The top of the pipe that connects the upper reservoir to the air chamber is positioned just below the water surface.

A narrow riser pipe extends from the air chamber up to the higher elevation to which the water will be pumped.

[1] However, Charles H. Taylor invented the hydraulic air compressor before the year 1910 while living in Montreal.

Expelling the water up to 30 meter high serves to prevent potentially damaging over-pressure.

The primary purpose of the pulser pump is to use the air pressure to expel the water to a higher elevation.