The Steam Injector
A theoretical and practical treatise on the design and operation of injectors and on the flow of fluids through and the design of nozzles.

52 THE STEAM INJECTOR. the flap is closed, due to the difference of the pressures in the nozzle b and in the overflow chamber c. Iheie is thus during normal working an unbroken passage for the jet travelling through the combining nozzle. Many other proposals have been made for automatically opening and closing an overflow aperture in the combining nozzle of an injector. A few of the more important, which have come into extensive use, are given below. Fig. 27 shows an arrangement comprising a separate compartment a, with a non-return valve b thereon, around tlie overflow gap c. The valve b acts in a similar maimci to the flap in fig. 26. Fig. 28 is an external view of an injector constructed as shown in fig. 27. Fig. 29. One form of the Gresham automatic sliding nozzle injector is shown at figs. 29 and 30. In this arrangement the steam from the passage B, after passing through the steam nozzle 1, enters the lifting cone 2, where it meets the water from the water-inlet pipeD. When the injector is starting, and is unable to deliver into the boiler b&ing fed, the pressure in the space F acts on the sliding combining nozzle 3 to force it towards the delivery nozzle 4, so providing a large overflow gap at E, through which. overflow takes place to the chamber C. When, liowever, the injector oom- mences to work normally, the delivery pressure rises, and, acting in the space G upon the nozzle 3, forces it towards