Water Lifted By Compressed Air
For Municipal, Manufacturing, Irrigation or Other Water Supply

THEORY OF THE AIR. LIFT. Opinions differ as to the true theory of the Air Lift. A common Air Lift case is one where we have a driven well in which the water has risen approximately near the surface. We place in this well a large pipe for the discharge of the water. This is known as an 11 educ- tion pipe.” This pipe does not touch the bottom of the well, but is elevated above it so as to freely admit the water through its lower open end. Alongside of this pipe, either on the outside or within, is a small pipe properly proportioned and intended to convey com- pressed air to a point near the bottom of the eduction pipe. It is usual to provide what is called a “foot-piece,” which forms the nozzle connecting the air pipe with the water pipe, but in what is known as the “central pipe system” this foot-piece is not used, the air pipe being placed within the eduction pipe to a point near the bottom, where it discharges the compressed air into the water column. 1 he aii pipe is connected with an air receiver on the surface, which is in 01 near the engine room, in which there is an air compressor. This air pipe is provided with a valve on the surface. Before turning on the air the conditions in the well show water at the same level on the outside and inside of the eduction pipe. At the first operation we must have sufficient air pressure to discharge the column of water which stands in the eduction pipe. This goes out en masse, after which the pump assumes a normal condition, the air pressure being lowered and standing at such a point as corresponds with the normal conditions in the well. This is determined by the volume of water which the well will yield in a certain time and the elevation to which the water is discharged. Here comes in the value of experience in laying out the pipes, which should be proportioned to meet normal conditions. The Frizell System or Lifting by Bubbles. It was at first supposed that in all air lift cases the water was discharged because of the aeration of the water in the eduction pipe, due to the intimate comingling of air and water. Bubbles of air rising m a water column not only have a tendency to carry particles of water with the air, but the column is made lighter, and, with a submergence or weight of water on the outside of the eduction pipe, there would naturally be a constant discharge of air and water. This is known as the Frizell System, and where the lifts are moderate—that is, where the water in the well reaches a point near the surface—it is very likely that the discharge is due to simple aeration. 14