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

202 SEA WATER DISTILLATION. suitable safety valve on the cover, loaded to the maximum pressure attainable in the casing. 3. Pressure Gauge. 68. It is also convenient to have a steam gauge on the first evaporator, showing the pressure inside the coils, and a suitable pressure gauge on the final evaporator steam- room, for indicating the pressure of the final steam before it is discharged. If the final evaporator is working at a pressure below the atmosphere, a vacuum gauge should be fitted. 4. Starting Valve. 69. A starting valve should be fitted for the primary steam, as it enters the first evaporator coils, but as the gained steam, afterwards generated, works directly from evaporator to evaporator, there is no need for any steam valve for the entry of the steam to each of the other evaporators. The steam (i.e., the gained steam) gener- ated outside the coils of each evaporator may be connected direct to the steam inlet to coils of the following evapor- ator, as the gained steam of the first evaporator becomes the primary steam of the second evaporator, and the gained steam of the second evaporator becomes the prim- ary steam of the third evaporator, and so on, till the final evaporator is reached, which works at atmospheric pres- sure, or to as much below it as it is thought expedient to carry the successive distillations. 5. Water Gauge. 6. Blow-off. 70. Each evaporator should also be fitted with a water gauge, to indicate the brine level in the evaporator. The brine of each pressure evaporator may be blown from the