All About Engines

i8o All About Engines hope renewed which have made the turbine what it is will never be written. Air Pumps for Turbines From what has been written it will be clear that to attain its highest efficiency the turbine must be provided with a good condenser and an air pump that will produce a very high vacuum. For this purpose ordinary reciprocating pumps with pistons and valves and relatively large clearance spaces are not com- pletely satisfactory. A rotary air pump, invented by M. Maurice Leblanc, and manufactured by the British Westinghouse Co., is shown in Fig. 108, Plate 16, and shown diagrammatically in use in Fig. 109. It is practically a centrifugal pump combined with an ejector, and an ejector is the same in principle as an injector, but employed to draw fluid out instead of to force it into a vessel. It must be remembered that the purpose of the pump is to draw air out of the condenser, so that in an ordinary piston pump the air makes its own escape by lifting the valves from which the piston has re- moved the pressure. In the Leblanc pump there are no valves. Referring to the plate, the opening c is connected to the condenser, and water—called sealing water on account of the purpose it is to serve —enters the pump along the pipe a. The wheel is rotated at a high speed, and the water, passing through the fixed guide nozzle b, is flung out through the vanes d in thin sheets which fill up the nozzle e and move downwards toward the outlet h. Between