THE PNEUMATIC BLAST GRAIN-LIFTER
differs from the system just described in that the grain is driven through the pipes or hoses by air compressed to several pounds above atmospheric pressure. A small tube attached to the main hose conveys compressed air to the nozzle through which grain enters the tube. The nozzle consists of a short length of metal piping which is buried in the grain. One half of it is encased by a jacket into which the compressed air rushes. As the air escapes at high speed past the inner end of the piping into the main hose, it causes a vacuum in the piping and draws in grain, which is shot up the hose by the pressure behind it. As already remarked, the action of this pneumatic elevator is similar to that of a steam injector.