Pumping Water by the Air Lift Method

by Orin Kenzie, Alberta Agriculture, Lethbridge, Alberta

Lately, I have had several inquiries about the air lift method of water pumping. The following information may be of help to those planning such an installation. The air lift system has been used for many years, and many well drilling outfits are used to pump and develop water wells. They are easy to install and are not damaged when sand is pumped with the water.

Air lift operates by the injection of compressed air into the water inside of a discharge pipe, at a point below the water level in the well. The injection of the air results in a mixture of air bubbles and water, which being lighter in weight than water outside the discharge pipe, forces the air/water mixture up.

Two critical factors in air lift pumping are:

  1. the submergence of the air line; and
  2. the size of discharge line.

    Submergence always means the depth of air line below the pumping level, rather than the static water level in the well. Best performance occurs when approximately 60% of the airline is submerged. If the percent of submergence is too low, the system will not work.

    he piping assembly used for air lift pumping consists of a vertical discharge pipe and a smaller air pipe. See Figure 1.

    A foot piece that breaks the air into many small bubbles improves the efficiency of the airlift. Afoot piece can be made by drilling a number of small holes (1/16") in a short piece of copper tubing (1/2") and attaching it to the lower end of the air line. The part of the tube with the holes should extend at least two feet into the discharge pipe. The energy that is available to operate the air lift is that contained in the compressed air. Compressed air is then forced down the air pipe and released inside the discharge pipe.

    Table 1 provides the sizes of air lines, and size of discharge pipe used under most farm conditions.

    Table 2 provides for the depth of submergence, below pumping level and the volume of air required.


    TABLE 1
    Pumping Rate (Gal.
    per Minute)
    Size of Plastic Discharge
    Pipe
    Size of Plastic Air
    Line
    1-3
    1/2 inch
    1/2 inch
    3-6
    3/4 inch
    1/2 inch
    6-9
    1 inch
    1/2 inch


    TABLE 2
    AIR LIFT PERFORMANCE FOR MINIMUM AND BEST SUBMERGENCE
    Depth to Pumping Water
    Level
    Depth of Air Line Below
    Pumping Water Level
    Volume of Air Required Per
    Gallon of Water Pumped
    25 feet
    29 feet (minimum)
    53 feet (best)
    0.33 cubic ft./min.
    0.18 cubic ft./min.
    50 feet
    52 feet
    93 feet
    0.60 cubic ft./min.
    0.36 cubic ft./min.
    100 feet
    89 feet
    150 feet
    0.33 cubic ft./min.
    0.18 cubic ft./min.
    150 feet
    113 feet
    183 feet
    1.42 cubic ft./min.
    0.74 cubic ft./min.
    200 feet
    139 feet
    216 feet
    1.75 cubic ft./min.
    1.00 cubic ft./min.
    250 feet
    160 feet
    240 feet
    2.12 cubic ft./min.
    1.24 cubic ft./min.




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