Fig. 544.
A double tube ejector is represented in Fig. [542]. This is calculated to use steam economically by reason of its having two tubes, besides it is well made and properly proportioned to raise water to high elevations.
Fig. [543] is a cheaper form of apparatus and is designed to elevate water to very moderate heights and where a saving of steam is not of so much consequence as in localities where the price of coal is high.
The jet pump presented in Fig. [544] is another compact form of this style of ejector and is adapted for its own particular class of work which is but little known to those unaccustomed to use these appliances.
When working either an injector or ejector from a long lift or with a long pull through horizontal piping, it takes several minutes to exhaust the air from the pipe when steam is turned on, resulting in a considerable waste of steam each time the injector is started. This waste can be done away with by the use of a foot valve.
Fig. 545.
