for week of February 26, 2006:
Airline 1. (noun) A steel or PVC open-ended pipe or tube (typically ½-inch to 2-inches in diameter) used to convey compressed air. On reverse-circulation drilling rigs, an airline extends down through the center of the kelly and uppermost joints of drill pipe. Dual-walled drill pipe may also be used to convey the compressed air. When air is blown through the airline, it creates a venturi effect (area of low pressure), which causes water to circulate up the drill pipe.
2. (noun)An open-ended pipe or tube, typically made of brass, steel, or some other durable material, which is suspended from the well head to near the top of the pump bowls, for the purpose of measuring groundwater levels in response to the hydraulic pressure heads within the airline. The groundwater within the airline is typically evacuated by introducing compressed air or nitrogen into the airline from the land surface. A pressure gauge connected to the airline can then be used to measure the pressure required to displace the water from the airline, enabling a determination of the depth-to-water in the well.