a boiler is generally a much larger affair than is required for the particular purpose in view—viz., the production of distilled water of exceptional purity in very small quantities, not more in fact than a few gallons per day. Under such circumstances, gas is undoubtedly the most convenient form of supplying this almost miniature type of distilling plant required.