Automatic liquid dispenser using solar energy e.g. for watering plants comprises container with space above liquid for air expansion and outlet tube

摘要

The automatic dispenser consists of a rigid container ((1) for the liquid, e.g. water, closed by a sealed screw cap (2) with a hole for a capillary tube (3) with a vent (6) at the top. A thin float (7) on the surface of the water prevents evaporation as the dark-coloured outer surface of the container absorbs heat from the sun. As the air in the space (4) above liquid expands, the liquid is forced up the capillary tube and out through its outlet end. The vent lets in air when the container cools at night.