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

THE EVAPORATOR. 97 in the alloy makes it impossible to solid-draw it into tubes. 61. Therefore, taking all matters into consideration, copper would appear to be the best material of all for evaporator coils. There is no need to tin the coils, either inside or out, if the primary water is condensed from the exhaust steam on board, which is greasy, and is returned to the boiler, but if the primary water is used (as in land apparatus) for drinking purposes, the interior of the evaporator coils should be tinned. Evaporative Surfaces—How Fitted. 62. The coil, whether copper or brass, is either brazed or expanded into the end pieces, which are fitted to the casing as already shown. If the tube ends are brazed into these end pieces, the same will have to be made of brazing metal, but if the tube ends are expanded into the end pieces, then the same are made of gun-metal. The latter is by far the best work, as gun-metal is stiffer and better than brazing metal. If the tube ends are expanded in, they should be softened so as to facilitate expansion. 63. The joint made between the end pieces and the casing has already been shown in Figs. 9 and 9a. The joint is made by having a spigot or cone on the tube end or casting which fits into the hole in the pocket, and the joint is then tightened up by means of either one large nut, somewhat like an ordinary union joint (see Fig. 9), or the joint may be tightened up like an ordinary flange with a couple of nuts with studs (Fig. 9a). These studs are best made of phosphor bronze or manganese bronze, these metals being stiffer than gun-metal. It is not,