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.

74 THE STEAM INJECTOR. supply can be cut off independently of the main supply by the cock c, it being found in practice that a high degree of vaøuum always exists at b, but that a supplementary water supply is only required when the feed water is so hot that the main supply is unable to properly condense the steam within the limits of the combining nozzle. The ratio of water to steam passing through an injector decreases with an increase in the temperature of the feecl water and in the pressure of the entering steam, but the provision of tlie supplementary water inlet ensures an Fig. 54. increase in the quantity of water passing through the appliance over what would be given by one water inlet only. With both the forms of injector shown at figs. 52 and 53 the supplementary water supply has a very important effect. The main supply of water is in contact with the steam from the lifting steam nozzle for a considerably longer period than the supplementary supply. The latter therefore cxerts a strong- cooling action on the steam from the forcing steam nozzle and tends to reduce the tempera-