430

MODERN STEAM PRACTICE.

a separate centrifugal pump is used, driven by a small engine, forcirculating the water, and two air pumps are fitted, the centrifugalpump should be arranged to pump the bilge water overboard, andone of the air pumps turned into a circulating pump, the requisitevalves being placed so as to be opened at the shortest notice. Toprovide against any accident to the surface System, a plain injectionvalve is placed on the condenser, and a valve is also fitted at someconvenient part to drain all the water out of the condenser whennecessary.

Various arrangements of the tubes for surface condensers areadopted. For direct-acting horizontal engines of the return con-necting-rod type, they are ar-ranged vertically, placed betweenthe crosshead guides in one, oreise there is a separate condenserfor each cylinder. The steamfrom the cylinders enters abovethe top plate, and being Con-densed falls directly through thetubes into the air pump, whichis situated on the inside of theouter frame, and worked directlyfrom the steam piston, while thecirculating pump occupies thesame position as regards theother cylinder; the water is

drawn through the vessel containing the tubes, coming in at thetop, circulating around the tubes, and being drawn away, insteadof forced, by the circulating pump. The bottom part of the con-denser is generally cast in two, containing the guide bars for thepiston-rod crosshead, the chamber for the gun-metal air pump orcirculating pump, barrel, valve seats, air vessels, &c. The flangefor holding the bottom tube plate extends the length and breadthof the casting between the guide bars, and is planed all over; thebottom tube plate is fitted on it, the vessel containing the tubes isplaced over it, and the top tube plate secured on the top. Abovethis is placed the top part of the condenser, where the steam enters;it is fitted with covers on the top for getting at the tubes, thebottom joints are reached through a door on the bottom chamber

D

Fig. 313.—Vertical Arrangement of Tubes for ReturnConnecting-rod Engines.

a, Tube chamber.

B, Air pump,pump.

C, Circulating

of sufficient height for a man to enter.

Some arrangements of the