Most of the water exits through the waste gate, but a portion is forced into the accumulator. The pressure which develops in the hydraulic accumulator can raise water over 300 feet. The system relies on air pressure in the surge tank. Here is an exploded view of the Gravi-Chek pump mechanism. The motorless property of this pump combined with its simple construction and short parts list make this pump particularly suitible for remote location use.
Delivery rates go down as lift height goes up and vice-versa.
The chart indicates for example that a 30 foot drive pipe with a 6 foot fall can deliver 4,000 gallons a day to a height of 20 feet, or 3,000 gallons a day to a height of 40 feet. The same pump can also deliver 1000 gallons a day to a height of 150 feet, according to the manufacturer's specifications.